Scientific American Supplement, No. 586, March 26, 1887 by Various
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Various >> Scientific American Supplement, No. 586, March 26, 1887
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The following is the plan by which I have succeeded best in the production
of transparencies:
[Illustration]
B is a lamp with a circular wick, which burns petroleum and gives a good
body of light.
C is a frame for holding the negative, on the opposite side of which is a
double convex lens facing the light.
D is the camera and lens.
All these must be placed in a line, so that the best part of the light, the
center of the condenser, and the lens are of equal height.
The method of working is as follows: The lamp, B, is placed at such a
distance from the condenser that the rays come to a focus and enter the
lens; the negative is then placed in the frame, the focus obtained, and the
size of reduction adjusted by moving the camera nearer to or further from
the condenser and negative. In doing this no attention need be paid to the
light properly covering the field, as that cannot be adjusted while the
negative is in its place. When the size and focus are obtained, remove the
negative, and carefully move the lamp till it illuminates the ground glass
equally all over, by a disk of light free from color.
The negative can then be replaced, and no further adjustment will be needed
for any further reproduction of the same size.
There is one point that requires attention: The lens used in the camera
should be a doublet of about 6 inch focus (in reproducing 81/2 x 61/2 or
smaller sizes), and the stop used must not be a very small one, not less
than 1/2 inch diameter. If a smaller stop is used, an even disk of light is
not obtained, but ample definition is obtainable with the size stop
mentioned.
In the arrangement described, a single lens is used for the condenser, not
because it is better than a double one, as is general for such purposes,
but because it is quite sufficient for the purpose. Of course, a large
condenser is both expensive and cumbersome. There is, therefore, no
advantage in using a combination if a single lens will answer.
In reproducing lantern pictures from half-plate negatives, the time
required on my lantern plates is from two to four minutes, using 6 inch
condenser. For whole plate negatives, from two to six minutes with a 9 inch
condenser. In working in this way it is easy to be developing one picture
while exposing another.
The condenser must be of such a size that it will cover the plate from
corner to corner. The best part of an 81/2 x 61/2 negative will be covered by a
9 inch condenser, and a 61/2 x 43/4 by a 6 inch condenser.
With this arrangement it will be easy to reproduce from half or whole plate
negatives or any intermediate sizes quite independently of daylight.
* * * * *
EXPERIMENTS IN TONING GELATINO-CHLORIDE PAPER.
From the _Photographic News_ we take the following: The use of paper coated
with a gelatino-citro-chloride emulsion in place of albumenized paper
appears to be becoming daily more common. Successful toning has generally
been the difficulty with such paper, the alkaline baths commonly in use
with albumenized having proved unsuitable for toning this paper. On the
whole, the bath that has given the best results is one containing, in
addition to gold, a small quantity of hypo and a considerable quantity of
sulphocyanide of ammonium. Such a bath tones very rapidly, and gives most
pleasing colors. It appears, moreover, to be impossible to overtone the
citro-chloro emulsion paper with it in the sense that it is possible to
overtone prints on albumenized paper with the ordinary alkaline bath. That
is to say, it is impossible to produce a slaty gray image. The result of
prolonged toning is merely an image of an engraving black color. Of this,
however, we shall say more hereafter. We wish first of all to refer to an
elaborate series of experiments by Lionel Clark on the effects of various
toning baths used with the gelatino-citro-chloride paper.
The results of these experiments we have before us at the time of writing,
and we may at once say that, from the manner in which the experiments have
been carried out and in which the results have been tabulated, Lionel
Clark's work forms a very useful contribution to our photographic
knowledge, and a contribution that will become more and more useful, the
longer the results of the experiments are kept. A number of small prints
have been prepared. Of these several--in most cases, three--have been toned
by a certain bath, and each print has been torn in two. One-half has been
treated with bichloride of mercury, so as to bleach such portion of the
image as is of silver, and finally the prints--the two halves of each being
brought close together--have been mounted in groups, each group containing
all the prints toned by a certain formula, with full information tabulated.
The only improvement we could suggest in the arrangement is that all the
prints should have been from the same negative, or from only three
negatives, so that we should have prints from the same negatives in every
group, and should the better be able to compare the results of the toning
baths. Probably, however, the indifferent light of the present season of
the year made it difficult to get a sufficiency of prints from one
negative.
