The Houston daily post. [volume] (Houston, Tex.) 1886-1903, 1900-05-25
yrr,.-pEvELoPINe.
BY FELIX RAYlMER-

Now ghat the negative has been made
and we have our darkroom ready, tne
next thing to do win be to deleyop the
image. 1t wGl be found on examination
that the film 10 all appearances is Just tne
sams Chat It was when first placed IN the
plage -holder, so that 1t becomes neces-
snry to do something that will bring OUT
the image on the plate as we saw 1t ON
the ground glass when We made the ex-
posure. To do this II is necessary 20 COM
Dine certain chemicals and apply them 10
the plate. This is called developing,
and the combination OF chemicals 10 called
the Developer" The developer can be
made up in quantities In what is caiied
stock solutions" BY this 1t Is meant
that the chemicals are mixed TO a certain
strength and then each time There Is an
exposure TO be developed certain quaint
ties are taken from the stock solutions
for that particular exposure, che remain
der of the stock solution" 6eing tightly
corked Cor duGure use. For the amateur,
making only a few exposures month
for pleasure, it would possibly be more
economical and less troublesome to use
some one of the many ready prepared
developers. any OF which viii give good
| results when properly used. These ready
prepared solutions may be obtained from
any reliable stockhouse and directions
4 for their use accompany each preparation.
Believing, however that the greatest BEN
eft and best work can he obtained by mix
4 ing our own developer 1T Is with that
branch of the developing we will now deal.
Doubtless what is known as the 'pyro-
gallo acid" developer Is the most popular
OF all the developers now in use, therefore
I that Mll he mentioned first. The first
thing to do is to make up stock solu-
iion" of the various chemicals used.
This is done in the following way: Take
three BOTTLES, each holding about one
quart. Number them l and and g. II
number l a solution of Carbonate OF
potassium" should he made to test" 40
degrees. This is done by means of a lit
tie instrument known as hydrometer,
obtained from some stock dealer at
cost OF about so cents This hydrometer
Is hollow glass tube with bar arranged
something like a thermometer which drops
into the tube. This method for mixing
chemicals is far more satisfactory than by
weight as the chemicals are then ALWAYS
made at exactly the same strength, where
as II made by weight they may vary sew
eral degrees. from the fact that certain
chemicals when exposed TO air lose some
Of their strength, while others Will in
crease in strength. Now, to get 40
degree solution fill bottle No. l about two
thirds full OF water and add carbonate OF
potassium "a little at time, shaking after
each addition until dissolved and then
pouring the glass tube of the hydrometer
fun and testing until the desired strength
is obtained In bottle No. a solution OF
"sulphbte OF sodes' should be made and
should test 80 degrees. This test is made
in the same way as the carbonate" test.
In bottle No. put "a ounces of water,
in which dissolve 10 grains of oxalic acid.
After this is dissolved add one ounce OF
pyrogallc acid.
Now eveythig is ready for developing
the plate. The same light may be used
that was used for holding the plate hold
ers 1t win be supposed that the plate
is about by inches in size. or course
tray of that size must be used. To de-
velop plate by inches it will take at
least four onuces of developer to flow
the plate properly, so start in by taking
one-half ouncs of solution No |, onehalf
ounce OF solution No. 2 and one-hak ounce
of solution No 3. Add to this four ounces
of water. In mixing the developers only
the very purest water obtainable should pe
used. Melted ice gives a good, pure water.
Now, to get the best results in developing
1t is necessary to understand Just what
each chemical does so that II we ind
sometime wrong 1t may be remedied, To
begin with. II a plate should be examined
under a powerful microscope 1t wou4H be
seen that the finn is deposited on the plate
in the form OF small sacks, or globules.
In each Of these little sacks is tiny par
ticle Ct bromide of silver. When the plate
/ is exposed, the light affects any OF this
silver that may be exposed to it, and by
the use CT developers this affected silver
is developed up so &bat We get what IS
called The negative" The action OF the
carbonate OF potassium on the plate is 20
/ break these little sacks that have been
acted upon by the light. The pyrogaillc
acid is called the 'Tblackening agent" 1t
is this that causes that part of the film
that mas been acted upon by light 10 turn
dark. The sulphite OF soda is known as
the Clearing solution" This controls
the col Or in dhe negative. by varying the
strength OF these chemicals in che devel-
oper 10 he used on the different expos
ures different effects can be chained
FOR Instance. suppose it is known that
the plate is underlined, more of the Cal :
Donate of potassium should be added,
/