Scientific American Supplement, No. 358, November 11, 1882
by
Various
Part 2 out of 3
engineers, reservoirs, and steam. Carbonic acid gas is both the working
and extinguishing agent.
2d. In promptness. It is always ready. No steam to be raised, no fire to
be kindled, no hose to be laid, and no large company to be mustered. The
chemicals are kept in place, and the gas generated the instant wanted.
In half the cases the time thus saved is a building saved. Five minutes
at the right time are worth five hours a little later.
3d. In efficiency. Mere water inadequately applied feeds the fire, but
carbonic acid gas never. Bulk for bulk, it is forty times as effective
as water, the seventy gallons of the two smallest cylinders being equal
to twenty-eight hundred gallons of water. Besides, it uses the only
agent that will extinguish burning tar, oil, and other combustible
fluids and vapors. One cylinder can be recharged while the other is
working, thus keeping up a continuous stream.
4th. In convenience. Five or six men can draw it and manage it. Its
small dimensions require but small area, either for work or storage. One
hundred feet or more of its light, pliant hose can be carried on a man's
arm up any number of stairs inside a building, or, if fire forbids, up a
ladder outside.
5th. In saving from destruction by water what the fire has spared.
It smothers, but does not deluge; the modicum of water used to give
momentum to the gas is soon evaporated by the heat, doing little or no
damage to what is below. This feature of the engine is of incalculable
worth to housekeepers, merchants, and insurance companies.
6th. Economy. It costs only about half as much as a first class hand
engine, and about one-fourth as much as a steam engine, with their
necessary appendages, and the chemicals for each charge cost less than
two dollars.
* * * * *
HOW TO TOW A BOAT.
A correspondent of _Engineering News_ says: Those living on swift
streams, and using small boats, often have occasion to tow up stream. So
do surveyors, hunters campers, tourists, and others. One man can tow a
boat against a swift current where five could not row.
Where there are two persons, the usual method is for one to waste his
strength holding the boat off shore with a pole, while the other tows.
Where but one person, he finds towing almost impossible, and when bottom
too muddy for poling and current too swift for rowing, he makes sad
progress.
[Illustration]
The above cut shows how one man can easily tow alone. The light
regulating string, B, passes from the stern of the boat to one hand of
the person towing, T. The tow line, A, is attached a little in front of
the center of the boat. Hence when B is slackened the boat approaches
the shore, while a very slight pull on it turns the boat outward. The
person towing glances back "ever and anon" to observe the boat's line of
travel.
* * * * *
RAILWAYS OF EUROPE AND AMERICA.
The following table, which has been prepared by the French Ministry of
Public Works, gives the railway mileage of the various countries of
Europe and the United States up to the end of last year, with the number
of miles constructed in that year, and the population per mile:
Total Built in 1881 Population per Mile
Germany 21,313 331 2,154
Great Britain 18,157 164 1,939
France 17,134 895 2,170
Austria-Hungary 11,880 262 3,200
Italy 5,450 109 5,321
Spain 4,869 176 3,492
Sweden & Norway 4,616 273 1,408
Belgium 2,561 48 2,203
Switzerland 1,557 22 1,831
Holland 1,426 83 2,885
Denmark 1,053 25 1,919
Roumania 916 56 5,860
Turkey 866 - 2,891
Portugal 757 8 5,870
Greece 6 - 28,000
------- ----- ------
Total 107,306 2,455 3,168
United States 104,813 9,358 502
It appears from this that the United States mileage was only 2,493 less
than the total of all Europe, and at the present time it exceeds it, as
the former country has built about 6,000 miles this year, whereas Europe
has not exceeded 1,500. The difference in the number of persons per mile
in the two cases is also very great, Europe taking six times as many
persons to support a mile of railway as the States, and can only be
accounted for by the fact that American railways are constructed much
cheaper than the European ones.
* * * * *
BEFORE IT HAPPENED.
AT 9 A.M. on Wednesday, September 13, the correspondent of a press
agency dispatched a telegram to London with the intimation that the
great battle at Tel-el-Kebir was practically over. It may possibly
astonish not a few of our readers (says a writer in the _Echo_), to
learn that this message reached the metropolis between 7 and 8 o'clock
on the same morning; and, in fact, had an unbroken telegraphic wire
extended from Kassassin to London, Sir Garnet Wolseley's great victory
might have been known here at 6:52 A.M., or (seemingly) at a time when
the fight was raging and our success far from complete. Nay, had the
telegram been flashed straight to Washington in the United States, it
would have reached there something like 1 h. 44 m. after the local
midnight of September 12. Paradoxical as this sounds the explanation
of it is of the most simple possible character. The rate at which
electricity travels has been very variously estimated. Fizeau asserted
that its velocity in copper wire was 111,780 miles a second; Walker
that it only travels 18,400 miles through that medium during the same
interval; while the experiments made in the United States during the
determination of the longitudes of various stations there still further
reduced the rate of motion to some 16,000 miles a second. Whichever of
these values we adopt, however, we may take it for our present purpose,
that the transmission of a message by the electric telegraph is
practically instantaneous. But be it here noted, there is no such a
thing as a _hora mundi_ or common time for the whole world. What is
familiarly known as longitude is really the difference in time, east
or west, from a line passing through the north and south poles of
the earth; and the middle of the great transit circle is the Royal
Observatory at Greenwich. If in the latitude of London (51 deg. 30' N.),
we proceed 10 miles and 1,383 yards either in an easterly or westerly
direction, we find that the local time is respectively either one minute
faster or one minute slower than it was at our initial point. Let us
try to understand the reason of this. If we fix a tube rigidly at any
station on the earth's surface, pointing to that part of the sky in
which any bright star is situated when such star is due south (or, as it
is technically called, "on the meridian"), and note by a good clock the
hour, minute, and second at which it crosses a wire stretched vertically
across the tube, then after a lapse of 23 h. 56 m. 4.09 s., will that
star be again threaded on the wire. If the earth were stationary--or,
rather, if she had no motion but that round her axis--this would be the
length of our day. But, as is well known, she is revolving round the sun
from left to right; and, as a necessary consequence, the sun seems to be
revolving round her from right to left; so that if we suppose the sun
and our star to be both on the wire together to-day, to-morrow the sun
will appear to have traveled to the left of the star in the sky; and the
earth will have that piece more to turn upon her axis before our tube
comes up with him again. This apparent motion of the sun in the sky is
not an equable one. Sometimes it is faster, sometimes slower; sometimes
more slanting, sometimes more horizontal. Thus it comes to pass that
solar days, or the intervals elapsing between one return of the sun to
the meridian and another, are by no means equal. So a mean of their
lengths is taken by adding them up for a year, and dividing by 365;
and the quantity to be divided to or subtracted from the instant of
"apparent noon" (when the sun dial shows 12 o'clock), is set down in the
almanac under the heading of "The Equation of Time." We may, however,
here conceive that it is noon everywhere in the northern hemisphere when
the sun is due south. Now the earth turns on her axis from west to east,
and occupies 24 h. in doing so. As all circles are conceived to be
divided into 360 deg., it is obvious that in one hour 15 deg. must pass beneath
the sun or a star; 30 deg. in two hours, and so on. The longitude of
Kassassin is, roughly speaking, 32 deg. east, so that when the sun is due
south there, or it is noon, the earth must go on turning for two hours
and eight minutes before Greenwich comes under the sun, or it is noon
there, which is only another way of saying that at noon at Kassassin it
is 9 h. 52 m. A.M. at Greenwich. It is this purely local character
of time which gives rise to the seeming paradox of our being able to
receive news of an event before (by our clocks) it has happened at all.
* * * * *
THE ADER RELAY.
This new instrument has excited considerable interest among telegraph
and telephone men by its exceeding sensitiveness. It is so sensitive
to the passage of an electric current that a battery formed with an
ordinary pin for one electrode and a piece of zinc wire for the other,
immersed in a single drop of water, will give sufficient current
to operate the relay. In practice it has successfully worked as a
telephonic call on the Eastern Railroad Company's line between Nancy
and Paris, a distance of 212 miles, requiring but two cups of ordinary
Leclanche battery.
The instrument consists of two permanent horseshoe magnets, fixed
parallel with each other and an inch apart. A very thin spool or bobbin
of insulated wire is suspended, like the pendulum of a clock, between
these permanent magnets, in such a manner that the bobbin hangs just
in front of the four poles. A counterpoise is fixed at the top of the
pendulum bar, which permits the adjusting of the antagonistic forces
represented by the action of the swinging bobbin, and two springs, which
are insulated from the mass, and which form one electrode of the local
or annunciator circuit, while the pendulum bar forms the other.
It will be easily understood that as the bobbin hangs freely in the
center of a very strong magnetic field (formed by the four poles of the
two permanent magnets), the slightest current sent through the bobbin
will cause the bobbin to be attracted from one direction, while it will
be repelled from the other, according to the polarity of the current
transmitted.
As the relay has a very low resistance, it is evident that it will
become an acceptable auxiliary in our central office, particularly when
used as a "calling off" signal, as by its use the ground deviation, so
objectionable and yet so universally used for "calling off" purposes,
can be entirely avoided, and the relay left directly in the circuit, as
is being done here in Paris. R. G. BROWN.
Paris, September 12, 1882.
* * * * *
THE PLATINUM WATER PYROMETER.
By J. C. HOADLEY.
The following description of the apparatus used for the determination
of high temperatures, up nearly to the melting point of platinum, is
offered in answer to several inquiries on the subject:
The object to be attained is a convenient and reasonably accurate
application of the method of mixtures to the determination of
temperatures above the range of mercurial thermometers, say 500 deg. F., up
to any point not above the melting point of the most refractory metal
available for the purpose, platinum.
A first requisite is a cup or vessel of convenient form, capable of
holding a suitable quantity of water, say about two pounds avoirdupois.
Berthelot decidedly prefers a simple can of platinum, very thin, with a
light cover of the same metal, to be fastened on by a bayonet hitch. For
strictly laboratory work this may be the best form; but for the hasty
manipulation and rough usage of practical boiler testing something more
robust, but, if possible, equally sensitive, is required. The vessel I
have used is represented in section in the accompanying cut, Fig. 1.
The inner cell, or true containing vessel, is 4.25 inches in diameter;
and of the same height on the side, with a bottom in the form of a
spherical segment, of 4.25 inches radius. It is formed of sheet brass
0.01 inch thick, nickel-plated and polished outside and inside. The
outer case is 8 inches diameter and 8.5 inches deep, of 16-ounce copper,
nickel-plated and polished inside, but plain outside. There are two
handles on opposite sides, for convenience of rapid manipulation. The
top, of the same copper as the sides and bottom, is depressed conically.
like a hopper, and wired at its outer edge, forming a lip all around for
pouring out of. The central cell is connected with the outer case only
by three rings of hard rubber (vulcanite), each 0.25 inch thick, the
middle ring completely insulating the cell from its continuation upward,
and from the outer case. A narrow flange is turned outward at the upper
edge of the cell, and a similar flange is also turned outward at the
lower edge of the cylindrical continuation of the walls of the cell
upward. Between these two flanges, the middle ring of hard rubber is
interposed, and the two parts, the cell and its upward continuation,
are clamped together by the upper and lower rings of hard rubber, which
embrace the flanges and are held together by screws. The joints between
the flanges and the middle ring of hard rubber, which might otherwise
leak a little, are made tight with asphaltum varnish.
