[ 6 39 J

perfumes are said to be frequently mixed with it. Theauthor observes that the Chinese have inks of differentgoodness and price; that the most essential difference pro-ceeds from the quality of the lamp-black; and that thebest lamp-black is the foot of oil, which is burnt inlamps, in apartments fitted up for this purpose. TheChinese, according to his account, imagine the differencesin the foot of different oils, &c. to be much greater thanthe experiments related in page 342 give room to believethey are.

Page 369. Black varnish for metals.

The workmen frequently employ for this purpose, as Iam informed, a mixture of lamp-black with the feum-mings, &c. of different oil paints:, the mixture is appliedwith a pencil, and the piece afterwards baked in an oven,with a heat somewhat greater than is used for the papiermache. Naplea yellow, a superfluous ingredient in theblack varnish, is the basis of the dark brown which we feeon some iron snuff-boxes, this pigment changing to abrown in baking with the varnish.

Page 596. Separation of the alcali ofsea fait .

1. Purification of sea fait ..

Pure marine salt is a combination of the mineral alca-line salt with marine acid : but all the common, sorts ofthis fait have a mixture of one or more saline matters of adifferent composition, their basis, instead of an alcalinefait, being an earth; which earth is generally the samewith that failed magnesia, though sometimes, perhaps, itmay be of the calcareous kind.

ic. These .