166 
Book III. 
METHOD OF OBTAINING 
carbon. The processes described'in a former part of 
this Work furnish it as pure as it can be procured. 
7. Tin may be obtained pure by solution in strong 
nitric acid ; the white oxide of tin is formed, which is 
insoluble. Let it be digested first with muriatic acid, 
and afterwards with aqua regia. Mix the oxide thus 
purified with its weight of pitch and a little borax, and 
melt it in a crucible. 
8. Lead may be dissolved in nitric acid, and precipi 
tated by sulphat of soda ; wash the precipitate, and melt 
it in a crucible with 24 times its weight of black flux. 
9. Nickel may be obtäined pure from kupfer nickel, 
by roasting the ore previously mixed with charcoal; 
dissolving it in nitric acid, evaporating the solution to 
dryness, redissolving it in water, precipitating by pot 
ass, and boiling the precipitate with potass. The pre 
cipitate is then to be eduleorated, dissolved in acetous 
acid, the solution evaporated to dryness, redissolved in 
water, and precipitated by ammonia in excess, which 
redissolves the oxides of cobalt and nickel. By eva 
porating this solution the cobalt is precipitated, and the 
solution becomes blue. This last solution, evaporated 
to dryness, gives pure oxide of nickel. Form this ox 
ide into a paste with oil, mix it with two or three parts 
of black flux, and put it into a crucible, covering it up 
with borax and common salt. Heat the crucible vio 
lently for an hour and a half in a smith's forge. A but 
ton of pure nickel is obtained. 
10. Zinc may be dissolved in sulphuric acid, and a 
plate of zinc allowed to remain for a considerable time 
in the solution, It is then to be filtered, and the zinc 
to be precipitated with soda. The precipitate, edulco 
rated and dried, is to be mixed with half its weight of