[Illustration: Fig. 1.]
Fig 1 shows two partitions, dividing the space between the cell and the
case into three compartments, and a concave false bottom. The cover is
also seen to be divided into three compartments, by two partitions, and
each compartment of the vessel and of its cover is provided with a small
tube for inserting a thermometer. This construction was adopted in the
first instruments made, for the purpose of observing the rate of heat
transmission through the successive compartments, but these parts are
without importance with respect to the practical use of the instrument,
and may as well be omitted, as they considerably increase the cost,
being nickel-plated and polished on both sides. The top and bottom
plates of the cover are of 0.01 inch brass, nickel-plated and polished
on both sides, both convex outward, the bottom plate but slightly, the
top plate to 4.25 inches radius. A ring of hard rubber connects, yet
separates and insulates these plates, and they are bound together with
the ring into a firm structure by a tube of hard rubber, having a
shoulder and knob at the top, and at the lower end a screw-thread
engaging with a thin nut soldered to the upper side of the bottom plate.
When the cover is in place, its lower plate is even with the top of
the cell; and the contained water, which nearly fills the cell, is
surrounded by polished, nickel-plated, brass plates 0.01 inch thick,
insulated trom other metal by interposed hard rubber. The spaces between
the cell and case (a single space if the partitions are omitted), the
space above the hard rubber rings, and the space or spaces in the cover
are all filled with eider-down, which costs $1.00 per ounce avoirdupois,
but a few ounces are sufficient. Soft, fine shavings, or turnings of
hard rubber, are said to be excellent as a substitute for eider-down.
Heat cannot be confined by any known method. Its transmission can be in
some degree retarded, and in a greater degree, perhaps, regulated. Some
heat will be promptly absorbed by the sides, bottom, and cover of the
cell, and by the agitator; but this does no harm, as its quantity can
be accurately ascertained and allowed for. Some will be gradually
transmitted to the eider-down, filling the spaces, and through this to
the outer casing; but this can be reduced to a minimum by rapid and
skillful manipulation, and its quantity, under normal conditions, can
be ascertained approximately, so as not to introduce large errors. But
varying external influences, such as currents of air, caused by opening
doors, or by persons passing along near the apparatus during
the progress of an experiment, which would introduce disturbing
irregularities, can best be guarded against by such spaces as I have
described, filled with the poorest heat-conductor and the lightest
_solid_ substance attainable. Air, although a poor heat-conductor, and
extremely light, is diathermous, and offers no obstruction to the escape
of radiant heat.
The agitator is an important part of the apparatus. Its object, in
this instrument, is twofold. _First_, it serves to produce a uniform
temperature throughout the body of water in the instrument; and
_secondly_, it answers as a support to the heat-carrier of platinum or
other metal, often intensely hot, which would injure or destroy the
delicate metal of the bottom if allowed to fall on it. For this second
purpose, no spiral revolving agitator, such as that commended by
Berthelot, would suffice. The best form is such as I have shown in Fig.
1. A concave disk of sheet-brass, made to conform to the shape of the
bottom of the cell, with a narrow rim turned up all around, of about
0.02 inch thickness, is liberally perforated with holes to lighten it,
and to give free passage to water. The concave form causes the streams
of water, produced by slightly raising and lowering the agitator, to
take a radial direction downward or upward, so as to cross each other
and promote rapid mixing. By a slight modification small vanes might be
turned outward from the surface of the metal, which would produce mixing
currents if the agitator were given a slight reciprocatory revolving
motion, thus avoiding the alternate withdrawal and re-immersion of any
part of the stem so strongly deprecated by Berthelot; but for several
reasons I think an up and down motion of the agitator desirable in this
instrument. The platinum heat carrier, sometimes at a temperature of
2,500 deg. to 2,800 deg. F., is thereby brought into more rapid and forcible
contact with the water, steam or water in the spherical condition is
washed away from its surface, and by cooling it more rapidly, the
duration of the observation is lessened, and errors due to transmission
of heat through the walls of the instrument are diminished. The upper
part of the agitator stem is of hard rubber, and the brass portion,
which terminates at the under side of the cover when the agitator is in
its lowest position, suspended by the shoulder at the upper end, need
never be lifted for the purpose of mixing out of the hard rubber tube at
the cover, so that loss of heat from this cause must be very slight.
The brass tube is very freely perforated with holes to admit water,
streaming radially through the holes in the agitator, to contact with
the thermometer. The hole in the stem at the top is flared, to receive
a cork, through which the thermometer is to be passed. The bulb of the
thermometer should be elongated, and very slightly smaller in diameter
than the stem. After passing it through the cork, a very slight band--a
mere thread--of elastic rubber should be put around the bulb, near its
lower end, or a thin, narrow shaving of cork may be wound around and
tied on, to keep it from contact with the brass tube, for safety; and a
little tuft of wool, curled hair, or hard rubber shavings should be
put in the bottom of the brass tube to avoid accidents. For the same
purpose, a light, but sufficient fender of brass wire, say 0.03 inch
diameter, might be judiciously placed around the brass tube at a little
distance, to protect it and the thermometer inside of it from shocks
from the platinum ball when hastily thrown in, as it must always be.
I have had delicate and costly thermometers broken for want of such a
fender. Thermometers cannot be too nice for this work. For accurate work
at moderate temperatures, they should be about 14 inches long, having a
"safe" bulb at the upper end, with a range of 20 deg. F.--32 deg. to 52 deg.--in a
length of 10 inches, giving half an inch to a degree F., and carefully
graduated to tenths of a degree, so that they can be read to hundredths,
corresponding to single degrees of the heat-carrier in the normal use of
the instrument.
For the determination of the highest temperatures, up closely to 2,900 deg.
F., it will be convenient to have thermometers of greater range, say 32 deg.
to 82 deg. F., 50 deg. in a length of 12.5 inches, or a quarter of an inch to
a degree F., also graduated to tenths, or at the least, to fifths of a
degree. Such thermometers will be about 17 inches long.
It is very satisfactory to have _two_ instruments and a good outfit of
thermometers and heat-carriers, in order to take duplicate observations
for mutual verification and detection of errors.
HEAT CARRIERS.
For these platinum is greatly to be preferred to any other known
substance. Its rather high cost is the only objection to its use. Its
heat capacity is low, by weight, but its specific gravity is great, and
sufficient capacity can be obtained in moderate bulk, while its high
conductivity tends to shorten the duration of each experiment or
observation. A convenient outfit for each instrument consists of three
balls, hammered to a spherical form, one 1.1385 inches diameter,
weighing 4,200 grains=0.6 pound avoirdupois; one 0.9945 inch diameter,
weighing 2,800 grains=0.4 pound; and one 0.7894 inch diameter, weighing
1,400 grains=0.2 pound.
These can be obtained at 1-2/3 cents per grain, and will cost,
respectively, $70.00, $46.67, and $23.33, and collectively, $140.00.
At the assumed specific heat of Pt=0.0333+, the heat capacity of the
respective balls will be 1/100, 1/150, and 1/300 of 2 pounds of cold
water, and the two smaller balls used together will be equal to the
larger one. Corrections for varying specific heat of platinum may
be conveniently made by the tables given in a previous article.[1]
Corrections for varying specific heat of water are less important, but
may be made by the following table:
_Temperatures, Fahrenheit, and Corresponding Number of British Thermal
Units Contained in Water from Zero Fahrenheit_.
_______________________________________________________________
Deg | B.t.u. || Deg | B.t.u. || Deg | B.t.u. || Deg | B.t.u. |
----+--------++-----+--------++-----+---------++-----+---------+
32 | 32.000 || 57 | 57.007 || 82 | 82.039 || 107 | 107.101 |
33 | 33.000 || 58 | 58.007 || 83 | 83.041 || 108 | 108.104 |
34 | 34.000 || 59 | 59.008 || 84 | 84.043 || 109 | 109.107 |
35 | 35.000 || 60 | 60.009 || 85 | 85.045 || 110 | 110.110 |
36 | 36.000 || 61 | 61.010 || 86 | 86.047 || 111 | 111.113 |
37 | 37.000 || 62 | 62.011 || 87 | 87.049 || 112 | 112.117 |
38 | 38.000 || 63 | 63.012 || 88 | 88.051 || 113 | 113.121 |
39 | 39.001 || 64 | 64.013 || 89 | 89.053 || 114 | 114.125 |
40 | 40.001 || 65 | 65.014 || 90 | 90.055 || 115 | 115.129 |
41 | 41.001 || 66 | 66.015 || 91 | 91.057 || 116 | 116.133 |
42 | 42.001 || 67 | 67.016 || 92 | 92.059 || 117 | 117.137 |
43 | 43.001 || 68 | 68.018 || 93 | 93.061 || 118 | 118.141 |
44 | 44.002 || 69 | 69.019 || 94 | 94.063 || 119 | 119.145 |
45 | 45.002 || 70 | 70.020 || 95 | 95.065 || 120 | 120.149 |
46 | 46.002 || 71 | 71.021 || 96 | 96.068 || 121 | 121.153 |
47 | 47.002 || 72 | 72.023 || 97 | 97.071 || 122 | 122.157 |
48 | 48.003 || 73 | 73.024 || 98 | 98.074 || 123 | 123.161 |
49 | 49.003 || 74 | 74.036 || 99 | 99.077 || 124 | 124.165 |
50 | 50.003 || 75 | 75.027 || 100 | 100.080 || 125 | 125.169 |
51 | 51.004 || 76 | 76.029 || 101 | 101.083 || 126 | 126.173 |
52 | 52.004 || 77 | 77.030 || 102 | 102.086 || 127 | 127.177 |
53 | 53.005 || 78 | 78.032 || 103 | 103.089 || 128 | 128.182 |
54 | 54.005 || 79 | 79.034 || 104 | 104.092 || 129 | 129.187 |
55 | 55.006 || 80 | 80.036 || 105 | 105.095 || 130 | 130.192 |
56 | 56.006 || 81 | 81.037 || 106 | 106.098 || 131 | 131.197 |
----+--------++-----+--------++-----+---------++-----+---------+
[Footnote 1: _Journal_ for August, pp. 97, 98, and errata in _Journal_
for September, p. 172.]
A composite heat-carrier, of iron covered with platinum, answers well
for temperatures up to about 1,500 deg. F. A ball of wrought iron 0.88 inch
diameter will weigh 700 grains, and a capsule of platinum spun over it
0.048 inch thick, making the outside diameter 0.976+ inch, will also
weigh 700 grains. Upon the assumption of 0.0333+ for the specific heat
of Pt and 0.1666+ for that of Fe, the composite ball will have a heat
capacity equal to that of 4,200 grains of Pt, and equal to 0.01 of that
of 2 pounds of cold water. A patch, about 0.35 inch diameter, has to be
put in to close the orifice where the Pt capsule is spun together, and
a slight stain will show itself at the joint around this patch, from
oxidation of the iron, but the latter will be pretty effectually
protected. Difference of expansion, which will not exceed 0.007 inch
in diameter, will not endanger the capsule of Pt. The interruption of
conductivity at the surface contact of the two metals makes the process
of heating and cooling a little slower, but not noticeably so.