The following is a description of the toning baths used and of the
appearance of the prints. We refer, in the mean time, only to those halves
that have not been treated with bichloride of mercury.
1.--Gold chloride (AuCl_{3})........... 1 gr.
Sulphocyanide of potassium......... 10 gr.
Hyposulphite of soda............... 1/2 gr.
Water.............................. 2 oz.
The prints are of a brilliant purple or violet color.
2.--Gold chloride...................... 1 gr.
Sulphocyanide of potassium......... 10 gr.
Hyposulphite of soda............... 1/2 gr.
Water.............................. 4 oz.
There is only one print, which is of a brown color, and in every way
inferior to those toned with the first bath.
3.--Gold chloride...................... 1 gr.
Sulphocyanide of potassium......... 12 gr.
Hyposulphite of soda............... 1/2 gr.
Water.............................. 2 oz.
The prints toned by this bath are, in our opinion, the finest of the whole.
The tone is a purple of the most brilliant and pleasing shade.
4.--Gold chloride...................... 1 gr.
Sulphocyanide of potassium......... 20 gr.
Hyposulphite of soda............... 5 gr.
Water.............................. 2 oz.
There is only one print, but it is from the same negative as one of the No.
3 group. It is very inferior to that in No. 3, the color less pleasant, and
the appearance generally as if the details of the lights had been bleached
by the large quantity either of hypo or of sulphocyanide of potassium.
5.--Gold chloride...................... 1 gr.
Sulphocyanide of potassium......... 50 gr.
Hyposulphite of soda............... 1/2 gr.
Water.............................. 2 oz.
Opposite to this description of formula there are no prints, but the
following is written: "These prints were completely destroyed, the
sulphocyanide of potassium (probably) dissolving off the gelatine."
6.--Gold chloride...................... 1 gr.
Sulphocyanide of potassium......... 20 gr.
Hypo............................... 5 gr.
Carbonate of soda.................. 10 gr.
Water.............................. 2 oz.
This it will be seen is the same as 4, but that the solution is rendered
alkaline with carbonate of soda. The result of the alkalinity certainly
appears to be good, the color is more pleasing than that produced by No. 4,
and there is less appearance of bleaching. It must be borne in mind in this
connection that the paper itself is strongly acid, and that, unless special
means be taken to prevent it, the toning bath is sure to be more or less
acid.
7.--Gold chloride...................... 1 gr.
Acetate of soda.................... 30 gr.
Water.............................. 2 oz.
The color of the prints toned by this bath is not exceedingly pleasing. It
is a brown tending to purple, but is not very pure or bright. The results
show, however, the possibility of toning the gelatino-chloro-citrate paper
with the ordinary acetate bath if it be only made concentrated enough.
8.--Gold chloride...................... 1 gr.
Carbonate of soda.................. 3 gr.
Water.............................. 2 oz.
Very much the same may be said of the prints toned by this bath as of those
toned by No. 7. The color is not very good, nor is the toning quite even.
This last remark applies to No. 7 batch as well as No. 8.
9.--Gold chloride...................... 1 gr.
Phosphate of soda.................. 20 gr.
Water.............................. 2 oz.
The results of this bath can best be described as purplish in color. They
are decidedly more pleasing than those of 7 or 8, but are not as good as
the best by the sulphocyanide bath.
10.--Gold chloride..................... 1 gr.
Hyposulphite of soda.............. 1/2 oz.
Water............................. 2 oz.
The result of this bath is a brilliant brown color, what might indeed,
perhaps, be best described as a red. Two out of the three prints are much
too dark, indicating, perhaps, that this toning bath did not have any
tendency to reduce the intensity of the image.
The general lesson taught by Clark's experiments is that the sulphocyanide
bath gives better results than any other. A certain proportion of the
ingredients--namely, that of bath No. 3--gives better results than any
other proportions tried, and about as good as any that could be hoped for.
Any of the ordinary alkaline toning baths may be used, but they all give
results inferior to those got by the sulphocyanide bath. The best of the
ordinary baths is, however, the phosphate of soda.
And now a word as to those parts of the prints which have been treated with
bichloride of mercury. The thing that strikes us as remarkable in
connection with them is that in them the image has scarcely suffered any
reduction of intensity at all. In most cases there has been a disagreeable
change of color, but it is almost entirely confined to the whites and
lighter tints, which are turned to a more or less dirty yellow. Even in the
case of the prints toned by bath No. 10, where the image is quite red, it
has suffered no appreciable reduction of intensity.
