(1) Ether, 500 gr.; sandarac, 30 gr.; mastic, 30 gr. Dissolve, then add benzine in small quantities, till the varnish, spread on a piece of glass, gives it the aspect of roughened glass. The varnish is used cold. To have a homogeneous layer, pour over that already formed some oil of petroleum, let it evaporate a little, then rub in all directions with cambric cloth till all is quite dry. With ink or lead pencil, lines can be produced on this surface as fine as may be desired. Thus a drawing may be prepared in a few minutes and immediately projected. (Crova.)
(2) The glass is to be first gently heated at a spirit lamp or gas flame, till steam ceases to be deposited on it, up to 112° or 140° F. (44° to 60° C). Then a particular varnish should be poured upon it, as is done in photographic operations with collodion. This varnish is composed of 51 dwt. alcohol, 61 gr. mastic in drops, and 122 gr. pounce. The resins are dissolved by being heated in a hot water bath, the whole being in a flask corked and fastened. The solution is .afterwards filtered. The varnish is very hard, and becomes brilliant and completely trans-parent. If it is poured on the cold glass, it becomes opaque and absorbs ink. Drawings may be executed upon it with common or Indian ink. Then a thin layer of gum is put upon it by dipping the glass in a very diluted solution of gum or any other non - alcoholic coating. This process might be advantageously employed instead of labels on bottles in laboratories, and for making figures on glass, and perhaps for tracing drawings, which might thus be reproduced by photography. (Terquem.)
(3) A mixture of flour, ammonia hydrate,and hydrochloric acid, thickened with gum acacia, forms an ink by which, with a pen, letters or ornaments may be traced on glass, where they will become permanent.
(4) Faber makes pencils for writing upon glass, porcelain, metal, etc, as follows:- Black: 10 parts lampblack, 40 white wax, 10 - of tallow. White: 40 white - lead, 20 wax, 10 tallow. Blue : 10 Berlin blue, 20 wax, 10 tallow. Dark Blue : 15 Berlin blue, 5 gum - arabic, 10 tallow. Yellow; 10 chrome - yellow, 20 wax, 10 tallow.