Scientific American Supplement, No. 384, May 12, 1883
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Various >> Scientific American Supplement, No. 384, May 12, 1883
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Now take portions of a similarly washed emulsion, and add to one portion
some niter, and to another some potassium bromide; on boiling these
we find that the one containing niter does not change, while that
containing the potassium bromide rapidly undergoes the changes
mentioned.
Here, then, by a direct appeal to experiment, we prove that to all
appearance comparatively useless excess of potassium bromide is really
one of the most important constituents of the emulsion.
The following table gives some interesting results respecting this
action of potassium bromide:
__________________________________________________________
Excess of potash bromide. | Time to acquire maximum |
| sensitiveness. |
--------------------------+------------------------------+
0.2 grain per ounce | no increase after six hours. |
2.0 " " | about one-half an hour. |
20.0 " " | seven minutes. |
--------------------------+------------------------------+
I must here leave the _rationale_ of the process for the present, and
proceed with the next operation.
Our emulsion being cold, I add to it, for every 6 ounces of mixed
emulsion, 1 ounce of a saturated cold solution of potassium bichromate;
then, gently swirling the mixture round, a few drops of a dilute (1 to
8) solution of hydrochloric acid, and place it on one side for a minute
or two.
When hydrochloric acid is added to bichromate of potash, chromic acid is
liberated. Now, chromic acid has the property of precipitating gelatine,
so that what I hope to have done is to have precipitated the gelatine in
this emulsion, and which will carry down the silver bromide as well. You
see here I can pour off the supernatant liquid clear, leaving our silver
and gelatine as a clot at the bottom of the vessel.
Another action of chromic acid is, that it destroys the action of light
on silver bromide, so that up to this point operations can be carried on
in broad daylight.
The precipitated emulsion is now taken into the dark room and washed
until the wash water shows no trace of color; if there be a large
quantity, this is best done on a fine muslin filter; if a small
quantity, by decantation.
Having been thoroughly washed, I dissolve the pellicle in water by
immersing the beaker containing it in the water bath. I then add the
remaining gelatine, and make up the whole with 3 ounces of alcohol and
water to 30 ounces for the quantities given. I pass the emulsion through
a funnel containing a pellet of cotton wool in order to filter it, and
it is ready for coating the plates.
To coat a plate, I place it on this small block of leveled wood, and
pour on down a glass rod a small quantity of the emulsion, and by means
of the rod held horizontally, spread it over the plate. I then transfer
the plate to this leveled slab of plate glass, in order that the
emulsion on it may set. As soon as set, it is placed in the drying box.
This process, as here described, does not give plates of the highest
degree of sensitiveness, to attain which a further operation is
necessary; they are, however, of exceedingly good quality, and very
suitable for landscape work.--_Photo. News_.
* * * * *
PICTURES ON GLASS.
The invention of M. E. Godard, of Paris, has for its object the
reproduction of images and drawings, by means of vitrifiable colors on
glass, wood, stone, on canvas or paper prepared for oil-painting and on
other substances having polished surfaces, e. g., earthenware, copper,
etc. The original drawings or images should be well executed, and drawn
on white, or preferably bluish paper, similar to paper used for ordinary
drawings. In the patterns for glass painting, by this process, the place
to be occupied is marked by the lead, before cutting the glass to suit
the various shades which compose the color of a panel, as is usually
done in this kind of work; the operation changes only when the glass
cutter hands these sheets over to the man who undertakes the painting.
The sheets of glass are cut according to the lines of the drawing, and
after being well cleaned, they are placed on the paper on the places for
which they have been cut out. If the window to be stained is of large
size and consists of several panels, only one panel is proceeded with
at a time. The glass is laid on the reverse side of the paper (the side
opposite to the drawing), the latter having been made transparent by
saturating it with petroleum. This operation also serves to fix the
outlines of the drawing more distinctly, and to give more vigor to the
dark tone of the paper. When the paper is thus prepared, and the sheets
of glass each in its place, they are coated by means of a brush with
a sensitizing solution on the side which comes into contact with the
paper. This coating should be as thin and as uniform as possible on
the surface of the glass. For more perfectly equalizing the coating, a
second brush is used.
