MANUFACTURE OF ACETATE OF SODA. 
149 
plate, where it becomes solid, and is afterwards broken up and 
dissolved in water. This solution when dosed with sulphuric 
acid, yields pure acetic acid. Sometimes the sulphate of soda is 
dissolved in the crude acid, and the chalk or lime subsequently 
added, a portion of fuel required for evaporation is thus saved. 
The most economical plan, however, is that of saturating the acid 
liquor with sulphuret of sodium, as recommended by Turner, the 
only objection to its employment arising from the sulphuretted 
hydrogen evolved in the process, which has been known to affect 
individuals living upwards of two miles from the works where the 
process was in use. The double decomposition process above de- 
scribed, is by no means a satisfactory one. The sulphate of lime 
resulting from the decomposition carries some of the salt away 
with it by direct combination; it also robs us indirectly, inasmuch as 
we cannot wash it so as to take away all the acetate of soda, on 
account of the fuel required to evaporate the water used. In de- 
composing the acetate of lime by sulphate of soda, there is more 
delicacy required than workmen find convenient ; the consequence 
is that there generally exists in the acetate of soda solution, either 
acetate of lime or sulphate of soda ; the latter is removed by boil- 
ing out, but the former runs the crystals, as the workmen call it, 
that is, prevents crystallization. This happens not unfrequently. 
Not more than one ton of acetate of soda is usually obtained 
from a ton of acetate of lime, and oftentimes a much less quantity. 
In some manufactories of acetate of soda, the salt is not made 
to undergo igneous fusion ; but it is purified from all extraneous 
matters by repeated crystallizations and filtrations through animal 
charcoal, previously well washed with dilute hydrochloric acid. 
Care should be taken that the solution of the fused salt has not a 
greater specific gravity than 1.116, otherwise the carbonaceous 
matter with which it is mixed will not settle; the solution should 
then be allowed to settle for twelve hours, the clear liquor poured 
off, evaporated to 1.250, and put to crystallize. 
Mitscherlich recommends that the solution of acetate of lime 
employed should be of specific gravity 1.116; and that the solu- 
tion of acetate of soda be evaporated to 1.230, or 1.240, and then 
put aside to crystallize. Another process is that of neutralizing 
the acid liquor with soda-ash ; this is no doubt the most conveni- 
ent process, but not the most economical. — Pharmaceutical Jour* 
ml, October 1, 1850. 
13* 
