48 TRANS. OF THE ACAD. OF SCIENCE. 
in the water. If this water be again used in the saponification of 
a new portion of fat, the solution becomes more concentrated, so 
thas. y the evaporation of 100 buckets of such water, we wou 
obtain from 12 to 14 gallons of impure a glycerin; 
it will re to evaporate these 100 buckets 15 bushels of coal. — 
Inthe watery solution of glycerin, there is contained much - 
caustic lime, which remains in the concentrated article. It has 
been proposed by some French chemists, to remove this by the 
aid of sulphuric acid; but no glycerin treated Re) this very defec- 
tive and tedious method is. entirely free from _ 
The following method will be found to be by far more simple and 
more effective:—Into the somewhat concentrated solution of gly- 
cerin, throw pieces of carb. ammonia sufficient to thrown down 
as a carbonate all the caustic lime, stirring constantly while the 
vy Soe proceeds; keep the solution boiling at a temperature 
of between 140° to 150° C; this is effected by adding a little wa- 
ter when n the walation becomes so concentrated as to raise the boil- 
ing point higher;. in the course of an hour or two, all the the caus- 
tic ammonia, as well as the excess of carbonate added, passes off. 
The method of clarification discovered by Wilson consists m 
ating, “gece gee by the application of over- : 
He so obtained, is entirel 
