62 
SELECTED ARTICLES. 
number which is certainly not the maximum of the effect pro- 
duced by this agent. 
M. Thilorier adds that this example of the solidification of 
a gas, is the more striking and extraordinary, from its having 
taken place with a gas which requires a great mechanical com- 
pression to enable it to assume a liquid state, and which in- 
stantly resumes its natural form as soon as the pressure is re- 
moved. Journ. de Pharm. 
ART. XII.— NEW RESEARCHES ON OPIUM AND ITS PRIN- 
CIPLES. By J. Pelletier. 
I. 
I hesitated for a long time, before I determined to present 
this memoir, thinking that another treatise on opium would 
be considered as a work of supererrogation. At the same 
time, I felt satisfied that many particulars, especially of the 
chemical history of this drug, were still involved in obscurity, 
and required elucidation. In a former paper, I made known 
a new principle, narceine; still more recently, I announced 
that another principle also existed in it, which I named para- 
morphine; but these two substances required further investi- 
gation as respected their chemical and physical properties. 
The analysis of an opium obtained in France, by incisions 
made in the capsules of the poppy, presented some peculiari- 
ties worthy of notice; as for instance, the absence of narcotine 
and its replacement by an additional portion of morphia; the 
discovery of a substance which is only accidentally to be met 
with in opium, and which although wholly different from mor- 
phia, might be confounded with this salt. My being in pos- 
session of some facts with regard to morphia of great impor- 
tance in legal medicine; and, finally, my desire of rendering 
