172 
ON EMPLASTRUM PLUMBI. 
The ashes remaining after lixiviation were mixed with 
dilute muriatic acid and left to stand for a short time. The 
solution being separated by filtration, produced a precipi- 
tate with binoxalate of potassa consisting of oxalate of 
lime. « 
By the experiments detailed in this essay, it has been 
shown that the root contains the following principles : 
Vegetable Albumen , Gum, Starch, Gallic acid, Fixed 
Oil, traces of Volatile Oil, a Peculiar Resinous Principle, 
soluble in alcohol and ether, and another soluble in alco- 
hol only. Both possessed the active properties of the 
root, but the former is most active. The ashes were found 
to contain potassa, lime, and a chloride. 
To these may be added as constituents of the root, lignin 
and extractive matter. 
ART. LIT.— ON EMPLASTRUM PLUMBt. 
By N. Spencer Thomas. 
[An Inaugural Essay.) 
1st. One pint of olive oil was treated by boiling with 
two ounces of hydrated sesquioxide of iron, a portion of 
water being added as in the preparation of lead plaster; 
the mixture was kept at the temperature of 212° over a 
steady fire (fresh portions of water being added as the 
evaporation proceeded) for the space of three hours, at 
which time no change had taken place, except in colour, 
which was somewhat lighter than before the operation was 
commenced, probably from a change of oxidation, and not 
from any union of the oily acids with the oxide of iron. 
