Nitrate of silver 1 drachm. Acetic acid 2 drachms. Distilled water 7 ounces. Dissolve the nitrate of silver in the distilled water, and then add the acetic acid. _Fixing Solution._ Hyposulphite of soda 2 ounces. Water 1 pint--dissolve. _Varnish._ The varnish best adapted for this purpose is that supplied by Home & Thornthwaite, and termed negative varnish.[H] [Footnote H: In this country, Humphrey's Collodion Gilding is the article in almost universal use.] _Cleaning the Plate._ The plates must be cleaned in the usual way, merely premising that extra care must be observed to remove every impurity, as cleanliness in photography is an absolute necessity. In order to hold large plates whilst being cleaned, the "screw plate-holder" is exceedingly useful. This is made in three sizes, and adapts itself to all sized plates. The small size is useful for plates up to 7 inches by 6. The second size is for plates up to 10 inches by 8. And the third size for plates up to 14 inches by 10. _Coating with Iodized Collodion._ The plate having been thoroughly cleaned, and received its final polish by the use of a prepared chamois leather, is coated with negative collodion, which has been iodized at least twelve hours, and allowed to settle. _Exciting the Collodion Film._[I] [Footnote I: This and subsequent operations (except exposure in the camera) must be performed in a dark room.] After the ether has evaporated, and the surface of the collodion appears set, the plate must be laid, collodion side upwards, on a glass dipper, and plunged with _one downward movement_ into a bath filled to within an inch of the top with collodion bath solution, made as described at page 190, which must be carefully filtered through filtering paper before being used. After the plate has been allowed to remain in the bath one minute, it is lifted out three or four times, in order to facilitate the removal of the oily appearance the plate now presents. When the surface appears wetted uniformly, on being drawn out of the solution the plate is removed from the dipper, and the excess of solution drained off, and is then placed collodion side upwards, on a fixing stand, and distilled or filtered rain water poured over the surface, so as to remove as much as possible of the bath solution from the surface. The plate is now removed from the fixing stand; the back well washed with water, and then placed nearly upright on blotting paper, with the face against a wall for _one minute_ to drain. _Coating with Albumen._