Files which have become clogged with tin or lead are cleaned by dipping for a few seconds into concentrated nitric acid. To remove iron filings from the file cuts, a bath of blue vitriol is employed. After the files have been rinsed in water they are likewise dipped in nitric acid. File-ridges closed up by zinc are cleaned by immersing the files in diluted sulphuric acid. Such as have become filled with copper or brass are also treated with nitric acid, but here the process has to be repeated several times. The files should always be rinsed in water after the treatment, brushed with a stiff brush, and dried in sawdust or by pouring alcohol over them, and letting it burn off on the file.

Scale Pan Cleaner

About the quickest cleaner for brass scale pans is a solution of potassium bichromate in dilute sulphuric acid, using about 1 part of chromate, in powder, to 3 parts of acid and 6 parts of water. In this imbibe a cloth wrapped around a stick (to protect the hands), and with it rub the pans. Do this at tap or hydrant, so that no time is lost in placing the pan in running water after having rubbed it with the acid solution. For pans not very badly soiled rubbing with ammonia water and rinsing is sufficient.

Tarnish on Electro-Plate Goods

This tarnish can be removed by dipping the article for from 1 to 15 minutes— that is, until the tarnish shall have been removed—in a pickle of the following composition: Rain water 2 gallons and potassium cyanide 0.5 pound. Dissolve together, and fill into a stone jug or jar, and close tightly. The article, after having been immersed, must be taken out and thoroughly rinsed in several waters, then dried with fine, clean sawdust. Tarnish on jewelry can be speedily removed by this process; but if the cyanide is not completely removed it will corrode the goods.