Such composite balls can be obtained for $20 each, $50 less than the
cost of an equivalent ball of solid platinum, which is preferable in all
but cost. Iron balls could be used for a few crude determinations. Cast
iron varies too much in composition, and wrought iron oxidizes rapidly.
While the oxide adheres it gains in weight, and when scales fall off it
loses; and the specific heat of the oxide differs from that of
metallic iron. Whatever metal is used, care must be taken to apply the
appropriate tabular correction for PtFe, or Pt and Fe.
MANIPULATION.
Small graphite crucibles with covers, as shown in section, in Fig. 2,
serve to guard against losing the ball, to handle it by when hot, and to
protect it against loss of heat during transmission from the fire to the
pyrometer. To guard against overturning the crucibles, moulded firebrick
should be provided to receive them, two crucibles being put into one
brick, in the same exposure, whenever great accuracy is desired, each
serving as a check on the other, and their mean being likely to be more
nearly correct than either one if they differ. The firebrick cover
is occasionally useful to retard cooling, if, by reason of local
obstructions, some little delay is unavoidable in transferring the
balls from the fire to the water of the pyrometer. With convenient
arrangements, this may be done in three seconds. After observing the
temperature of the water, make ready for the immersion of the heat
carrier by raising the agitator until a space of only about 1.5 of an
inch is left between its rim and the cover. An instant before putting
in the heat carrier--"pouring" it from the crucible--lift the cover and
agitator both together, so that the rim of the latter is level with the
sloping top of the instrument. The agitator then receives the hot ball
without shock, and no harm is done. If the ball goes below the agitator,
it is likely to injure the bottom of the cup. If, on taking the
temperature of the water before the immersion of the heat carrier, any
change is observed, either rising or falling, the direction and rate of
such change, and the exact interval of time between the last recorded
observation and the immersion, should be noted, in order to determine
the exact temperature of the water at the instant of immersion. The
temperature of the water will continue to rise as long as the heat
carrier gives out heat faster than the cell loses it. The rise will grow
gradually slower until it ceases, and the maximum can be very accurately
determined. Examples of the mode of using the tables, and of determining
the true temperature of the heat carrier at the instant of immersion
from the observations with the instrument, are given in the table on
pages 170 and 171 of this Journal for September. A method of using the
tables, by which a closer approximation to the true temperature may be
reached, will be pointed out in a subsequent article.
[Illustration: Fig. 2.]
DETERMINATION OF THE CALORIFIC CAPACITY OF THE METALS OF THE PYROMETER,
in terms of water, i.e., in British thermal units.
First. Weigh the cup, or cell, the lower plate of the cover and the
metallic portion of the agitator, and compute their heat-capacity by the
specific heat of the respective metals. Compute also the heat capacity
of the thermometer; or, if it be long, of so much of it as is found to
share nearly the temperature of the immersed portion. The result will
be a minimum--indeed, in so small a vessel the inevitable loss by
conduction and radiation will amount to more than one-third as much as
the simple heat capacity of the metals.[1] The total must be ascertained
by an application of the method of mixture. Ascertain the temperature of
the interior of the instrument simply; pour in quickly but carefully a
known quantity of water, say about two pounds, of known temperature, say
about 100 deg. F., and ascertain the temperature as soon after pouring as
mixing can be properly performed. But a correction is necessary for
loss of heat in the act of pouring. To ascertain the amount of this
correction prepare a bath of tepid water, and bring all parts of the
instrument--outside, inside, and interior portions, together with the
vessel to pour from--exactly to one common, carefully ascertained
temperature. Now take two pounds of the water and pour it into the
cell in the same manner as before. Exposure of so thin a stream on
two surfaces to the air of the room will produce a certain degree of
refrigeration in the water, which is supposed to be warmer than the air,
say at about 160 deg. F. This effect will be due to conduction, by contact
with the air, to radiation, and to evaporation; and by so much the
refrigeration observed in mixing is to be diminished.
[Footnote 1: In our case the heat-capacity, thermometer included, was
0.0757; total, 0.1053; radiation, etc., 0.0296. Respectively, 71.9 per
cent, and 28.1 per cent. of the total.]
Four experiments, carefully conducted, gave the following results:
Loss of temperature by pouring at 170 deg. F., 0.81 deg., 0.86 deg., 1.00 deg., and
1.07 deg. F.; mean, 0.935 deg. F.
The following are values of the calorific capacity of my pyrometers,
that is, of those parts of each which share directly the temperature
of the inclosed water, including the thermometer to be used with the
instrument, and the heat communicated to the eider-down and otherwise
lost during an observation, expressed in decimals of a British thermal
unit, or in decimals of a pound of cold water:
0.1048, 0.1052, 0.1077, 0.1008, 0.1028, and 0.1104.
Mean 0.1053 = 0 lb. 1 oz. 11 drms.
Add water 1.8947 = 1 " 14 " 4 "
------ - -- --
2.0000 = 2 " 0 " 0 "
This was the value used. The instrument, being put on delicate coin
scales and counterbalanced, weights equal to 1.8947 lb. avoirdupois = 1
lb. 14 oz. 5 drms., were added to the counterbalancing weights, and cold
water was poured in until the scales again balanced.
The pyrometer with its contained water was then just equal in heating
capacity, while the temperature was not above 38 deg. F. to two pounds of
cold water. The two instruments were sensibly alike, but were numbered
No. 1 and No. 2, and at each observation the one used was noted.
The process of preparation and testing appears long and tedious, and
is indeed somewhat so; but the instruments once well made are durable,
convenient in use, and with care reasonably accurate.
Compared with mercurial thermometers between 212 deg. and 600 deg. F., I believe
them to be much more accurate, although less convenient.
For a range of temperatures from 212 deg. to 900 deg. F. they are certainly
more trustworthy than anything save an air thermometer of suitable
construction; and for all temperatures from 800 deg. to 900 deg. F. up nearly
to the melting point of platinum they are without a rival, so far as I
know.
For some situations the ball can best be inserted in the fire or other
situation where an observation is desired, and withdrawn for immersion
by means of long, slender tongs, with jaws resembling bullet moulds.
A word about the melting point of platinum. My balls certainly began to
melt below 2,950 deg. F., but I am by no means sure that they do not contain
any silver, although their specific gravity gives assurance that they
are at least nearly pure.--_Franklin Journal_.
* * * * *
LOCOMOTIVE PAINTING.
[Footnote: A paper read before the Master Car Painters' Association,
Chicago, September, 1883.]
By JOHN S. ATWATER.
The subject of locomotive painting has been pretty well discussed at the
former meetings of the association, and we have heard many excellent
suggestions regarding the use of oils, mineral paints, and leads from
gentlemen of long experience. But as the secretary has invited a display
of my ignorance I will endeavor to explain as clearly as possible
the methods I pursue, which, though not new or original, have been
productive of good results.
If time enough can be had we can prime with oil alone, or in connection
with the leads or minerals, and be sure of durability; but in these
days of "lightning speed," "lightning illuminations," and "lightning
painting," we must look about for something with "chain lightning" in
it, which, unlike the lightning, will remain bright and stick after it
strikes. We all have to paint according to the time and the facilities
we have for doing the work.
The scale on iron or steel is the only serious trouble which the painter
has to contend with. Rust can be removed or utilized with the oil,
making a good paint, but unless time can be given it is better to remove
the rust.
If possible let tanks get thoroughly rusted, then scrape off scale and
rust with files sharpened to a chisel edge, rub down large surfaces with
sandstone, and use No. 3 emery cloth between rivet heads, etc., then
wash off with turpentine. This will give you a good solid surface to
work upon.
For priming I use 100 pounds white lead (in oil), 10 pounds dry red
lead, 13 pounds Prince's metallic, 8 quarts boiled oil, 2 quarts
varnish, 6 quarts turpentine, and grind in the mill, as it mixes it
thoroughly with less waste. I mix about 250 pounds at a time (put into
kegs and draw off as wanted through faucets).
This _o-le-ag-in-ous_ compound can be worked both ways, quickly by
adding japan, slower by adding oil, and reduce to working consistency
with turpentine.
Without the oil or japan it will dry hard on wrought iron in about seven
days, on castings in about four days. When dry putty with white-lead
putty, thinned with varnish and turpentine, and knifed in with a
"broad-gauge" putty knife. Next day sandpaper and apply first coat
rough-stuff, which is, equal parts, in bulk, white lead and "Reno's
umber," mixed "stiff" with equal parts japan and rubbing varnish, and
thin with turpentine. Next morning, second coat rough-stuff, made with
Reno's umber, fine pumice stone, japan, and turpentine. At 1 o'clock
P.M. put on guide coat for the benefit of the small boys, which is
rough-stuff No. 2, darkened with lamp-black and very thin. The addition
of fine pumice to rough-stuff No. 2 encourages the boys in rubbing, and
prevents the blockstone from clogging.
By the time the last end of the tank is painted the first end is ready
for rubbing, though it is better to stand until next day.
After rubbing sandpaper and put on very thin coat of varnish and
turpentine (about equal parts). This soaks into the filling, hardening
it and making a close, smooth, elastic surface, leaving no brush marks
and being more durable than a _quick_-drying lead. This can be rubbed
with fine sandpaper or hair to take off gloss, and colored the next
morning, but it is better to remain 24 hours before coloring.
Upon this surface an "all japan color" would, before night, resemble a
map of the war in Egypt, but by adding varnish and a very little raw oil
to the "japan color," making it of the same nature as the under surface,
will prevent cracking.
If I sandpaper in the morning, I put on first-coat color before noon.
Second ditto afternoon, and varnish with rubbing varnish that night; rub
down, stripe and letter next day, though I consider it better to stripe
and letter on the color, and varnish with "wearing body varnish."
The tank is then ready for mounting. When mounted I paint trucks and
woodwork, two coats lead, color, "color and varnish," and finish the
whole with "wearing body varnish." Time, from 14 to 16 days.
On cabs I use the same priming as on tanks, let stand five days, putty
nail holes and "plaster putty" hard wood, and give two coats lead, mixed
as follows: 100 pounds keg lead, 19 pounds Reno's umber, 31/2 quarts
japan, 11/2 quarts varnish, 6 quarts turpentine. I call this "No. 2 lead,"
and allow 24 hours between coats, then apply a coat of No. 2 "rough
stuff" at 7 A.M. Rub down at 10 A.M. two coats color, and varnish before
6 P.M. Striped and lettered next day and finished on the following day
if it is not taken away from me, and put on the engine. Time, eleven
days. Can be done in five days.
On castings, same priming, putty and "No. 2 lead" if time is allowed. I
use rough-stuff No. 2 on all flat places, rub down and give two coats
of No. 2 lead. Also painting inside of all castings, and sheet iron
casings; and inside of boiler jacket, with "Prince's metallic."
All castings I get ready for color before they are put on the
locomotive, except such as have to be filed or fitted on outside edges.
As there is very little time given to finish a locomotive after the
machinists get through, I usually finish it _the day before it is done_.
As a sample (one of many), an 8--17--C. locomotive boiler tested
Saturday afternoon, August 12, boiler painted, with 120 pounds steam
on, wheels put under, boiler covered, cab put on, and finished Monday,
August 14, at midnight (did not work Sunday); primed, puttied, colored,
lettered, and varnished same day. After 10 o'clock at night the painters
have a chance, and it is their glorious privilege to work until morning.