The sensitizing solution which serves to produce the verifiable image is
prepared as follows: Bichromate of ammonia is dissolved in water till
the latter is saturated; five grammes of powdered dextrin or glucose are
then dissolved in 100 grammes of water; to either of these solutions
is added 10 per cent. of the solution of bichromate, and the mixture
filtered.
The coating of the glass takes place immediately afterward in a dark
room; the coated sheets are then subjected to a heat of 50 deg. or 60 deg. C.
(120 deg. to 140 deg. Fahr.) in a small hot chamber, where they are laid one
after the other on a wire grating situated 35 centimeters above the
bottom. Care should be taken not to introduce the glass under treatment
into the hot chamber before the required degree of heat has been
obtained. A few seconds are sufficient to dry each sheet, and the wire
grating should be large enough to allow of the dried glass being laid in
rows, on one side where the heat is less intense. For the reproduction
of the pictures or images a photographic copying frame of the size of
the original is used. A stained glass window being for greater security
generally divided into different panels, the size of one panel is seldom
more than one square meter. If the picture to be reproduced should be
larger in size than any available copying frame, the prepared glass
sheets are laid between two large sheets of plate-glass, and part after
part is proceeded with, by sliding the original between the two sheets.
A photographic copying frame, however, is always preferable, as it
presses the glass sheets better against the original. The original
drawing is laid fiat on the glass of the frame. The lines where the lead
is to connect the respective sheets of glass are marked on the drawing
with blue or red pencil. The prepared sheets of glass are then placed
one after the other on the original in their respective places, so that
the coated side comes in contact with the original. The frame is then
closed. It should be borne in mind that the latter operations must be
performed in the dark room. The closed frame is now exposed to light. If
the operations are performed outdoors, the frame is laid flat, so that
the light falls directly on it; if indoors, the frame is placed inclined
behind a window, so that it may receive the light in front. The time
necessary for exposing the frame depends upon the light and the
temperature; for instance, if the weather is fine and cloudless and the
temperature from 16 deg. to 18 deg. C. (60 deg. to 64 deg. Fahr.), it will require from
12 to 15 minutes.
It will be observed that the time of exposure also depends on the
thickness of the paper used for the original. If, however, the weather
is dark, it requires from 30 to 50 minutes for the exposure. It will be
observed that if the temperature is above 25 deg. C. (about 80 deg. Fahr.), the
sheets of glass should be kept very cool and be less dried; otherwise,
when exposed the sheets are instantly metallized, and the reproduction
cannot take place. The same inconvenience takes place if the temperature
is beneath 5 deg. C. (41 deg. Fahr.). In this case the sheets should be kept
warm, and care should be taken not to expose the frame to the open air,
but always behind a glass window at a temperature of from 14 deg. to 18 deg.
C. (about 60 deg. Fahr.). The time necessary for the exposure can be
ascertained by taking out one of the many pieces of glass, applying to
the sensitive surface a vitrifiable color, and observing whether the
color adheres well. If the color adheres but slightly to the dark, shady
portions of the image, the exposure has been too long, and the process
must be recommenced; if, on the contrary, the color adheres too well,
the exposure has not been sufficient, the frames must be closed again,
and the exposure continued. When the frame has been sufficiently
exposed, it is taken into the dark room, the sensitized pieces of glass
laid on a plate of glass or marble with the sensitive surface turned
upward, and the previously prepared vitrifiable color strewed over it by
means of a few light strokes of a brush. This powder does not adhere to
the parts of the picture fully exposed to light, but adheres only to the
more or less shady portions of the picture. This operation develops
on the glass the image as it is on the paper. Thirty to 40 grammes
of nitric acid are added to 1,000 grammes of wood-spirit, such as is
generally used in photography, and the prepared pieces of glass are
dipped into the bath, leaving them afterward to dry. If the bath becomes
of a yellowish color, it must be renewed. This bath has for its object
to remove the coating of bichromate, so as to allow the color to adhere
to the glass, from which it has been separated by the layer of glucose
and bichromate, which would prevent the vitrification. The bath has also
for its object to render the light parts of the picture perfectly
pure and capable of being easily retouched or painted by hand. The
application of variously colored enamels and the heating are then
effected as in ordinary glass painting. The same process may be applied
to marble, wood, stone, lava, canvas prepared for oil painting,
earthenware, pure or enameled iron. The result is the same in all cases,
and the process is the same as with glass, with the difference only that
the above named materials are not dipped into the bath, but the liquid
is poured over the objects after the latter have been placed in an
inclined position.
