can be detected by the
experienced operator. Thus muriatic acid is added for its chlorine,
which can generally be detected by the impression produced, being of a
light, soft, mellow tone, and in most cases presenting a brilliant
black to that colored drapery. Those who wish to experiment with
agents for accelerating substances, should first study to well
understand their peculiar nature and properties; as well, also, to
endeavor to find out what will be the probable changes they undergo in
combination as an accelerator. This should be done before making the
experiments. From the foregoing it will be seen that numerous
compounds are formed from the same basis, and, consequently, it would
be a waste of time and a useless appropriation to devote more of our
space than is necessary to give the principal and most reliable
combination.

In America, the words "Quick" and "Quick Stuff," are more generally
used for and instead of the more proper names, "Sensitives," or
"Accelerators," etc. As it has by use become common, I frequently use
it in this work.

Liquid Accelerator, No. 1.--This mixture was used by me in 1849, and is
given as it appeared in my "System of Photography," published at the
above date:

Take pure rain or distilled water, one quart, filter through paper into
a ground stopper bottle, and add, for warm weather, one and a half
ounce chloride of iodine; or for cold, one ounce; then add one ounce
bromine, and shake well. Now with care not to allow the vapor to
escape, add drop by drop, thirty drops of aqua ammonia, shaking well at
each drop. Care must be taken not to add more at a time, as it evokes
too much heat. This mixed, in equal proportions with John Roach's
quick, forms an excellent chemical combination. For this purpose, take
one and a half ounce of each, to which add ten ounces water, for warm
weather, or from six to seven for cold. Pour the whole into a large
box, and it will work from two to four months. I am now using (1849)
one charged as above which has been in constant use for three months,
and works uniformly well. The above is right for half or full size
boxes, but half of it would be sufficient for a quarter size box.

Coat to the first shade of rose over iodine, change to a deep rosy red
over quick, and black about one tenth the first.

I would not now recommend the addition of "John Roach's quick," as I
believe equally good results can be produced without it. This liquid
is