The machinists have all the time there is, the painters have what is
left.
So much for the ordinary way. For a quicker method of painting tanks I
send a sample marked No. 1. Time, including first coat varnish, five
days. Priming, 1 pound Reno's umber to 2 quarts pellucedite; two coats
rough-stuff, composed of umber and pellucedite, rubbed down, and thin
coat of pellucedite; one coat drop black, one coat rubbing varnish;
exposed to weather (southeasterly exposure near salt water) March 12,
1879; revarnished one coat, finishing September 1, 1879; remained out
until March 22, 1880. Total exposure, one year and one and a half weeks;
thrown around the shop until August, 1882; has been painted three years
and six months. This is not a sample of good work, but of quick and
rough painting. Considering the time and usuage it has experienced it
has stood much better than I expected, though I cannot safely recommend
that kind of painting when any other can be followed.
Sample No. 3--Time, including two coats varnish, 14 days. Painted as
described in first part of this article; exposed in same places as No.
1, April 3, 1880; total exposure, six months; has been painted two years
and five months.
The above are not exactly "Thoughts on Locomotive Painting." What my
thoughts are would require several dictionaries to express; but that is
owing, not to the kind of work, but having to produce certain results in
a time that will not insure good, durable work.
For removing old paint on wood I use a burner. From iron, I have found
the quickest and most effectual way is to dissolve as much sal soda in
warm water as the water will take up, and mix with fresh lime, making
a thick mortar; spread this on the tank, about an inch thick, with a
trowel; when it begins to crack, which will be in a few minutes, it has
softened the paint enough, so that with a wide putty knife you can take
it all off; then wash off tank with water. This takes off paint, rust,
and everything, including the skin from your hands, if you are not
careful. Plaster one side of tank, and use mortar over again for the
other side.
Engine oil used to brighten smoke stacks, no matter with what painted,
will cause blistering. Tallow and "japan drop black" mixed, and apply
while stack is hot, with an occasional rubbing over with the same, will
remain bright a long time.
Rust always contains dampness, and will feed on itself, extending
underneath and destroying solidly painted surfaces. It is, therefore,
necessary, in order to secure good results, that the rust should be
killed before priming, or that the priming be so mixed that it will
assimilate with the rust and prevent spreading.
Steel tanks will not rust as rapidly as iron, but the scale is more apt
to flake off by the expansion and contraction of the metal, taking the
paint with it.
Heated oil, or heated oil priming, will dry faster and be more
penetrating than cold. I consider heated "boiled oil" and red lead the
best primer for iron.
In regard to ornamentation, my _taste_ is governed by the fact that I
work "by contract," and get no more for a highly ornate locomotive than
I do for a plain one, therefore I like the _plain ones best_, and I
hope that our "good brother Burch's" prophecy, that "the days of 'fancy
locomotives' will return," will never be fulfilled until after I go out
of the business. There is a happy medium between a hearse and a
circus wagon, and the locomotive painter, when not tied down by
"specifications," can produce a neat and handsomely painted engine
without the "spread eagle" or "star spangled banner." My own ideas are
in the direction of simple lines of striping, following the lines of the
surfaces upon which they are drawn.
Finally, take all the time you can get, the more the better, and use
_oil_ accordingly.
* * * * *
"CRACKLE" GLASS.
An ingenious process of producing glass with an iced or crackled
surface, suitable for many decorative purposes, has been invented in
France by Bay. The product appears in the form of sheets or panes, one
side of which is smooth or glossy, like common window glass, while the
other is rough and filled with innumerable crevices, giving it the
frozen or crackled appearance so much admired for many decorative
purposes. This peculiar cracked surface is obtained by covering
the surface of the sheet on the table with a thick coating of some
coarse-grained flux mixed to form a paste, or with a coating of some
more easily fusible glass, and then subjecting it to the action of a
strong fire, either open or in a muffle. As soon as the coating is
fused, and the table is red-hot, it is withdrawn and rapidly cooled. The
superficial layer of flux separates itself in this operation from
the underlying glass surface, and leaves behind the evidence of its
attachment to the same in the form of numberless irregularities, scales,
irregular crystal forms, etc., giving the glass surface the peculiar
appearance to which the above name has been given. The rapid cooling of
the glass may be facilitated with the aid of a stream of cold air, or
by continuously projecting a spray of cold water upon it. By protecting
certain portions of the glass surface from contact with the flux, with
the use of a template of any ornamental or other desired form, these
portions will retain their ordinary appearance, and will show the form
of the design very strongly outlined beside the crackled surface. In
this manner, letters, arabesque, and other patterns in white or colored
glass can be produced with great ease and with fine effect.
* * * * *
HOW MARBLES ARE MADE.
Marbles are named from the Latin word "_marmor_," by which similar
playthings were known to the boys of Rome, 2,000 years ago. Some marbles
are made of potter's clay and baked in an oven just as earthenware is
baked, but most of them are made of a hard kind of a stone found in
Saxony, Germany. Marbles are manufactured there in great numbers and
sent to all parts of the world, even to China, for the use of the
Chinese children.
The stone is broken up with a hammer into pieces, which are then ground
round in a mill. The mill has a fixed slab of stone, with its surface
full of little grooves or furrows. Above this a flat block of oak wood
of the same size as the stone is made to turn round rapidly, and, while
turning, little streams of water run in the grooves and keep the mill
from getting too hot. About 100 pieces of the square pieces of stone
are put in the grooves at once, and in a few minutes are made round and
polished by the wooden block.
China and white marbles are also used to make the round rollers which
have delighted the hearts of the boys of all nations for hundred of
years. Marbles thus made are known to the boys as "chinas," or "alleys."
Real china ones are made of porcelain clay, and baked like chinaware or
other pottery. Some of them have a pearly glaze, and some are painted in
various colors, which will not rub off, because they are baked in, just
as the pictures are on the plates and other tableware.
Glass marbles are known as "agates." They are made of both clear and
colored glass. The former are made by taking up a little melted glass on
the end of an iron rod and making it round by dropping it into a round
mould, which shapes it, or by whirling it around the head until the
glass is made into a little ball.
Sometimes the figure of a dog or squirrel or a kitten or some other
object is put on the end of the rod, and when it is dipped into the
melted glass the glass runs all around it, and when the marble is done
the animal can be seen shut up in it. Colored glass marbles are made
by holding a bunch of glass rods in the fire until they melt; then the
workmen twist them round into a ball or press them into a mould, so that
when done the marble is marked with bands or ribbons of color. Real
agates, which are the nicest of all marbles, are made in Germany, out
of the stone called agate. The workmen chip the pieces of agate
nearly round with hammers and then grind them round and smooth on
grindstones.--_Philadelphia Times_.
* * * * *
DRAWING-ROOM PHOTOGRAPHY.
Among the examples we have received are some which would certainly do
credit to any professional artist, alike for the posing, lighting, and
general treatment; indeed, we may say that some of the poses are of a
high artistic order, and quite a relief from the conventional positions
and accessories so frequently seen in professional work. The expressions
secured are also, as a rule, unusually pleasing and natural. This is, no
doubt, in a great measure due to the sitter feeling more at ease in the
amateur friend's drawing room than in a stranger's studio. Particularly
is this the case in some excellent work--full-length pictures--sent
from the other side of the Atlantic, and taken in a room of very modest
dimensions, and with only one window. Among the failures (if such they
may be called) the chief fault lies in the lighting, and from either
under or over exposure--the former chiefly arising when a landscape lens
was used, and the latter when a portrait combination was employed. Some
correspondents also complain of the long exposure that, in their case,
had been imperative; but, curiously enough, with all the successful
pictures a very brief exposure has always been mentioned, and generally
with an exceedingly small window.
With a view to the further assistance of those who have met with
difficulties, we recur again to the subject of the lighting, for
upon this must entirely depend the success or failure in producing
satisfactory results; and, as we explained in previous articles, unless
proper _chiaroscuro_ is secured on the model, it will be impossible to
obtain it in the picture. The chief defect in this respect has been
either that the light has been too abrupt, and consequently the high
lights are very white and the shadows heavy, giving the pictures an
under-exposed appearance, or the face is devoid of shadow, one side
being as light as the other; hence it lacks the roundness necessary
to constitute a good picture. In most instances the former defect has
arisen from the reflecting screen not being properly placed so as to
reflect back the light in the right direction, or it has been too far
from the model; hence it has lost the greater part of its value. It
should be borne in mind that the nearer the sitter is to the source of
light the nearer the reflector must be to him, and also that at whatever
angle the light falls upon the reflector it is always thrown off at a
corresponding one.
Now, supposing that the light falls upon the model at an angle of, say,
40 deg.: we shall have to place our reflecting screen at somewhat the same
angle, and the nearer it is approached the greater will be the effect
produced. If the sitter be placed very close to the window and the
reflector a long way off, or if it project the light in a wrong
direction, it is manifest that in the resulting pictures the
shadows will, of necessity, be heavy, and the negative will have an
under-exposed appearance, however long may have been given, simply
because there was no harmony in the lighting of the model. In the case
where the picture has been flat it has arisen from the sitter being
placed too far back from the window, so that the direct light falling
upon him has been too feeble to produce any strong lights, and the
reflector arranged so that it received a stronger illumination than
the model, then reflecting it on to the latter, quite overpowering the
dominant lights. The remedy for this is simply to bring the sitter more
forward, so as to obtain a stronger dominant light.
With regard to the time of exposure: we must again impress upon the
student the necessity for placing the sitter as close to the window
as can be conveniently done, for then he will receive the strongest
illumination; and, no matter how strong the shadows which may be
produced, they can always be modified sufficiently by the judicious use
of the reflector. Of course, in practice there is a limit as to the
closeness the sitter can be placed, inasmuch as if too near there will
not be room enough for the background. As we have before said, the
effective light falling upon the sitter is governed by the amount of
direct skylight to which he is exposed. For experiment, let any one seat
himself, say, one foot from the window and sideways to it, and note the
amount of sky that can be seen from this position, then take a seat six
feet within the room, and note it from thence. The difference will be
very marked indeed, and it will fully account for the long exposure that
some have found imperative.
In our previous articles we directed special attention to the advantage
accruing from arranging the sitter in such a position that he received
as much direct light as possible, so that it practically helps to soften
the shadows; hence the sitter should be placed so that he is turned as
little away from the source of light as will enable the desired view of
the face being obtained. That this may the more advantageously be done
the camera should always be placed as close as possible to the side
wall in which the window is situated. As an experiment illustrating the
advantage of this: let a camera be placed close to the wall, then the
sitter arranged so that from that point of view a three-quarter face is
obtained, and it will be noticed that there is very little need of the
reflector at all. Let a negative now be taken, and the camera brought,
say, five feet into the room, and the sitter, without changing his seat,
turned round until a similar view of the face is obtained from that
point. It will now be seen that the shadows are very much deeper than
before, and the reflector will have to be brought pretty close in order
to overcome them; nevertheless they may be obtained quite as soft and
harmonious as in the former case. Let a second negative now be taken,
giving the same exposure as before, and it will be found that if
the first one were correctly timed the second will be considerably
under-exposed. Yet the sitter was at the same distance from the window
in each case.
