•202 Paris. 



powder of the mineral itself, and used as a substitute. — Ttch. 

 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. Monatsblait. 



Jan. 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 it to 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 Paris —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. 



In the same city there are thirty tanneries^ in which 300 

 workmen prepare every year at a medium, 45,000 ox-hides, 

 4,\i>00 cow-hides, 8,000 horse-hides, 60,000 calf-skins, and 

 employ in this operation, 1 1 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 francs The number of houses sold annu- 

 ally in Paris is about 4,200, 



O^ printing estahlishments 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. feheldoa's notice, Vol. 1. pa. 312 &c. of this Journal. 



