PREPARATION OF SIMPLE PLASTER. 
case. But no one, as far as I know, has carried the examina? 
tion further. It appears sufficient to state, that it may be 
possible to obtain the simple plaster in a different way from 
the ordinary method, without seeking to ascertain if any 
advantage would accrue, and if it were not practicable to in- 
troduce into practice a ready and easy preparation, in the 
place of the tedious and disagreeable manipulation which is in 
use at this time. 
Now it appears to me that a note which would have the 
effect of attracting attention to this subject, would not be en- 
tirely destitute of interest, and it is under this belief that I 
risk the publication of the results of my experiments. 
Having dissolved a pound of white Marseilles soap in a 
sufficient quantity of warm water, I added to the solution 8 
ounces of acetate of lead. As soon as the mixture occurred 
decomposition took place and the plaster floated upon the sur- 
face of the liquid, which then became completely transparent. 
This liquid was not rendered cloudy by sub-acetate of lead, 
and sulphuretted hydrogen produced but a little abundant 
precipitate. Having separated it, I washed the plaster, in 
order to rid it of the soluble salts which it might contain, 
after which I mixed it, and formed it into rolls.* 
Thus obtained, it possessed an extreme whiteness, not to 
be obtained in the ordinary way. It softens perfectly in 
warm water, and mixes with great facility. And it does not 
become coloured as it grows older, which circumstance I at- 
tribute to the complete saturation of the acids of the fat; very 
different in this respect from the other, which always becomes 
more or less coloured. 
It had only one defect. Some hours after its preparation, 
it assumed a consistence almost too firm, which, however, it 
but slightly communicated to the compounds into which it 
w^as introduced. 
It has been said that the simple plaster, although obtained 
*This mode of proceeding in the formation of this plaster, was sug- 
gested by Mr. Durand, of Philadelphia, in a note upon Ceratum Sapoiiis, 
published in Vol. VIII., No. I. of this .lournal. - Ed. 