This shows the advisability of utilizing all the direct light it
is possible to do, and thereby leaving as little as we can to be
accomplished by the reflector. When the sitter is arranged to the best
advantage at a window of ordinary size, fully exposed pictures can
generally be obtained with a portrait lens (full opening) in fairly good
light, on moderately sensitive plates, with one or two seconds' (or even
less) exposure. If a longer exposure than this be necessary, it
may fairly be assumed that the lighting has not been properly
managed.--_British Journal of Photography_.
* * * * *
A NEW METHOD OF PREPARING PHOTOGRAPHIC GELATINE EMULSION BY
PRECIPITATION OF THE BROMIDE OF SILVER.
By FRANZ STOLZE, Ph.D.
I consider the method of precipitation described below as far superior
to any other hitherto employed, particularly on account of its
infallible certainty. I began at first with a thirtieth of the whole
quantity of gelatine, and increased that quantity to a tenth without the
precipitate forming with greater difficulty. The salts were dissolved in
the usual quantity of water, the bromide of potassium was added to the
separately-dissolved gelatine, and both solutions cooled in iced water.
I soon found that even this was not necessary. I accelerated the
solution of the salts by vigorous agitation, so that the temperature
became so much lowered that, even after the addition of the warm
gelatine, it still remained low enough to give the precipitate when
mixed. The mixing took place gradually, all the usual precautionary
measures being observed; such as pouring the silver solution into No.
2 in small quantities at a time, and constantly stirring, and the
separation from the mother lye was complete.
The formula according to which I worked latterly was as follows:
SOLUTION I.
Nitrate of silver...................... 463 grains.
Water................................... 163/4 ounces.
SOLUTION II.
Bromide of potassium................... 355 grains.
Iodide of potassium..................... 15 grains.
Gelatine................................ 46 grains.
Water................................... 163/4 ounces.
After the mixing is completed the perfect separation of the precipitate
takes place in four minutes at most. The clear fluid may be decanted off
almost to the last drop, after which the precipitate is washed three
times with water. In order to dissolve the precipitate pour over it a
solution of 1.5 part of bromide of potassium in 100 parts of water,
agitate, and then add a solution formed of 8 parts of ammonia of the
usual strength in 600 parts of water. The emulsification will begin
at once without any further heating. When now heated on the water
bath--already at from 95 deg. F to 104 deg. F--the whole precipitate will be
suspended, and thin films of the emulsion, when looked through, will
have a grayish tint, but when dry they will appear partially red.
Digestion at 104 deg. F is continued--from half an hour to an hour is
usually long enough--until the film, even when dry, remains violet
through and through. The remaining gelatine, 450 grains dissolved in 16
ounces of warm water, is then added, filtered, and plates coated with
the resultant emulsion. But if it be desired to prepare emulsion for
storage, wash the precipitate finally with alcohol, and store it either
under alcohol or dry it as usual. To use it dissolve in the manner
described above and mix with gelatine.
The great advantages of this process are evident. Not only is the
troublesome washing saved, but, what is more important, the great mass
of the gelatine is added to the emulsion in a condition which secures
to the film a hitherto unattainable firmness. Also, it enables one to
prepare a keeping emulsion with a minimum of alcohol, and, since the
quantity of gelatine in the original emulsion is so small, it dries,
when it is not desired to keep it under alcohol, so much more rapidly,
and thereby also furnishes a more constant preparation.
I am convinced that this process is as yet but in its infancy, and that
it is susceptible of great improvement. From the purely theoretical
standpoint, the property possessed by gelatine, of combining in
sufficiently cold solutions with bromide of silver in the nascent
state, and falling to the bottom in a flaky condition, is exceedingly
interesting. Evidently this property plays a part in the preparation of
emulsion which has not until now been recognized. I do not doubt that
it may be possible to effect, by a sufficiently low temperature,
precipitation even from solutions rich in gelatine, if experiments
in that direction were set on foot. What influence variations in
temperature may have upon the subsequent sensitiveness of the emulsion,
and whether the action of the ammonia and the bromide of potassium is
more energetic, in the absence of the elsewhere-present nitric salts,
are questions which can only be answered after thorough examination;
and the parts played by the various additions of iodide or chloride
of silver in this method of emulsification must likewise also be
ascertained by experiment. The object of this article is to point out
this rich province for research, and to induce experimenters to turn
their attention to it; for it is only after the behavior of emulsion
under all these conditions has been thoroughly examined that we can hope
to reap the best results from the new process.--_Wochenblatt_.
* * * * *
TAYLOR'S FREEZING MICROTOME.
This microtome presents all the advantages of any plan heretofore
employed in hardening animal or vegetable tissues for section cutting,
while it has many advantages over all other devices employed for the
same purpose.
Microscopists who are interested in the study of histology and pathology
have long felt the necessity for a better method of freezing animal and
vegetable tissue than has been heretofore at their command.
In hardening tissues by chemical agents, the tissues are more or less
distorted by the solutions used, and the process is very slow. Ether and
rhigolene have been employed with some degree of success, but both are
expensive, and they cannot be used in the presence of artificial light,
because of danger of explosion. Another disadvantage is that two persons
are required to attend to the manipulations, one to force the vapor into
the freezing box, while the other uses the section-cutting knife.
The moment the pumping of the ether or rhigolene ceases, the tissue
operated on ceases to be frozen, so ephemeral is the degree of the cold
obtained by these means.
The principal advantages to be obtained by the use of this microtome
are, first, great economy in the method of freezing, and, second,
celerity and certainty of freezing. With an expenditure of twenty-five
cents, the tissues to be operated on can be kept frozen for several
hours at a time.
[Illustration: FREEZING MICROTOME.]
Small objects immersed in gum solutions are frozen and in condition for
cutting in less than one minute.
The method of using this microtome can be understood by reference to the
illustration. A represents a revolving plane, by which the thickness of
the section is regulated, in the center of which an insulated chamber is
secured for freezing the tissue. It resembles a pill-box constructed of
metal. A brass tube enters it on each side. The larger one is the supply
tube, and communicates with the pail, a, situated on bracket, s, by
means of the upper tube, t. To the smaller brass tube is attached the
rubber tube, t b, which discharges the cold salt water into a pail
placed under it. (See b.) The salt and water as it passes from pail, a,
to pail, b, is at a temperature of about zero. The water should not be
allowed to waste. It should be returned to the first pail for continual
use, or as long as it has freezing properties. As a matter of further
economy, it is necessary to limit the rate of exit of the freezing
water. This is regulated by nipping the discharge-tube with the spring
clothes pin supplied for the purpose. Should the cold within the chamber
be too intense, the edge of the knife is liable to be turned and the
cutting will be imperfect. When this occurs the flow of water through
the chamber is stopped by using the spring clothes-pin as a clip on the
upper tube. In order to regulate the thickness of the tissue to be cut
a scale is engraved on the edge of the revolving plate, A, which,
in conjunction with the pointer, e, indicates the thickness of the
section.--_Microscopical Journal_.
* * * * *
THE ST. GOTHARD TUNNEL.--It appears that the traffic through the
St. Gothard Tunnel has increased, since the inauguration of through
international services, to such an extent that the Company have already
obtained sanction for laying the second pair of rails in the tunnel. The
Great Eastern Railway Company has increased its steamer traffic, and
built additional station accommodation at Harwich.
* * * * *
VINCENT'S CHLORIDE OF METHYL ICE MACHINE.
Chloride of methyl was discovered in 1840 by Messrs. Dumas and Peligot,
who obtained it by treating methylic alcohol with a mixture of sea salt
and sulphuric acid. It is a gaseous product at ordinary temperature, but
when compressed and cooled, easily liquefies and produces a colorless,
neutral liquid which enters into ebullition at 237.7 deg. above zero and
under a pressure of 0.76 m.
[Illustration: VINCENTS ICE MACHINE. FIG. 1.--THE FREEZER (Longitudinal
Section).]
Up to recent times, chloride of methyl in a free state had received
scarcely any industrial application, by reason of the difficulty of
preparing it in a state of purity at a low price. Mr. C. Vincent,
however, has made known a process which permits of this product being
obtained abundantly and cheaply. It consists in submitting to the action
of heat the hydrochlorate of trimethylamine, which is obtained as a
by-product in the manufacture of potash of beets. The hydrochlorate
is thus decomposed into free trimethylamine, ammonia, and chloride
of methyl. A washing with hydrochloric acid takes away all traces of
alkali, and the gas, which is gathered under a receiver full of water,
may afterward be dried by means of sulphuric acid, and be liquefied by
pressure.
[Illustration: VINCENTS ICE MACHINE. FIG. 2.--THE FREEZER (Transverse
Section).]
Pure liquid chloride of methyl is now an abundant product. There are two
uses to which it is applied: first, for producing cold, and second, for
manufacturing coal tar colors.
[Illustration: VINCENTS ICE MACHINE. FIG. 3.--HALF PLAN OF FREEZER]
At present we shall occupy ourselves with the first of such
applications--the production of cold.
The apparatus serving for the production of cold by this material are
three in number: (1) the _freezer_ (Figs. 1, 2, and 3), in which is
produced the lowering of temperature that converts into ice the water
placed in carafes or any other receptacles; (2) the _pump_ (Figs. 4, 5,
and 6), which sucks the chloride of methyl in a gaseous state up into
the freezer and forces it into the liquefier; and (3) the _liquefier_,
which is nothing else than a spiral condenser in which the chloride of
methyl condenses, and from thence returns to the freezer to serve anew
for the production of cold.
[Illustration: VINCENTS ICE MACHINE. FIG. 4.--THE PUMP (Longitudinal
Section).]
_The Freezer_.--This consists of a rectangular iron tank, 1 meter x 1
meter x 1.5 meters, containing a galvanized plate iron cylinder, A, kept
in place by iron supports. This cylinder contains 24 horizontal tubes,
which are open at the ends and riveted to vertical plates like those of
tubular steam boilers. The tank is filled with a mixture of water and
chloride of calcium, forming, as well known, an incongealable liquid.
Into this liquid are plunged the receptacles containing the water to be
converted into ice. The chloride of methyl is introduced through the
cock, B, into the body of the cylinder, A, and surrounds and cools the
tubes, as well as the incongealable liquid uninterruptedly circulating
in the latter, by means of a helix, C, set in motion by a belt from the
shop. This liquid is thus greatly lowered in temperature and freezes the
water in the receptacles.
[Illustration: VINCENTS ICE MACHINE. FIG. 5.--VERTICAL SECTION OF THE
PUMP.]
_The Pump_.--The pump in the larger apparatus has two chambers of
unequal diameter, that is to say, it operates after the manner of
compound engines.
The machine under consideration, being one that produces a moderate
quantity of ice, has but a single chamber, as shown in Figs 4, 5, and 6.
It is a suction and force pump, whose piston, E, is solid and formed of
two parts, which are set into each other, and the flanges of which hold
a series of bronze segments.
[Illustration: VINCENTS ICE MACHINE. FIG. 6.--PLAN OF THE PUMP.]
The chamber, properly so-called, is of iron, cast in one piece, and is
surmounted with a rectangular tank, F, in which constantly circulates
the cold water designed for cooling the sides of the cylinder; these
latter always tending to become heated through the compression of the
methyl chloride.
The cylinder heads are hollowed out in the middle, and carry the seats
of the suction valves. Each of the latter communicates with a chamber, G
G, in which debouches the pipe, H, communicating with the cylinder, A,
of the freezer (Figs. 1, 2, and 3).