* * * * *
PREPARATION OF HYDROGEN SULPHIDE FROM COAL-GAS.
By I. TAYLOR, B.A., Science Master at Christ College, Brecon.
Hydrogen sulphide may be prepared very easily, and sufficiently pure
for ordinary analytical purposes, by passing coal-gas through boiling
sulphur. Coal-gas contains 40 to 50 per cent, of hydrogen, nearly the
whole of which may, by means of a suitable arrangement, be converted
into sulphureted hydrogen. The other constituents of coal-gas--methane,
carbon monoxide, olefines, etc.--are not affected by passing through
boiling sulphur, and for ordinary laboratory work their removal is quite
unnecessary, as they do not in any way interfere with the precipitation
of metallic sulphides.
[Illustration: PREPARATION OF HYDROGEN SULPHIDE FROM COAL-GAS.]
A convenient apparatus for the preparation of hydrogen sulphide from
coal-gas, such as we have at present in use in the Christ College
laboratory, consists of a retort, R, in which sulphur is placed.
Through the tubulure of the retort there passes a bent glass-tube, T E,
perforated near the closed end, F, with a number of small holes. (The
perforations are easily made by piercing the partially softened glass
with a white-hot steel needle; an ordinary crotchet needle, the hook
having been removed and the end sharpened, answers the purpose very
well.) The end, T, of the glass tube is connected by caoutchouc tubing
with the coal-gas supply, the perforated end dipping into the sulphur.
The neck of the retort, inclined slightly upward to allow the condensed
sulpur, as it remelts, to flow back, is connected with awash bottle, B,
to which is attached the flask, F, containing the solution through which
it is required to pass the hydrogen sulphide; F is connected with an
aspirator, A.
About one pound of sulphur having been introduced into the retort and
heated to the boiling-point, the tap of the aspirator is turned on and
a current of coal-gas drawn through the boiling sulphur; the hydrogen
sulphide formed is washed by the water contained in B, passes on into
F, and finally into the aspirator. The speed of the current may be
regulated by the tap, and as the aspirator itself acts as a receptacle
for excess of gas, very little as a rule escapes into the room, and
consequently unpleasant smells are avoided.
This method of preparing sulphureted hydrogen will, I think, be found
useful in the laboratory. It is cleanly, much cheaper than the ordinary
method, and very convenient. During laboratory work, a burner is placed
under the retort and the sulphur kept hot, so that its temperature may
be quickly raised to the boiling-point when the gas is required. From
time to time it is necessary to replenish the retort with sulphur and to
remove the condensed portions from the neck.--_Chem. News_.
* * * * *
"SETTING" OF GYPSUM.--This setting is the result of two distinct, though
simultaneous, phenomena. On the one hand, portions of anhydrous calcium
sulphate, when moistened with water, dissolve as they are hydrated,
forming a supersaturated solution. On the other hand, this same solution
deposits crystals of the hydrated sulphate, gradually augment in bulk,
and unite together.--_H. Le Chatellier_.
* * * * *
[Continued from SUPPLEMENT No. 383, page 6118.]
MALARIA.
By JAMES H. SALISBURY, A.M., M.D.
PRIZE ESSAY OF THE ALBANY MEDICAL COLLEGE ALUMNI ASSOCIATION, FEB.,
1882.
VII.
I have made careful microscopic examinations of the blood in several
cases of Panama fever I have treated, and find in all severe cases many
of the colorless corpuscles filled more or less with spores of ague
vegetation and the serum quite full of the same spores (see Fig. N,
Plate VIII.).
Mr. John Thomas. Panama fever. Vegetation in blood and colorless
corpuscles. (Fig N, Plate VIII.) Vegetation, spores of, in the colorless
corpuscles of the blood. Spores in serum of blood adhering to fibrin
filaments.
Mr. Thomas has charge of the bridge building on the Tehuantepec
Railroad. Went there about one year ago. Was taken down with the fever
last October. Returned home in February last, all broken down. Put him
under treatment March 15, 1882. Gained rapidly (after washing him out
with hot water, and getting his urine clear and bowels open every day)
on two grains of quinia every day, two hours, till sixteen doses were
taken. After an interval of seven days, repeated the quinia, and so on.
