MANUFACTURE OF ACETIC ACID. 
263 
Acetate of 
silver . . 
i f\<~i on ft 
St 
copper . . 
. . 84.868 
(( 
nickel . 
. . 44.731 
t( 
iron . . 
. . 27.236 
ic 
lead . . 
. . 3.045 
a 
zinc . . 
. . 2.258 
(C 
magnanese 
. . 1.285 
The crystallized acetate of copper is the salt most usually em- 
ployed for this purpose — twenty pounds of the powdered acetate 
are placed in an earthen retort of the capacity of about two gal- 
lons, previously luted and exposed to the action of the fire ; the 
elongated neck of the retort is connected with a tubulated receiver, 
and this with a second and third, the last of which is furnished 
with a Welter's safety tube, dipping into water. The heat must 
at first be carefully applied, then gradually increased, and the 
operation regulated by the deveiopement of the gaseous products, 
which must not be too slow, or too fast. The receivers must be 
kept cool. When on increasing the heat it is found that no more 
vapors are given off, the fire must be put out, and the apparatus 
left to cool. The acid thus obtained has a greenish color, its spe- 
cific gravity is 1.061. From 20 pounds of acetate of copper rather 
more than 9j pounds of rough acid are obtained. The residum in 
the retort consists of 6| pounds of copper in a metallic state, mix- 
ed with a small quantity of charcoal. The crude acid thus obtained 
is next placed in a glass retort of the capacity of about 1J gallon 
to which is adapted a tubulated receiver, and the retort is heated by 
means of a sand-bath. The first portions which come over are 
very weak, and the product should be kept separate until it comes 
over of a density of 1.072 ; the whole of the remaining product is 
now collected together, and the distillation continued to dryness. 
The acid obtained shows a specific gravity of 1.088. The weaker 
products are redistilled, and the stronger portions mixed with the 
former. The 9| pounds of crude acid furnish in this way six 
pounds of pure acid, specific gravity 1.085, three pounds at speci- 
fic gravity 1.042, and half a pound specific gravity 1.023. The 
small portion of acetone which comes over with the acid imparts 
an agreeable aroma to it, and the addition of camphor and essen- 
tial oils constitutes the aromatic vinegar of commerce. 
Manufacture of Acetic Acid by the Decomposition of Acetate of 
