232 VINEGAR, CIDER, AND FRUIT-WINES. 



The specific gravity of charcoal depends on the carbonizing 

 temperature. The specific gravity of charcoal from bird-cherry 

 carbonized at 590 F. is 1.42, at 810 F. 1.7.1, at 1873 F. 1.84, 

 at 2732 F. 1.87, and at the fusing point of platinum 2.0. 



The power of charcoal of conducting heat and electricity also 

 increases to a remarkable extent with the increase in the carboni- 

 zing temperature. 



The inflammability of charcoal is the greater the lower the 

 temperature at which it was prepared. 



Charcoal possesses the property of absorbing gases and of 

 taking up liquid and solid bodies from fluids, for instance, fusel 

 oil, coloring substances, and alkaloids. Lead salts, for instance, 

 lead acetate and nitrate, are decomposed on boiling with charcoal, 

 the latter absorbing the lead oxide and liberating a corresponding 

 quantity of acid. 



Charcoal also absorbs aqueous vapor from the air, and the 

 more the lower the temperature at which it was formed ; the 

 quantity varies from 4 to 20 per cent. Hence the charcoal ex- 

 posed to the air contains only about f of its weight of carbon. 



Wood- Vinegar. 



After standing for several days in the previously-mentioned 

 reservoir, the greater portions of the wood-vinegar and tar sepa- 

 rate and form two layers, less often three. In the latter case the 

 upper layer, which amounts to but little and may be entirely 

 wanting, consists of specifically light volatile oils holding tar and 

 acetic acid in solution. The second layer forms the principal 

 mass and is the actual wood-vinegar. The lowest layer is tar, 

 rich in specifically heavy volatile oils, especially phenol (creasote), 

 containing, however, also acetic acid ; it is of a yellow-brown to 

 black color, of a syrupy consistency, and specific gravity 1.07 to 



The layers are drawn off separately by means of stop-cocks 

 placed at different heights on the reservoir. 



Wood-vinegar is a strongly acid fluid, generally perfectly clear, 

 of a brown-yellow to red-brown color, and a strong odor (par- 



