Scientific American Supplement, No. 358, November 11, 1882

V >> Various >> Scientific American Supplement, No. 358, November 11, 1882

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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.

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