[Illustration: VINCENTS ICE MACHINE. FIG. 7.--THE LIQUEFIER.]
Above the cylinder there are two delivery valves which give access to
the chamber, D, communicating with the worm of the liquefier (Fig. 7)
through the pipe, J.
The piston of the pump is set in motion by a pulley, K, and a cranked
shaft actuated by a belt from the shafting. The piston head is guided by
a slide keyed to the frame.
[Illustration: VINCENTS ICE MACHINE. FIG. 8.--SECTION OF FLANGE OF THE
WORM.]
_The Liquefier_.--This apparatus consists of a cylindrical tank, L, of
3 mm. thick boiler plate, mounted vertically on a masonry base and
designed to be constantly fed with cool water. It contains a second
cylindrical tank, M, of 6 mm. thick galvanized iron. This latter tank is
provided with a cast-iron cover, on which are mounted the worm, N, and a
pipe, O, connected with the tube of the pressure gauge. To the base of
the tank, M, there is affixed, on a cast iron thimble, a cock, P, for
setting up a communication between the tank and the pipe, R, which
returns to the freezer through the cock, B (Fig. 1).
[Illustration: VINCENTS ICE MACHINE. FIG. 9.--VIEW OF THE UNDERSIDE OF
THE SAME.]
The cold water requisite for condensation enters the tank, L, through
a pipe terminating in a pump or a reservoir. The waste water flows off
through the tubulure, Q. The tank is emptied, when necessary, through
the blow-off cock, S.
[Illustration: VINCENTS ICE MACHINE. FIG. 10.--PLAN OF THE WORM.]
_Operation of the Apparatus_.--As has been remarked above, the cylinder,
A, is filled with chloride of methyl. The pump, through suction,
produces in this cylinder a depression from which there results the
evaporation of a portion of the chloride of methyl, and consequently
a depression of temperature which is transmitted to the incongealable
liquid circulating in the tubes, and to the receptacles (carafes or
otherwise) containing the water to be converted into ice.
The pump sucks in the vapor of mythyl chloride through the pipe, H, and
through its suction valves, and forces it into the chamber, D, through
its delivery valves, and from thence into the worm, N, through the pipe,
J. Under the influence of compression and of the water contained in the
tank, L, the methyl chloride liquefies and falls into the receptacle, M,
from whence it returns to the freezer through the pipe, R.
Two pressure-gauges, one of them fixed on the freezer and the other on
the liquefier, permit of regulating the running of the machine. The
vacuum in the freezer is 0 to 1/2 atmosphere, and the pressure in the
liquefier is 3 to 4 atmospheres. These apparatus make opaque ice, but
will likewise produce transparent, if a pump for injecting air is
adjoined. This, however, doubles the time that it takes to effect the
freezing, and carries with it the necessity of doubling the number of
moulds to have the same quantity of ice.
The cost price of ice made by this system depends evidently on the price
of coal in each country, on the perfection of the boiler and motor, as
well as on the power of the freezing machine. Putting the coal at 20
francs per ton, and the consumption at 2 kilogrammes per horse and
per hour, ice may be obtained at a cost of about half a centime per
kilogramme. The apparatus shown in the accompanying figures have been
constructed according to the following data:
Production of ice per hour............ 25 kilogrammes.
Production of heat units per hour..... 2.5 grammes.
Quantity of ice produced per
kilogramme of coal burned........... 5 kilogrammes.
Water of condensation per hour........ 0.75 cubic meter.
These machines are employed not only for the manufacture of ice, but
also in breweries for cooling the air of the cellars and fermenting
rooms, or that of the vats themselves; in manufactories of chemical
products; in distilleries; in manufactories of aerated waters, etc.
They may also be used in the carrying of meats and other food products
across the ocean, and, in a word, in all industries in which it is
necessary to obtain artificial cold.
The power necessary to operate apparatus that produce 25 kilogrammes per
hour is about that of 3 horses.--_Annales Industrielles_.
* * * * *
CARBONIC ACID IN THE AIR.
[Footnote: An address before the Paris Academy.]
By M. DUMAS.
Of all the gases that the atmosphere contains, there is one which offers
a special interest, as well on account of the part ascribed to it in
the mutual interchange going on between the two organic kingdoms, as
on account of the relation that it has been observed to occupy between
earth, air, and water; this gas is carbonic acid.
Ever since the fact has been established that animals consume oxygen
and give out carbonic acid as the product of respiration, while plants
consume carbonic acid and give out oxygen, the question has often been
asked whether the quantity of carbonic acid contained in the air did not
represent a sort of sustaining reservoir which was being continually
drawn on by the plants and resupplied by animals, so that it has
doubtless remained unchanged owing to this double action.
On the other hand, Boussingault has long since shown that volcanic
regions give out through crevices and fumaroles enormous quantities of
carbonic acid. The deposition of carbonate of lime that is continually
taking place on the sea-bottom is, on the other hand, fixing carbonic
acid in quantities which we may accurately estimate from the strata of
limestone seen on the surface of the earth. We might imagine, that in
comparison with the huge volumes of carbonic acid sent forth in volcanic
districts, even in the oldest one, and the mass of carbonate of lime
deposited on the sea bottom, the results attributed to the life of
plants and animals would be of no consequence either for increasing or
diminishing the physiological carbonic acid in the air comparable with
those which are accomplished by the purely geological exchange.
Schloesing has recently succeeded, by a happy application of the
principle of dissociation, in showing that the amount of carbonic acid
in the air bears a direct relation to the quantity of bicarbonate
of lime dissolved in sea water. If the quantity of carbonic acid
diminishes, the bicarbonate of the water is decomposed, half of its
carbonic acid escapes into the atmosphere, and the neutral carbonate of
lime is precipitated. The aqueous vapor condensed from the air dissolves
part of the carbonic acid contained therein, and carries it along, when
it falls as rain upon the earth, and takes up there enough lime to form
the bicarbonate, which is thus carried back to the sea.
The physiological role of carbonic acid, its geognostic influence, and
its relations to most ordinary meteorological phenomena on the earth's
surface--all these contribute to give special weight to studies
concerned in the estimation of the normal quantity of carbonic acid in
the air.
Nevertheless, this estimation is attended with great difficulty. Not
everyone is able to take up such questions, and not all processes are
adapted to it. The first thought which would naturally arise would be to
inclose a known volume of air in a given vessel, and then determine its
carbonic acid by measuring or weighing it. In this way we should obtain
the exact relation between a volume of air and the volume of carbonic
acid in it, for any given moment, and in any given place. If, however,
this be done with a ten-liter flask, for example, it would only hold
3 c.c. of carbonic acid, weighing 6 milligrammes; and, whether it is
weighed or measured, the error may easily equal 10 per cent. of the real
value, hence no deductions could be drawn from the observed facts.
For this reason larger volumes of air were taken, and a current of air,
whose volume could be accurately measured by known methods, was passed
through condensers capable of retaining the carbonic acid. But in this
case the air must pass very slowly through it, so that the process may
last several hours; and since the air is continually in motion, owing to
vertical and horizontal currents, the experiment may be begun with the
air of one place, and concluded with air from a far distant spot. For
example, if an experiment lasting twenty-four hours was made in Paris
when the air moved but four meters per second (nine or ten miles per
hour), it might be begun with air from the Department of the Seine, and
end with air from the Department of the Rhone, or the Belgian frontier,
according to the direction of the wind.
So long as we had no analytical methods of sufficient delicacy to
estimate with certainty the hundredth, or at least the tenth of a
milligramme of carbonic acid, it was very difficult to determine the
quantity in the air at a given time and place. It is frequently possible
to analyze upon the plain air that has descended from the heights
above, and to examine by bright daylight the effect of night upon the
atmosphere.
Still other difficulties show themselves in such investigations. It
seems very easy to collect carbonic acid in potash tubes, and to
determine its amount from the increase in weight of the tubes; but,
alas! to how many sources of error is this method exposed. If the potash
has been in contact with any organic substance, it will absorb oxygen.
If the pumice that takes the place of the potash contains protoxide of
iron, it will also absorb oxygen. In both cases the oxygen increases the
weight of the carbonic acid.
Every experimenter who has been compelled to repeat the weighing of a
somewhat complicate piece of apparatus, with an interval of several
hours between, knows how many inaccuracies he is exposed to if he is
compelled to take into calculation the changes of temperature and
pressure, and the moisture on the surface of the apparatus. After
fighting all these difficulties, and frequently in vain, the
experimenter begins to mistrust every result that depends only on
difference in weight, and to prefer those methods whereby the substance
to be estimated can be isolated, so that it can be seen and handled,
weighed or measured, in a free state, and in its own natural condition.
The classical experiments of Thenard, of Th. de Saussure, of Messrs.
Boussingault, on the quantity of carbonic acid in the air, are well
known to every one: they need only to be organized, repeated, and
multiplied.
J. Reiset, who has conducted a long and tedious series of experiments on
this subject, has adopted a process that seems to offer every guarantee
of accuracy. The air that furnishes the carbonic acid is aspirated
through the absorption apparatus by two aspirators of 600 liters
capacity. The temperature and pressure of the air are carefully
measured. The carbonic acid is absorbed by baryta water in three bulb
apparatus. The last bulb, which serves as a check to control the
operation, remains clear, and proves that no binoxide of barium
is formed. The baryta water used is titrated before and after the
operation, and from the difference is calculated the quantity of
carbonate formed, and hence of the carbonic acid.
These tedious experiments, which varied in duration from 6 to 25 hours,
require at least two days of continuous labor. They were repeated
193 times by Reiset in 1872, 1873, and 1879. They were made in still
weather, and in violent winds and storms. The air was taken at the
sea-shore, in the middle of the fields, on the level earth, during
harvests, in the forests, and in Paris. Under such varied conditions,
the quantity of carbonic acid varied but little; the numbers obtained
were between 2.94 and 3.1, which may be taken as a general average of
the carbonic acid in the air.
The quantity of carbonic acid in the free atmosphere is tolerably
constant, which must necessarily be the case according to Schloesing's
proposed relation between the bi-carbonate of lime in the sea and the
carbonic acid in the air. The only cause that seems at all competent to
change the geological quantity of carbonic acid in the atmosphere is
the formation of fog. As the aqueous vapors condense, they collect the
carbonic acid; and the foggy air, as a rule, is more heavily laden with
this gas than ordinary air.
It is not surprising that there is less carbonic acid in the air
collected on clear summer days, in the midst of clover, etc., that is in
an active reducing furnace; if anything is surprising, it is that the
quantity of carbonic acid does not sink below 2.8.
It is also a matter for surprise that in Paris, among so many sources of
carbonic acid, the furnace fires, the respiration of men and animals,
and the spontaneous decomposition and decay of organic substances, the
quantity of carbonic acid does not exceed 3.5.
If, then, the great general mean of normal atmospheric carbonic acid
deviates but little from 2.9 or 3.0, it is not doubtful that under local
conditions, in closed places, and under exceptional meteorological
conditions, considerable variations may occur in these proportions. But
these variations do not affect the general laws of the composition of
the atmosphere.
There are two entirely distinct points from which the measurement of the
atmospheric carbonic acid may be contemplated.