This would indicate that an unusually large proportion of the toned image
consists of gold, and this idea is confirmed by the fact that to tone a
sheet of gelatino-chloro-citrate paper requires several times as much gold
as to tone a sheet of albumenized paper. Indeed, we believe that, with the
emulsion paper, it is possible to replace the whole of the silver of the
image with gold, thereby producing a permanent print. We have already said
that the print may be left for any reasonable length of time in the toning
bath without the destruction of its appearance, and we cannot but suppose
that a very long immersion results in a complete substitution of gold for
silver.
* * * * *
THE "SENSIM" PREPARING BOX.
Fig. 1 shows a perspective view of the machine, Fig. 2 a sectional
elevation, and Fig. 3 a plan. In the ordinary screw gill box, the screws
which traverse the gills are uniform in their pitch, so that a draught is
only obtained between the feed rollers and the first gill, between the last
gill of the first set and the first of the second, and between the last
gill of the second set and the delivery roller. As thus arranged, the gills
are really not active workers after their first draw during the remainder
of their traverse, but simply carriers of the wool to the next set. It is
somewhat remarkable, as may indeed be said of every invention, that this
fact has only been just observed, and suggested an improvement. There is no
reason why each gill should not be continuously working to the end of the
traverse, and only cease during its return to its first position. The
perception of this has led to several attempts to realize this
improvement. The inventor in the present case seems to have solved the
problem in a very perfect manner by the introduction of gill screws of a
gradually increasing pitch, by which the progress of the gills, B, through
the box is constantly undergoing acceleration to the end, as will be
obvious from the construction of the screws, A and A, until they are
passed down in the usual manner, and returned by the screws, C and C,
which are, as usual, of uniform pitch. The two sets of screws are so
adjusted as to almost meet in the middle, so that the gills of the first
set finish their forward movement close to the point where the second
commence. The bottom screws, C, of the first set of gills, B, are actuated
by bevel wheels on a cross shaft engaging with bevel wheels on their outer
extremity, the cross shaft being geared to the main shaft. The screws, C,
of the second set of gills from two longitudinal shafts are connected by
bevel gearing to the main shaft. Intermediate wheels communicate motion
from change wheels on the longitudinal shafts to the wheels on the screw,
C, traversing the second set of gills.
[Illustration: FIG. 1.--"SENSIM" SCREW GILL PREPARING BOX.]
The feed and delivery rollers, D and E, are operated by gearing connected
to worms on longitudinal shafts. These worms engage with worm wheels on
cross shafts, which are provided at their outer ends with change wheels
engaging with other change wheels on the arbors of the bottom feed and
delivery rollers, D and E.
[Illustration: FIG. 2.--"SENSIM" SCREW GILL--SECTIONAL ELEVATION.]
The speeds are so adjusted that the fibers are delivered to the first set
of gills at a speed approximately equal to the speed at which these start
their traverse. The gills in the second set begin their journey at a pace
which slightly exceeds that at which those of the first finish their
traverse. These paces are of course regulated by the class and nature of
the fibers under operation. The delivery rollers, E, take off the fibers at
a rate slightly exceeding that of the gills delivering it to them.
[Illustration: FIG. 3.--"SENSIM" SCREW GILL--PLAN.]
In the ordinary gill box, the feed and delivery rollers are fluted, in
order the better to retain in the first instance their grip upon the wool
passing through, and in the second to enable them to overcome any
resistance that might be offered to drawing the material. It thus often
happens in this class of machines that a large percentage of the fibers are
broken, and thus much waste is made. The substitution of plain rollers in
both these positions obviates most of this mischief, while in combination
with the other parts of the arrangement it is almost precluded altogether.
It will be obvious from what we have said that the special features of this
machine, which may be summarized as, first, the use of a screw thread of
graduated pitch; second, an increased length of screw action and an
additional number of fallers; and third, the use of light plain rollers in
place of heavy fluted back and front rollers, enable the inventor to justly
claim the acquisition of a number of advantages, which may be enumerated as
follows:
The transformation of the gills from mere carriers into constant workers
during the whole of their outward traverse, by which the work is done much
more efficiently, more gently, and in greater quantity than by the old
system with uniformly pitched screws. A great improvement in the quality of
the work, resulting from the breakage of fiber being, if not entirely
obviated, nearly. An increased yield and better quality of top, owing to
the absence of broken fiber, and consequent diminution of noil and waste.
