Clasp the glass firmly in the vice, and pour or _spurt_ upon it a little alcohol and rotten stone, previously formed into a paste, and then, with a piece of cotton flannel, the same as used in the daguerreotype, rub the glass until it is perfectly cleansed from all foreign substances, which will soon be known by experience. The rotten stone paste should not be allowed to dry while rubbing, as it is more liable to scratch the glass. I use another small bottle containing clear alcohol, which I spurt upon the glass, to obviate the drying. When the glass has been sufficiently cleaned, it should, while wet, be put in a vessel of water for future rinsing. Clean, as before, as many plates of glass as may be required, and when enough are ready, rinse them off in the water, and then in a quantity of clean water, or a running current, give them a second thorough rinsing, and set them aside to drain. A convenient method of doing this, is to drive two nails horizontally into the wall or partition, a sufficient distance apart (say about 2-1/2 inches) for the glass to rest on: the upper corner of the glass should be placed against the wall, and the extreme lower diagonal corner left hanging between the nails--which will probably be found the best position for draining yet suggested. After drying, they may be put into a box for safe and clean keeping. Particular caution is necessary to avoid handling the glass during the operation. I never take the glass between my fingers, so that they come in contact with _both sides_ of it, except at one particular corner, as at Figs. A and B. A quantity of glass prepared as above, may be kept on hand for use two or three days, and when wanted they should be again put into the vice[C] and cleaned, first with cotton flannel wet with alcohol, and then with dry flannel; and then, at a temperature slightly above that of the surrounding atmosphere, except in cases where the thermometer stands above 70°, it is ready for the brush,[D] which should be carefully applied to each surface, to free it from all particles of dust, and then it is ready for the film of collodion. [Footnote C: The vice should be thoroughly cleansed, and no particles of rotten stone, or other matter, be allowed to come in contact with the glass, as it might adhere to the edges and wash off into the silvering bath, and ultimately cause specks. Always remember that cleanliness is an indispensable requisite in order to produce a good picture.] [Footnote D: One of the most desirable articles I have found for this purpose is the wide (3 inch) flat camel's-hair brush often called a blender.] [Illustration: Fig. A. Fig. B.]