PREPARATION OP SIMPLE PLASTER. 
127 
materials being furnished, the one by a crystallized salt, the 
other by an article of commerce, always constant in its com- 
position, there will be no necessity of testing them. 2d. 
Because the duration of the operation will never exceed the 
time necessary for the solution of the soap. Finally, because 
the chances of loss are less, since the plaster, from remaining 
but a few minutes upon the fire, can neither boil over or be 
burned, as sometimes happens, when, in pursuing the ordi- 
nary method, it is forgotten to add water. 
Preparation. 
Marseilles soap, in slices, Ibj. 
Warm water Ibij. 
Dissolve, and add to the solution 
Crystallized acetate of lead §viij. 
Stir the mixture slowly, with a wooden spatula, until the 
liquid becomes transparent. Decant, re-wash the plaster, and, 
after having worked, form into rolls. Each roll should 
weigh one pound. 
If it be desired to increase the quantity of the plaster, add 
two ounces of fatty acids to the pound. I have obtained these 
fatty acids by decomposing] four ounces of the same' soap by 
four drachms of sulphuric acid, diluted with three or four 
ounces of water. 
From the plaster thus prepared, all the compound plasters 
may be formed, according to the ordinary formulae. 
But the very slight diflference which exists between the 
compounds prepared from the plaster without addition, and 
that to which the fatty acids have been added, induces me to 
suppose, that the same result would be obtained, by increasing 
the amount of the wax or oil entering into these preparations.* 
Journal de Pharmacie. 
* The Committee of the Society of Pharmacy of Paris, to whom was 
referred the above essay, composed of MM. Chevalier, Lecanu, and 
Felix Boudet, reported favourably of the process recommended. 