The better working of cotted wools, which can be brought to a proper
condition with far more facility and with diminished risk of breaking pins
than before. A saving in labor, space, and plant also results from the fact
that the wool is as well opened and straightened for carding with a passage
through a pair of improved boxes as it is in going through four of the
ordinary ones, while the quantity will be as great. Owing to the first
feature referred to, which distributes the strain over all the gills, a
greater weight of wool can be put into them and a higher speed be worked.
The space occupied and the attendance required is only about half that of
boxes required to do the same amount of work on the old system. Taking the
flutes out of the feed and delivery rollers, and greatly diminishing their
weight, it is estimated will reduce by 90 per cent. the wear and tear of
the leather aprons, and thus to that extent diminish a very heavy annual
outlay incident to the system generally in vogue. A considerable saving of
power for driving and of time and cost of repairs from the bending and
breakage of pins also results. Shaw, Harrison & Co., makers,
Bradford.--_Textile Manufacturer_.
* * * * *
NOTES ON GARMENT DYEING.
Black wool dresses for renewing and checked goods, with the check not
covered by the first operation, are operated upon as follows:
_Preparation or mordant for eight black dresses for renewing the color._
2 oz. Chrome.
2 " Argol or Tartar.
Or without argol or tartar, but I think their use is beneficial. Boil
twenty minutes, lift, rinse through two waters.
To prepare dye boiler, put in 2 lb. logwood, boil twenty minutes. Clear the
face same way as before described. Those with cotton and made-up dresses
sewn with cotton same operation as before mentioned, using half the
quantity of stuffs, and working cold throughout. Since the introduction of
aniline black, some dyers use it in place of logwood both for wool and
cotton. It answers very well for dippers, substituting 2 oz. aniline black
for every pound logwood required. In dyeing light bottoms it is more
expensive than logwood, even though the liquor be kept up, and, in my
opinion, not so clear and black.
_Silk and wool dresses, poplins, and woolen dresses trimmed with silk,
etc., for black_.--Before the dyeing operations, steep the goods in
hand-heat soda water, rinse through two warm waters. Discharge blues,
mauves, etc., with diluted aquafortis (nitric acid). A skilled dyer can
perform this operation without the least injury to the goods. This liquor
is kept in stoneware, or a vessel made of caoutchouc composition, or a
large stone hollowed out of five slabs of stone, forming the bottom and
four sides, braced together, and luted with caoutchouc, forming a
water-tight vessel. The latter is the most convenient vessel, as it can be
repaired. The others when once rent are past repair. The steam is
introduced by means of a caoutchouc pipe, and when brought to the boil the
pipe is removed. After the colors are discharged, rinse through three warm
waters. They are then ready to receive the mordant and the dye.
_Note_.--The aquafortis vessel to be outside the dye-house, or, if inside,
to be provided with a funnel to carry away the nitrous fumes, as it is
dangerous to other colors.
_Preparation or mordant for eight dresses, silk and wool mixed, for black._
4 lb. Copperas.
1/2 " Bluestone.
1/2 " Tartar.
Bring to the boil, dissolve the copperas, etc., shut off steam, enter the
goods, handle gently (or else they will be faced, i.e., look gray on face
when dyed) for one hour, lift, air, rinse through three warm waters.
To prepare dye boiler, bring to boil, put in 8 lb. logwood (previously
boiled), 1 lb. black or brown oil soap, shut off steam, enter goods, gently
handle for half an hour, add another pound of soap (have the soap dissolved
ready), and keep moving for another half hour, lift, finish in hand-heat
soap. If very heavy, run through lukewarm water slightly acidulated with
vitriol, rinse, hydro-extract, and hang in stove. Another method to clear
them: Make up three lukewarm waters, in first put some bleaching liquor, in
second a little vitriol, handle these two, and rinse through the third,
hydro-extract, and hang in stove.
_Note_.--This is the method employed generally in small dye-works for all
dresses for black; their lots are so small. This preparation can be kept
up, if care is taken that none of the sediment of the copperas (oxide of
iron) is introduced when charging, as the oxide of iron creates stains.
