202 wa Paris. 
powder of the mineral itself, and used as a substitute. —Tech. 
Repository, 15. 
48. Ink.*—The bark of the chestnut (Fagus castanea) is 
said to contain twice as much tan as that of the oak, and gives 
with sulphate of iron a. beautifully black ink. The colour 
which this tan produces is less liable to change by the sun and 
rain, than that produced by sumac.—Precess, Monatsblatt, 
Jani 1822. | 
49. Watchmakers’ Oil.—The best oil for diminishing 
friction in delicate machinery, is that which is entirely de- 
prived of every species of acid, and of mucilage, and is ca- 
pable of enduring intense cold without congealing. The oil, 
in fact, should be pure elaine, without any trace of stearine. 
Now it is no difficult thing to extract the elaine from all 
fixed oils, and even those from seeds, by the process of Chev- 
reul, which consists in treating the oil with seven or eight times 
its weight of alcohol, almost boiling hot, decanting the liquid, 
and exposing itto cold. The stearine will then separate in 
the form of a cristalline precipitate. The alcoholic solution 
is then to be evaporated to the fifth of its volume. What is 
left is the elaine, which ought to be colourless, insipid, almost 
without smell, without any action on the infusion of tourn- 
sol, and having the consistence of white olive oil, and with 
difficulty coagulable.— Bulletin Univ. Feb, 1824. 
50. Panis —There are in this city 520 Watchmakers, who 
employ about 2056 workmen, and produce annually 80,000 
gold watches, 40,000 silver watches, and 15,000 clocks, the 
whole worth about 19,765,000 francs. 
nthe same city there are thirty tanneries, in which 300 
workmen prepare every year at a medium, 45,000 ox-hides, 
4,v00 cow-hbides, 8,000 horse-hides, 60,000 calf-skins, and 
employ in this operation, 11 millions of pounds of tan, 97,000 
pounds of alum, 500 pouuds of tallow, and the same quantity 
of salt. The produce of this branch of commerce is esti- 
mated at 3.726.000 frances. The number of houses sold annu- 
ally in Paris is about 4,200. 
Of printing establishments there are 80, occupying 3000 
workmen, moving 600 presses, and employing yearly 280,800 
reams of paper, which yield a receipt of 8,750,000 francs. 
* See Mr. Sheldon’s notice, Vol. 1. pa. 312 &c. of this Journal. 
——— eT 
