nitrate of silver, and 2 drops of hydrochloric acid per ounce. Put this
in your stock solution bottle, and keep it in a dark place for
twenty-four hours. When first put in, it will be milky; when taken out,
it will be creamy; and it will be well to shake it once or twice in the
twenty-four hours.

At the end of this time you can make your two dozen plates in about an
hour. Proceed as follows: Have two porcelain dishes large enough to hold
four or six of your plates; into one put sufficient clean water to nearly
fill it, into the other put 30 ounces of clear, flat, _not acid,_ bitter
beer, in which you have dissolved 30 grains of pyrogallic acid. Pour this
through a filter into the dish, and avoid bubbles. If allowed to stand an
hour, any beer will be flat enough; if the beer be at all brisk, it will
be difficult to avoid small bubbles on the plate. At all events, let your
preservative stand while you filter your emulsion. This must be done
through perfectly clean cotton-wool into a perfectly clean collodion
bottle; give the emulsion a good shaking, and when all bubbles have
subsided, pour it into the funnel, and it will go through in five
minutes. The filtered emulsion will be found to be a soft, smooth, creamy
fluid, flowing easily and equally over the plates. Coat with it six
plates in succession, and place each, as you coat it, into the water. By
the time the sixth is in, the first will be ready to come out. Take it
out, see that all greasiness is gone, and place it in the preservative,
going on till all the plates are so treated.

A very handy way of drying is to have a flat tin box of the usual hot
plate description, which fill with hot water, then screw on the cap; on
this flat tin box place the plates to dry, which they will do rapidly;
when dry, store away in your plate box, and you will have a supply of
really excellent dry collodion plates.