The first consists in considering it as a geological element which
belongs to the gaseous envelope of the earth in general, and it leads us
to express the general relation of carbonic acid to the quantity of air,
as about three volumes in 10,000.
The second, which relates to accidental and local phenomena, to the
activity of man and beast, to the effect of fires and of decomposing
organic matter, to volcanic emanations, and finally to the action of
clouds and rain, permits us to recognize the changes which can occur
in air exposed to the influences mentioned, and to a certain extent
confined. Without denying that it is of interest from a meteorological
and hygienic standpoint, it does not take the same rank as first.
J. Reiset's experiments, by their number, accuracy, the large volumes
employed, and the interval of years that separate them, have definitely
established two facts on which the earth's history must depend: the
first is, that the percentage of carbonic acid in the air scarcely
changes; the second, that it differs but little from three
ten-thousandths by volume.
These results are fully confirmed by the results which were obtained by
Franz Schulze, in Rostock, in 1868, 1869, 1870, and 1871. The averages
which he got, with very small variation, were 2.8668 for 1869, 2.9052
for 1870, and 3.0126 for 1871.
More recently Muentz and Aubin have analyzed air collected on the plains
near Paris, on the Pic du Midi, and on the top of Puy-de-Dome. Their
results agree with those published by Reiset and Schulze.
The grand average of carbonic oxide in the air seems to be tolerably
fixed, but after this starting-point is established it remains to study
the variations that it is capable of, not from local causes, which are
of little importance, but from general causes connected with large
movements of the air. Upon this study, which demands the co-operation of
a definite number of observers stationed at different and distant
points of the earth, the experiments being made simultaneously and by
comparable methods.
M. Dumas called the attention of the Academy to this point, in
connection with its mission of selecting suitable stations for observing
the transit of Venus. The process and apparatus of Muentz and Aubin
offer the means adapted for making these experiments, and seem
sufficient to solve the problem which science proposes, of determining
the present quantity of carbonic acid in the air.
If these experiments yield satisfactory results, as we have good reasons
to believe they will, it is to be hoped that annual observations will be
made in properly-chosen places, so as to determine the variations which
may possibly take place in the relative quantity of atmospheric carbonic
acid during the coming century.--_Compt. Rend_., p. 589.
[Although this proposition was made by a Frenchman to his fellow
scientists, would it not be well for some American to accept the
challenge, and bring it before the coming meeting of the American
Association for the Advancement of Science, in the hope that we,
too, may contribute our mite of effort in the same direction?--_Ed.
Knowledge_.]
* * * * *
THE INFLUENCE OF AQUEOUS VAPOR ON THE EXPLOSION OF CARBONIC OXIDE AND
OXYGEN.
[Footnote: Read before the British Association, Southampton Meeting,
Section B, 1882.]
By HAROLD B. DIXON, M.A., Millard Lecturer in Chemistry, Balliol and
Trinity Colleges, Oxford.
Two years ago I had the honor of showing before the Chemical Section of
the British Association some experiments, in which a well-dried mixture
of carbonic oxide and oxygen was submitted to electric sparks without
exploding.[1] It was further shown that the introduction of a very
minute quantity of aqueous vapor into the non-explosive mixture was
sufficient to cause explosive combination between the gases when the
spark was passed. The hypothesis advanced to account for the observed
facts was that carbonic oxide does not unite directly with oxygen at
a high temperature, but only indirectly through the intervention of
water-vapor present, a molecule of water being decomposed by one of
carbonic oxide to form a molecule of carbonic acid and one of free
hydrogen, and the latter uniting with the oxygen to re-form a molecule
of water, which again undergoes the same cycle of changes, till all the
oxygen is transferred to the carbonic oxide:
H_{2}O + CO = H_{2} + CO_{2}
H_{2} + O = H_{2}O
[Footnote 1: "Report of British Association," 1880, p. 503.]
For such a series of reactions a _comparatively_ few molecules of water
would suffice, and the change produced by their alternate reduction and
oxidation would come under the old term of "catalytic action," inasmuch
as the few water molecules present at the beginning are found in the
same state at the completion of the reaction.
The truth of this hypothesis has since been confirmed by experiments I
have made on the incomplete combustion of mixtures of carbonic oxide and
hydrogen; and on the velocity of explosion of carbonic oxide and oxygen
with varying proportions of aqueous vapor. I therefore thought a
description of the more convenient methods lately devised as lecture
experiments for showing the influence of water on the combustion of
carbonic oxide would not be uninteresting to the Section.
A glass tube from 18 inches to 2 feet long, closed at one end, and
provided with platinum wires, is bent near its open end so that the
shorter arm makes an angle of about 60 deg. with the longer arm. The tube,
held by a clamp, is heated in a Bunsen flame, and is then filled with
mercury heated to about 130 deg. C. The mixture of gases is then made to
displace a portion of the mercury by forcing it through a fine tube,
which is connected by a steel cap to the eudiometer of McLeod's gas
apparatus, and passes down through the mercury in the shorter arm of the
experimental tube. When a sufficient quantity of the gaseous mixture
has been collected in the longer arm, some dry phosphoric oxide is
introduced in the following way: A small glass tube is heated, packed
with the dry powder, and pushed down into the shorter arm of the
experimental tube. With a hot glass rod the phosphoric oxide is pushed
out at the bottom of the small tube, and passes up into the gaseous
mixture in the longer arm. After standing for a few hours in contact
with the phosphoric oxide, the gases may be submitted to strong sparks
from a Leyden jar without igniting. Care must be taken that none of the
oxide comes in contact with the platinum wires, for if any sticks to
the wires it becomes heated by the passage of the sparks, and gives off
enough water to determine the explosion. In this way I have prepared
several specimens of a non-explosive mixture of carbonic oxide and
oxygen in the proper proportions to form carbonic acid. Some of these
tubes have been submitted without explosion to sparks from a large
Leyden jar, to a continuous succession of sparks from a Holtz machine,
and to the discharge of a Ruhmkorff's coil, that heated the platinum
wires between which it passed to bright redness. Other tubes which
withstood the passage of the sparks from a Leyden jar, when submitted
to the discharge of the coil, exploded after a few seconds when the
platinum wires became red-hot. This I think may probably be attributed
to hydrogen, occluded by the platinum, being given off on heating, and
forming steam with the oxygen present.
For an easy and striking lecture experiment, I employ a tube open
at both ends and bent like a W. The two open arms are short and the
platinum wires are fixed at the highest bend. The tube is filled with
hot mercury--one of the ends being closed by a caoutchouc stopper for
the purpose--and a dry mixture of 5 volumes of air and 2 volumes of
carbonic oxide is introduced into the bent tube over the mercury. A
little phosphoric oxide is passed up one arm. After a few minutes the
gases may be submitted to the spark without exploding. A little water
may then be introduced through a pipette into the other arm; and if the
spark is passed directly the gases ignite in the wet and not in the dry
arm of the tube.
The admixture of the inert nitrogen renders a larger quantity of aqueous
vapor necessary for the explosion than when only carbonic oxide and
oxygen in proper proportion are present.
* * * * *
COMPOSITION OF BEERS MADE PARTLY FROM RAW GRAIN.
At the present time English brewers are being denounced for substituting
properly-prepared maize, rice, and other raw grain for barley malt, and
the beers produced partly from such materials are described as being
very inferior, and even injurious to health. That such denunciations are
altogether unwarranted is evident to all who have paid any attention to
the subject, and are acquainted with the chemical changes involved in
brewing, and with the composition of the resulting beers. Unfortunately
but few comparative analyses have been published of beers made solely
from malt and beers made from malt in conjunction with raw grain, and
therefore such wild assertions as were recently uttered in the House of
Commons have remained unanswered. A German chemist, J. Hanamann, some
time since made a series of analyses of beers brewed partly from raw
grain, and his results completely controvert the theory that raw grain
beers essentially differ in composition from malt beers. Four worts were
made by the decoction system of mashing: A entirely from barley malt; B
from 60 per cent. of malt and 40 per cent. of maize; C from 60 per cent.
of malt and 40 per cent. of rice; and D from 60 per cent of malt and 40
per cent. of pure starch. The analyses of these respective worts gave
the following results:
A B C D
Sugar............... 4.96 4.08 4.84 4.87
Dextrine............ 6.05 6.83 6.35 6.60
Total extract....... 12.29 12.27 12.30 12.32
Albuminoids......... 0.82 0.78 0.68 0.42
Other substances.... 0.46 0.58 0.43 0.43
It will be seen that these worts vary very little in composition, the
chief points of difference being that those made partly from raw grain
are more dextrinous and contain less albuminoids than the wort made from
malt alone. The process of brewing was then continued as usual, and
after fermentation the resulting beers were again analyzed with the
following results:
A B C D
Alcohol............. 2.71 2.76 2.90 3.19
Sugar............... 1.05 1.12 0.98 0.35
Dextrine............ 4.54 4.31 4.42 4.74
Extract............. 6.59 6.48 6.25 5.91
Albuminoids......... 0.43 0.39 0.33 0.28
Other substances ... 0.57 0.66 0.52 0.54
It will be observed that the beers made partly from raw grain are
slightly more alcoholic, but in other respects differ but very little
from the pure malt beer, but none of them can in any way be pronounced
as really inferior or unwholesome. The beer made partly from maize is,
in fact, hardly to be distinguished in chemical composition from that
made solely from malt. These worts and beers were brewed upon the German
system, but analogous results would undoubtedly be obtained with beers
brewed from the like materials on the English system. We hope soon to be
in a position to publish some comparative analyses of beers brewed in
this country from malt combined with different kinds of raw grain; but
the analyses which we have now quoted constitute a sufficient refutation
to those who assert that brewers using raw grain are producing an
injurious or even an inferior quality of beer.--_Brewers' Guardian_.
* * * * *
DOUBLE BUTTERCUPS.
Among early summer flowers in open borders few are prettier than the
double-flowered kinds of ranunculus of the herbaceous type. Having been
established favorites for ages, most of them are familiar to us, and
poor indeed is that hardy plant border which does not contain a good
healthy tuft of what are termed Fair Maids of France, or Bachelor's
Buttons, the doubled flowered variety of _R. aconitifolius_. The small,
pure white rosette-like flowers produced so plentifully, and in such
a graceful manner, make it an extremely pretty, and, though common,
valuable plant, particularly useful in a cut state. It is one of the
kinds shown in the annexed engraving. Of double crowfoots there are
three others, the types of which are _R. bulbosus, acris_, and _repens_.
All these are very pretty, having bright yellow, compact, rosette-like
flowers, as perfect in form as that of some of the finest sorts of the
Asiatic or Persian ranunculus of the florists. Both the double _R.
acris_ and _repens_ are profuse flowerers, but _R. bulbosus_ is not so;
it, however, bears much larger flowers than either of the others, and
on this account is named _R. speciosus_. These four plants are
indispensable, yielding, as they do, flowers in such abundance and in
such long succession. In order to enable them to develop fully
they require good culture, a good, deep loamy soil, enriched with
well-decayed manure, and if the border be moist, so much the better,'for
these ranunculuses delight in a cool, moist soil. Treated liberally in
this way, these double buttercups are indeed fine plants.--_W. G., in
The Garden_.
[Illustration: DOUBLE BUTTERCUPS.]
* * * * *
LIGUSTRUM QUIHOUI.
