ON THE CONSTITUENTS OF LACTUCARIUM. 
61 
gave no precipitates with oxide of mercury or silver; oxide 
of mercury dissolved in it without being reduced. The acid 
is evidently acetic acid. The oil did not dissolve entirely 
in alcohol, but readily in ether. Lactucerine cannot be 
saponified by caustic potash, but melts on evaporation to 
a brown mass, and is decomposed. The hydrate of sul- 
phuric acid dissolves lactucarium immediately with a brown 
colour; nitric acid likewise dissolves it, and yields on eva- 
poration a yellow residue soluble in ammonia. It gave on 
analysis — 
Carbon, 76.202 77.286 77.090 40 = 76.650 
Hydrogen, 10.654 10.832 10.902 34 10.719 
Oxygen, 13.144 11.882 12.008 5 12.631 
Two other experiments yielded results corresponding to the 
formula C*^ H^^ 0*, while Lenoir found for lactucone 
C oH^^O^. It appears therefore that lactceurine prepared 
from fresh lactucarium may be converted into lactucone by 
the elimination of 1-2 equivs. water. Lactucone and lac- 
tucerine are distinguished from caoutchouc, a name which 
has sometimes been applied to them by containing oxygen. 
On examining a lactucerine which consisted of microscopic 
crystals, the author obtained exactly the same composition 
for it as for the amorphous; both agreed with Lenoir's for- 
mula, having been prepared from old lactucarium. 
Inorder to determine the other constituents of lactucarium 
the author let the milk sap ooze out of the plant into distil- 
led water. In a few moments it separated into a bright 
yellow clear solution and into white floating flakes ; the 
portion insoluble in alcohol was digested several times with 
ether, and this then removed by distillation. It left a waxy 
body, which melted at a gentle heat, and produced a per- 
manent stain of fat upon paper. The aqueous solution of 
lactucarium when fresh is perfectly neutral, but becomes 
sour on boiling. The liquid separated from the coagulated 
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