ON GLYCERIN. 
127 
of it. The consistence of the latter was rather more brittle ; 
it had a shorter fracture and smoother, with no appearance of 
moisture, and retained its whiteness longer by keeping. A 
plaster was spread of each, and neither was thought to be 
superior to the other in regard to its adhesive properties. And 
when we consider that the lead plaster of commerce is never 
entirely without glycerin, or with the full quantity formed 
during the decomposition of the oil, it may safely be stated, 
that little or no deterioration, in the quality of lead plaster, 
takes place from the abstraction of the quantity of glycerin, 
which is obtained from it, and reserved for separate purposes. 
The costliness of this article, prevents it from general appli- 
cation in pharmacy ; but I think, there are a few cases in 
which its employment would be advantageous. For instance 
in the pills of sulphate of quinine, which are directed in cases 
where it is important that disease should be speedily arrested, 
it is necessary that they should be quickly soluble in the sto- 
mach. Those made from gum and syrup, have been known 
to pass through the system untouched ; and should any objec- 
tion be had to the tonic extracts which have sometimes been 
used, glycerin forms an excellent substitute. A trial was made, 
using different quantities of glycerin, to the same amount of the 
sulphate, and it was found, that those made according to the U. 
S. Pharmacopoeia, in 24 hours became hard and brittle, while 
in the cases where glycerin was used, the entire amount of 
syrup being replaced by it, the mass retained the proper con- 
sistence. In the other cases the quality decreased in propor- 
tion to the amount of glycerin, in direct ratio. Glycerin near- 
ly without water was used, being much better than the diluted 
article seen in commerce ; one drop of the former being equal 
in weight to two of the latter, and containing about twice as 
much anhydrous glycerin. There are other cases in which its 
use would be proper, but I merely propose this as applying to 
an important and valuable preparation. 
As the various uses and peculiar properties of this substance 
gradually develope themselves, endeavors will be made to dis- 
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