This is a Chinese species, at present little known in this country. It
forms a low bush with spreading wiry purplish downy branches, and loose
terminal panicles of white flowers. Its peculiar spreading habit, dark
green leaves, and abundant flowers render it a desirable acquisition to
the shrubbery. It is quite hardy.--_The Gardeners' Chronicle_.
[Illustration: LIGUSTRUM QUIHOUI.]
* * * * *
RAPHIOLEPIS JAPONICA.
This handsome Japanese shrub is not an uncommon plant in greenhouses, in
which it is generally known under the garden name of _R. ovata_. It is,
however, perfectly hardy, and it is with the view of making that fact
known that we produce the annexed illustration of it, which represents a
spray lately sent to us by Messrs. Veitch from their nursery at Coombe
Wood, where the plant has withstood the full rigor of our climate for
some years past. The Coombe Wood Nursery is not very well sheltered, and
the soil is not of the lightest description; the plant may, therefore,
be said to have a fair trial out-of-doors. We have also met with it in
the open air in other places besides Coombe Wood, and if we remember
rightly, Mr. G.F. Wilson has a fine old bush of it on his rockery which
abounds with shrubs of a similar character, all apparently at home. This
shrub is of low growth, somewhat bushy in habit, and rather sparsely
furnished with oval leaves of a leathery texture. It produces its
flowers in early summer, and when a good-sized bush, well covered with
clusters of white blossoms resembling those of some species of Crataegus,
it has a handsome appearance, and, like most other rosaceous shrubs,
powerfully fragrant. Those who possess duplicate plants of it would do
well to try it in the open in some sheltered spot, and if in a high and
dry position so much the better. This species is called also in the
gardens by its synonym, _R. integerrima_ There are three other kinds
of Raphiolepis in cultivation, viz., _R. indica, R. rubra_, and _R.
salicifolia_, but only the last named one is generally known. It too
is a handsome shrub, readily distinguished by the long, willow-like
foliage. Its flowers are much the same as those of _R. japonica_, but
more plentifully produced. We have no instance of its having stood out
like its congener, and we doubt if it is so hardy, seeing that it is
a Chinese plant. Perhaps some of our readers can enlighten us on the
point.--_W.G., in The Garden_.
[Illustration: FLOWERING SPRAY OF RAPHIOLEPIS JAPONICA.]
* * * * *
RIVINA LAEVIS.
The brilliant little scarlet berries of this plant render it, when well
grown, one of the prettiest of ornaments for the hothouse, conservatory,
or even for a warm room. It is quite easily managed, stray seeds of it
even growing where they fall, and making handsome specimens. For indoor
decoration few subjects are more interesting, and a few plants may be so
managed as to have them in fruit in succession all the year round. Any
kind of soil will answer for this Rivina. Cuttings of it strike freely,
but it is easiest obtained from seeds. Either one plant or three may
occupy a 6 in. pot, and that is the best size for table decoration.
Usually it is best to raise a few plants every year and discard the old
stock, but some may be retained for growing into large specimens. These
should be cut back before they are started into growth. The berries
yield a fine, but fugitive red color. Miller says that he made
experiments with the juice for coloring flowers, and succeeded extremely
well, thus making the tuberose and the double white narcissus variegated
in one night. Of this species there is a variety with yellow berries
which are not quite so handsome as the red, though very attractive. _R.
humilis_ differs from laevis in having hairy leaves, those of laevis being
quite smooth. It also differs in the duller red color of the
berries, laevis being much the prettier. Both are natives of the West
Indies.--_R.I.L., in The Garden_.
* * * * *
APPLES IN STORE.
Apples always, whether in barrels or piles, when the temperature is
rising so that the surrounding air is warmer than the apples, condense
moisture on the surface and become quite moist and sometimes dripping
wet, and this has given the common impression that they "sweat," which
is not true. As they come from the tree they are plump and solid,
full of juice; by keeping, they gradually part with a portion of this
moisture, the quantity varying with the temperature and the circulation
of air about them, and being much more rapid when first picked than
after a short time, and by parting with this moisture they become
springy or yielding, and in a better condition to pack closely in
barrels; but this moisture never shows on the surface in the form of
sweat. In keeping apples, very much depends upon the surroundings; every
variation in temperature causes a change in the fruit, and hastens
maturity and decay, and we should strive to have as little change as
possible, and also have the temperature as low as possible, so the
apples do not freeze. Then, some varieties keep much better in open bins
than others; for instance, the Greening is one of the best to store in
bins. A very good way for storing apples is to have a fruit-room that
can be made and kept at from 32 deg. to 28 deg., and the air close and pure,
put the apples in slatted boxes, not bins, each box holding about one
barrel, and pile them in tiers, so that one box above rests on two
below, and only barrel when ready to market; but this is an expensive
way, and can only be practiced by those with limited crops of apples,
and it is not at all practicable for long keeping, because in this way
they lose moisture much more rapidly than when headed close in barrels,
and become badly shriveled.
All things considered, there is no way of keeping apples quite so good
and practicable as packing in light barrels and storing in cool cellars;
the barrel forms a room within a room, and prevents circulation of air
and consequent drying and shrinking of the fruit, and also lessens the
changes of temperature, and besides more fruit can be packed and stored
in a given space than in any other way. The poorest of all ways is the
large open bin, and the objections are: too much fruit in contact; too
much weight upon the lower fruit; and too much trouble to handle and
sort when desirable to market. It was formerly the almost universal
custom in Western New York to sort and barrel the apples as fast as
picked from the trees, heading up at once and drawing to market or
piling in some cool place till the approach of cold weather, and then
putting in cellars. By this method it was impossible to prevent leaves,
twigs, and other dirt from getting into the bin, and it was difficult to
properly sort the fruit, and if well sorted, occasionally an apple, with
no visible cause, will entirely and wholly rot soon after packing. Some
varieties are more liable to do this than others, but all will to some
extent; this occurs within a week or ten days after picking, and, when
barreled, these decayed apples are of course in the barrels, and help to
decay others. Although packed ever so well and pressed ever so tight,
the shrinking of the fresh-picked fruit, soon makes them loose, and
nothing is so bad in handling apples as this. Altogether this was a very
untidy method of handling apples, and has been entirely abandoned for a
better.
The very best method depends a good deal upon the quantity to be
handled; if only a few hundred barrels, they can be put in open barrels
and stored on the barn floor. Place empty barrels on a log-boat or old
sled; take out the upper head and place it in the bottom of the barrel;
on picking the apples put them, without sorting, directly into these
barrels, and when a load is filled, draw to the barn and place in tiers
on end along one side of the floor; when one tier is full lay some
strips of boards on top and on these place another tier of barrels; then
more boards and another tier; two men can easily place them three tiers
high, and an ordinary barn floor will in this way store a good many
barrels of apples. Where many hundreds or thousands of barrels are
grown, it is a good plan to build houses or sheds in convenient places
in the orchard for holding the apples as picked; these are built on
posts or stones, about one foot from the ground; floors, sides, and ends
should be made of strips about four inches wide and placed one inch
apart, and the roof should project well on every side. The apples, as
picked, are drawn to these in boxes or barrels and piled carefully on
the floors, about three feet deep. Where these houses are not provided,
the next best way is to pile the apples, as picked, on clean straw under
the trees in the deepest shade to be found.
After lying in any one of these positions about ten days they should
be carefully sorted and packed in clean barrels, placing at least two
layers on the bottom of the barrels, with stems down; after this fill
full, shaking moderately two or three times as the tilling goes on, and,
with some sort of press, press the head down, so that the apples shall
remain firm and full under all kinds of handling. Apples may be pressed
too much as well as too little. If pressed so that many are broken, and
badly broken, they will soon get loose and rattle in the barrels, and
nothing spoils them sooner than this. What we want is to have them just
so they shall be sure to remain firm, and carefully shaking so as to
have them well settled together, has as much to do with their remaining
firm as the pressing down of the head. After the barrels are filled and
headed they should at once be placed on their sides in a barn or shed,
or in piles, covered with boards, from sun and rain, or if a fruit-house
or cellar is handy they may at once be placed therein; the object should
be to keep them as cool and at as even a temperature as possible. In all
the operations of handling apples from picking to market, remember that
carelessness and harshness always bruise the fruit, and that every
bruise detracts much from its keeping and market value; and remember
another thing, that "Honesty is the best policy."--_J.S. Woodward, in
N.Y. Tribune_.
* * * * *
ON DETERMINING THE SUN'S DISTANCE BY A NEW METHOD.
By T.S.H. EYTINGE, Cainsville, Canada.
It is well known that the sun's distance has been determined from the
velocity of light. It has been found, by terrrestrial experiments, about
how fast light travels, and, knowing from certain astronomical phenomena
the time light requires to pass from the sun to the earth, we have been
able to determine the sun's distance.
There are several methods of determining the velocity of light, but
hitherto only two plans have been used to detect the time light occupies
in passing from the sun to the earth. This time was first discovered
by observations of the satellites of Jupiter. It was found that the
interval between the eclipses of these bodies was not always the
same--that the eclipses occurred earlier when Jupiter was nearest the
earth, and later when he was at his greatest distance. Roemer, a Danish
astronomer, first detected the cause of this variation. The second
method by which this time has been found is the aberration of stellar
light. This refined method was detected by the great English astronomer
Bradley.
About two years ago it occurred to me that a third method can be used
to solve this important problem. My plan is this: It is well known that
many variable stars, such as Algol, [sigma] Librae, U Coronae, and the
remarkable variable D.M. + 1.3408 deg., discovered by Mr. E.F. Sawyer,
fluctuate at regular intervals. Now, I believe it is possible to
determine very accurately the intervals between these changes, and,
by noting the change of time in these intervals, when the earth is in
different points of its orbit, we get the time light requires to cross
that orbit. For, as in the case of the satellites of Jupiter, when the
star is "in opposition," the changes will occur earlier than when it is
in conjunction or approaching that point. I have recently put this plan
to the test, and hope before long to make known the results.
In detecting the changes of variables, I have attempted to substitute,
in place of the ordinary eye observations, a very delicate thermopile,
which registers the changes in the star's heat. So far as I know, this
is the first application of the thermopile to variables.
* * * * *
PROFESSOR HAECKEL ON DARWIN.
In _Nature_ appears a report of the remarkable address given by
Professor Haeckel at the recent Eisenach meeting of the German
Association of Naturalists on the theories of Darwin, Goethe, and
Lamarck. The address is mainly devoted to Darwin and Darwinism, and of
both, we need scarcely say, Professor Haeckel has the highest estimate.
He said:
"When, five months ago, the sad intelligence reached us by telegraph
from England that on April 19 Charles Darwin had concluded his life
of rich activity there thrilled with rare unanimity through the whole
scientific world the feeling of an irreparable loss. Not only did the
innumerable adherents and scholars of the great naturalist lament the
decease of the head master who had guided them, but even the most
esteemed of his opponents had to confess that one of the most
significant and influential spirits of the century had departed. This
universal sentiment found its most eloquent expression in the fact that
immediately after his death the English newspapers of all parties, and
pre-eminently his Conservative opponents, demanded that the burial-place
of the deceased should be in the Valhalla of Great Britain, the national
Temple of Fame, Westminster Abbey; and there, in point of fact, he found
Back to Full Books
|