The celebrated " Armenian " cement, so called formerly used by Turkish and Oriental jewelers generally, for setting precious stones, " facing diamonds," rubies, etc., is made as follows:

Mastic gum........ 10 parts

Isinglass (fish glue) . 20 parts

Gum ammoniac .... 5 parts Alcohol absolute.... 60 parts

Alcohol, 50 per cent.. 35 parts

Water............. 100 parts

Dissolve the mastic in the absolute alcohol; dissolve, by the aid of gentle heat, on the water bath, the isinglass in the water, and add 10 parts of the dilute alcohol. Now dissolve the ammoniacum in the residue of the dilute alcohol. Add the first solution to the second, mix thoroughly by agitation and then add the solution of gum ammoniac and stir well in. Finally put on the water bath, and keeping at a moderate heat, evaporate the whole down to 175 parts.