This also happens when the water used contains iron in quantity or impure
copperas. The remedy is to substitute half a gill of vitriol in place of
tartar.
_Silk, wool, and cotton mixed dresses, for black_.--Dye the silk and wool
as before described, and also the cotton in the manner previously
mentioned.
_Another method to dye the mixed silk and wool and cotton dresses black,
four dresses_.--Bring boiler to the boil, put in 3 or 4 oz. aniline black,
either the deep black or the blue black or a mixture of the two, add 1/4 gill
hydrochloric acid or sulphuric acid, or 3 oz. oxalic acid, shut off steam,
enter, and handle for half an hour, lift, rinse through water, dye the
cotton in the manner previously described.--_Dyer_.
* * * * *
FUEL AND SMOKE.
[Footnote: Second of two lectures delivered at the Royal Institution,
London, on 17th April, 1886. Continued from SUPPLEMENT, No. 585, p. 9340.]
By Prof. OLIVER LODGE.
LECTURE II.
The points to which I specially called your attention in the first lecture,
and which it is necessary to recapitulate to-day, are these: (1) That coal
is distilled, or burned partly into gas, before it can be burned. (2) That
the gas, so given off, if mixed with carbonic acid, cannot be expected to
burn properly or completely. (3) That to burn the gas, a sufficient supply
of air must be introduced at a temperature not low enough to cool the gases
below their igniting point. (4) That in stoking a fire, a small amount
should be added at a time because of the heat required to warm and distill
the fresh coal. (5) That fresh coal should be put in front of or at the
bottom of a fire, so that the gas may be thoroughly heated by the
incandescent mass above and thus, if there be sufficient air, have a chance
of burning. A fire may be inverted, so that the draught proceeds through it
downward. This is the arrangement in several stoves, and in them, of
course, fresh coal is put at the top.
Two simple principles are at the root of all fire management: (1) Coal gas
must be at a certain temperature before it can burn; and (2) it must have a
sufficient supply of air. Very simple, very obvious, but also extremely
important, and frequently altogether ignored. In a common open fire they
are both ignored. Coal is put on the top of a glowing mass of charcoal, and
the gas distilled off is for a longtime much too cold for ignition, and
when it does catch fire it is too mixed with carbonic acid to burn
completely or steadily. In order to satisfy the first condition better, and
keep the gases at a higher temperature, Dr. Pridgin Teale arranges a
sloping fire-clay slab above his fire. On this the gases play, and its
temperature helps them to ignite. It also acts as a radiator, and is said
to be very efficient.
In a close stove and in many furnaces the second condition is violated;
there is an insufficient supply of air; fresh coal is put on, and the
feeding doors are shut. Gas is distilled off, but where is it to get any
air from? How on earth can it be expected to burn? Whether it be expected
or not, it certainly does not burn, and such a stove is nothing else than a
gas works, making crude gas, and wasting it--it is a soot and smoke
factory.
Most slow combustion stoves are apt to err in this way; you make the
combustion slow by cutting off air, and you run the risk of stopping the
combustion altogether. When you wish a stove to burn better, it is
customary to open a trap door below the fuel; this makes the red hot mass
glow more vigorously, but the oxygen will soon become CO_{2}, and be unable
to burn the gas.
The right way to check the ardor of a stove is not to shut off the air
supply and make it distill its gases unconsumed, but to admit so much air
above the fire that the draught is checked by the chimney ceasing to draw
so fiercely. You at the same time secure better ventilation; and if the
fire becomes visible to the room so much the better and more cheerful. But
if you open up the top of a stove like this, it becomes, to all intents and
purposes, an open fire. Quite so, and in many respects, therefore, an open
fire is an improvement on a close stove. An open fire has faults, and it
certainly wastes heat up the chimney. A close stove may have more
faults--it wastes less _heat_, but it is liable to waste _gas_ up the
chimney--not necessarily visible or smoky gas; it may waste it from coke or
anthracite, as CO.
You now easily perceive the principles on which so-called smoke consumers
are based. They are all special arrangements or appendages to a furnace for
permitting complete combustion by satisfying the two conditions which had
been violated in its original construction. But there is this difficulty
about the air supply to a furnace: the needful amount is variable if the
stoking be intermittent, and if you let in more than the needful amount,
you are unnecessarily wasting heat and cooling the boiler, or whatever it
is, by a draught of cold air.
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