ON GLYCERINE. 
O 
formed — lead-plaister , — and glycerine will be found to be re- 
tained by the water. 
This aqueous solution is to be freed from any lead it contains 
by means of a stream of sulphuretted hydrogen passed through 
it ; then digested with animal charcoal, and afterwards fil- 
tered and evaporated to the consistency of syrup by expo- 
sure in vacuo over oil of vitrol. As thus procured, it is 
not unfrequently still contaminated with a little lead, unless 
the greatest care be exercised. 
But by far the larger amount of this principle is procured 
during the manufacture of soaps ; the theory of the saponifi- 
cation of fats and oils being now rendered extremely simple, 
which is as follows : When oils or fats are boiled in a solu- 
tion of soda or potassa, the stearic, margaric, and oleic acids 
leave the glycerine and combine with the soda or potassa, 
forming stearate, margarate, and oleate of soda or potash, as 
may be ; the former constituting the harder soaps, the latter, 
soft soap ; so that these again are true salts. The glycerine 
being thus left in combination with the water, which pre- 
viously held the alkaline base, soda or potash, in solution, the 
liquor is to be rendered neutral by the addition of dilute sul- 
phuric acid, then filtered and evaporated to a syrupy con- 
sistence, and from this the glycerine is to be extracted by 
alcohol and evaporation. 
Glycerine, like most other newly discovered substances, at 
first, while it awakened some curiosity, was not turned to 
any useful account, and tons of it were thrown away yearly. 
The following are some of the uses to which it has been of 
late applied ; which are extracted from a paper read by Mr. 
G. F. Wilson, at the meeting of the British Association, held 
at Glasgow, in 1855 : 
“ The first suggestion of a use for glycerine, of which we can trace dates is 
in the beginning of 1844, when Mr. Thomas De la Rue, being engaged on some 
experiments requiring the use of syrupy substances, procured some glycerine 
from Mr. Warrington, of Apothecaries’ Hall, some of* which he applied to a 
burn and an irritation of the skin. The experience thus obtained of its pro- 
perties of soothing and keeping moist, led to its introduction, through Mr. 
Startin, into the Hospital for Skin Diseases, where it soon came into ex- 
tensive use. 
“ In 1 846, Mr. Warrington took out a patent for the use of glycerine as an 
agent in preserving animal and vegetable substances, and tried many ex- 
periments on preserving meat. He informs me that part of a neck of 
mutton, preserved in glycerine for several months, when cooked by Soyer, 
was partaken of by a gentleman with great satisfaction. 
“ Mr. Warrington, I believe, first applied glycerine in mounting objects for 
the microscope, for which it has since proved so successful. 
“In the Lancet of June, 1849, Mr. Thomas Wakley published the results 
of a year’s experience, in a long and very interesting paper on the use of 