This fever prevails on all the low lands, as soon as the fresh soil
is exposed to the drying rays of the sun. The vegetation grows on the
drying soil, and the spores rise in the night air, and fall after
sunrise. All who are exposed to the night air, which is loaded with the
spores, suffer with the disease. The natives of the country suffer about
as badly as foreigners. Nearly half of the workmen die of the disease.
The fever is a congestive intermittent of a severe type.
Henry Thoman. Leucocythaemia. Spleen 11 inches in diameter, two white
globules to one red. German. Thirty-six years of age. Weight, 180
pounds. Colorless corpuscles very large and varying much in size, as
seen at N. Corpuscles filled--many of them--with the spores of ague
vegetation. Also spores swimming in serum.
This man has been a gardener back of Hoboken on ague lands, and has had
ague for two years preceding this disease.
I will now introduce a communication made to me by a medical gentleman
who has followed somewhat my researches for many years, and has taken
great pains of time and expense to see if my researches are correct.
REPORT ON THE CAUSE OF AGUE.--BY DR. EPHRAIM CUTTER, TO THE WRITER
At your request I give the evidence on which I base my opinion that your
plan in relation to ague is true.
From my very start into the medical profession, I had a natural intense
interest in the causes of disease, which was also fostered by my father,
the late Dr. Cutter, who honored his profession nearly forty years.
Hence, I read your paper on ague with enthusiasm, and wrote to you for
some of the plants of which you spoke. You sent me six boxes containing
soil, which you said was full of the gemiasmas. You gave some drawings,
so that I should know the plants when I saw them, and directed me to
moisten the soil with water and expose to air and sunlight. In the
course of a few days I was to proceed to collect. I faithfully followed
the instructions, but without any success. I could detect no plants
whatever,
This result would have settled the case ordinarily, and I would have
said that you were mistaken, as the material submitted by yourself
failed as evidence. But I thought that there was too much internal
evidence of the truth of your story, and having been for many years
an observer in natural history, I had learned that it is often very
difficult for one to acquire the art of properly making examinations,
even though the procedures are of the simplest description. So I
distrusted, not you, but myself, and hence, you may remember, I forsook
all and fled many hundred miles to you from my home with the boxes you
had sent me. In three minutes after my arrival you showed me how to
collect the plants in abundance from the very soil in the boxes that had
traveled so far backward and forward, from the very specimens on which I
had failed to do so.
The trouble was with me--that I went too deep with my needle. You showed
me it was simply necessary to remove the slightest possible amount on
the point of a cambric needle; deposit this in a drop of clean water on
a slide cover with, a covering glass and put it under your elegant 1/5
inch objective, and there were the gemiasmas just as you had described.
I have always felt humbled by this teaching, and I at the time rejoiced
that instead of denouncing you as a cheat and fraud (as some did at that
time), I did not do anything as to the formation of an opinion until I
had known more and more accurately about the subject.
I found all the varieties of the palmellae you described in the boxes,
and I kept them for several years and demonstrated them as I had
opportunity. You also showed me on this visit the following experiments
that I regarded as crucial:
1st. I saw you scrape from the skin of an ague patient sweat and
epithelium with the spores and the full grown plants of the Gemiasma
verdans.
2d. I saw you take the sputa of a ague patient and demonstrate the
spores and sporangia of the Gemiasma verdans.
3d. I saw you take the urine of a female patient suffering from ague
(though from motives of delicacy I did not see the urine voided--still I
believe that she did pass the urine, as I did not think it necessary to
insult the patient), and you demonstrated to me beautiful specimens of
Gemiasma rubra. You said it was not common to find the full development
in the urine of such cases, but only in the urine of the old severe
cases. This was a mild case.
4th. I saw you take the blood from the forearm of an ague patient, and
under the microscope I saw you demonstrate the gemiasma, white and
bleached in the blood. You said that the coloring matter did not develop
in the blood, that it was a difficult task to demonstrate the plants in
the blood, that it required usually a long and careful search of hours
sometimes, and at other times the plants would be obtained at once.
