MEMOIR OF THE LATE DR. HENRY. 123 
But although his original efforts in chemistry 
were mainly directed to the gases, he was by 
no means a stranger to other provinces of ex- 
perimental research. His comparative analyses 
_ of many varieties of British and Foreign Salt, 
were important in refuting the prejudices, then 
widely prevalent, of the superiority of the latter 
for certain economical purposes. His Essay on 
the Materiality of Heat, published in the Me- 
moirs of this learned body, is written with force 
and perspicuity, though in modern times the 
tide of doctrine undoubtedly sets in the opposite 
direction. His critical memoir on the theories 
of galvanic decomposition has even lately been 
noticed with praise by Berzelius in his Jahrs- 
bericht, as among the first to assert that view, 
which in his judgment is still most deserving of 
adoption. But of the soundness and extent of 
Dr. Henry’s acquaintance with general chemis- 
try his “Elements” furnish undoubted proof. 
This work, which in 1829 had passed through 
eleven editions, has always held a high place in 
public estimation, as a clear and faithful record 
of the details of chemistry, and as conveying 
in its general chapters, a distinct and compre- 
hensive survey of the leading doctrines and 
higher philosophy of the science. 
