DESCH AMPS ON POMMADES. 
261 
Heat in a tinned vessel until all the water is driven off, 
then pass through linen, and stir until it becomes cool. 
After having proved that these ointments, which I have 
called Benzoated and Populinated grease, did hot after 
several years offer any change in odor, I sought by means 
of proper re-agents to discover if this observation was con- 
firmed, and to discern the difference between the prepared 
grease and ordinary fat bodies. I knew that red oxide of 
mercury was changed by the common fatty substances. I 
was aware of the readiness with which fatty bodies acidified 
when either the acetate or subacetate of lead was mixed 
with them. I perceived that the Iodide of Potassium might 
serve in the promptest manner to discover rancidity or 
acidity in fatty bodies, and I arrived at this conclusion by 
the aid of experiments, useless to detail here since the re- 
sults are exhibited in the formulas which I propose — that 
the fatty bodies the least alterable are the benzoated and 
populinated greases, and immediately after follows butter 
melted with caution. 
That the populinated grease, by reason of the coloring 
matter it takes from the buds, becomes orange colored by 
the agency of alkalines contained therein, or substances 
having similar action. That this change is limited to the 
coloring matter is proved by subacetate of lead, which after 
a very long time merely colors it without changing its nor- 
mal odor. 
The following Ointments may be prepared: — 
OINTMENT OF IODIDE OF POTASSIUM. 
Iodide of potassium, - 4.00 grms. 
Water, 4 00 " 
Benzoated grease, ... 30.00 " 
This ointment may likewise be prepared with populinated 
grease or with butter. Six months witnesses no change in 
this preparation. 