When I had fully comprehended the significance of the experiments I was
filled with joy, and like the converts in apostolic times I desired to
go about and promulgate the news to the profession. I did so in many
places, notably in New York city, where I satisfactorily demonstrated
the plants to many eminent physicians at my room at the Fifth Avenue
Hotel; also before a medical society where more than one hundred persons
were present. I did all that I could, but such was the preoccupation of
the medical gentlemen that a respectful hearing was all I got. This is
not to be wondered at, as it was a subject, now, after the lapse of
nearly a decade and a half, quite unstudied and unknown. After this I
studied the plants as I had opportunity, and in 1877 made a special
journey to Long Island, N.Y., for the purpose of studying the plants in
their natural habitat, when they were in a state of maturity. I have
also examined moist soils in localities where ague is occasionally
known, with other localities where it prevails during the warm months.
Below I give the results, which from convenience I divide into two
parts: 1st. Studies of the ague plants in their natural habitat. 2d.
Studies of the ague plants in their unnatural habitat (parasitic). I
think one should know the first before attempting the second.
_First_--Studies to find in their natural habitat the palmellae described
as the Gemiasma rubra, Gemiasma verdans, Gemiasma plumba, Gemiasma alba,
Protuberans lamella.
_Second_--_Outfit_.--Glass slides, covers, needles, toothpicks, bottle
of water, white paper and handkerchief, portable microscope with a good
Tolles one inch eyepiece, and one-quarter inch objective.
Wherever there was found on low, marshy soil a white incrustation like
dried salt, a very minute portion was removed by needle or toothpick,
deposited on a slide, moistened with a drop of water, rubbed up with a
needle or toothpick into a uniformly diffused cloud in and through the
water. The cover was put on, and the excess of water removed by touching
with a handkerchief the edge of the cover. Then the capillary attraction
held the cover in place, as is well known. The handkerchief or white
paper was spread on the ground at my feet, and the observation conducted
at once after the collection and on the very habitat. It is possible
thus to conduct observations with the microscope besides in boats on
ponds or sea, and adding a good kerosene light in bed or bunk or on
lounge.
August 11, 1877.--Excursion to College Point, Flushing, Long Island:
Observation 1. 1:50 P.M. Sun excessively hot. Gathered some of the white
incrustation on sand in a marsh west of Long Island Railroad depot.
Found some Gemiasma verdans, G. rubra; the latter were dry and not good
specimens, but the field swarmed with the automobile spores. The full
developed plant is termed sporangia, and seeds are called spores.
Observation 2. Another specimen from same locality, not good; that is,
forms were seen but they were not decisive and characteristic.
Observation 3. Earth from Wallabout, near Naval Hospital, Brooklyn, Rich
in spores (A) with automobile protoplasmic motions, (B) Gemiasma rubra,
(C) G. verdans, very beautiful indeed. Plants very abundant.
Observation 4. Walking up the track east of L. I. R.R. depot, I took an
incrustation near creek; not much found but dirt and moving spores.
Observation 5. Seated on long marsh grass I scraped carefully from the
stalks near the roots of the grass where the plants were protected from
the action of the sunlight and wind. Found a great abundance of mature
Gemiasma verdans very beautiful in appearance.
_Notes_.--The time of my visit was most unfavorable. The best time is
when the morning has just dawned and the dew is on the grass. One then
can find an abundance, while after the sun is up and the air is hot the
plants disappear; probably burst and scatter the spores in billions,
which, as night comes on and passes, develop into the mature plants,
when they may be found in vast numbers. It would seem from this that the
life epoch of a gemiasma is one day under such circumstances, but I have
known them to be present for weeks under a cover on a slide, when the
slide was surrounded with a bandage wet with water, or kept in a culture
box. The plants may be cultivated any time in a glass with a water
joint. A, Goblet inverted over a saucer; B, filled with water; C, D,
specimen of earth with ague plants.
Observation 6. Some Gemiasma verdaus; good specimens, but scanty.
Innumerable mobile spores. Dried.
Observation 7. Red dust on gray soil. Innumerable mobile spores. Dried
red sporangia of G. rubra.
Observation 8. White incrustation. Innumerable mobile spores. No plants.
Observation 9. White incrustation. Many minute algae, but two sporangia
of a pale pink color; another variety of color of gemiasma. Innumerable
mobile spores.
Observation 10. Gemiasma verdans and G. rubra in small quantities.
Innumerable mobile spores.
Observation 11. Specimen taken from under the shade of short marsh
grass. Gemiasma exceedingly rich and beautiful. Innumerable mobile
spores.
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