114 REMARKS ON OLEORESINOUS ETHEREAL EXTRACTS. 
substances. Thus the analysis of defiant gas gives as its 
formula CH ; but from its density and other circumstances 
it should be C 2 H 2 or C 4 H 4 . The formula deduced from the 
analysis of sugar is CHO, but it decomposes into alcohol and 
carbonic acid, and, therefore, either C 2 H 3 0-f C0 2 =C 3 H 3 3 
ought to be the formula, or C 6 H 6 6 or C 12 Hi 2 12 , which last, 
indeed, is most generally received. A formula may also be 
doubled or trebled, if viewed as a bibasic or tribasic acid. 
Therefore, after determining the simplest formula for an 
organic body, its more rational formula is determined by 
the specific gravity of its vapour, by its mode of combining 
with bases or acids, or by its metamorphoses." 
Our limits forbid us from making further extracts. Those 
which we have given will we hope induce our readers to 
possess themselves of the book which should be the vade 
mecum of the chemical student. 
ART. XXVI. — REMARKS ON OLEO-RESINOUS ETHEREAL EX- 
TRACTS, THEIR PREPARATION, AND THE ADVANTAGES 
THEY OFFER TO THE MEDICAL PRACTITIONER. 
By William Procter, Jr. 
Quite a number of drugs owe their medicinal activity 
and value to the existence among their constituents of a 
resin and volatile oil, and these frequently exist in such 
quantity as to yield fluid, or semi-fluid extracts when the 
ethereal tinctures of the drugs are evaporated. Cubebs 
Black Pepper, Cardamoms, Ginger, Worm-seed and Pella- 
tory are among these, In volume IS, page 167 of this 
Journal, the writer published an essay on " the Ethereal Ex- 
tract of Cubebs," a preparation which has since met, to a 
