LECTURE ON CHEMISTRY. 
67 
last division of his subject,—more pleasing and more important to 
those whom he addressed, for it was coming home to their business 
and bosoms,—the application of the principles of chemistry to 
medicine. “ The remedies,” said he, that were first employed 
in the treatment of disease were mostly simples, or, if chemical 
compounds were occasionally administered, they were not such as 
were prepared by art, but found native. Thus, carbonate of soda 
was abundant on the margin of lakes, and nitrate of potash efflo¬ 
resced on the soil. 
“ The medicinal effects of numerous vegetables were early recog¬ 
nized ; but, in order to derive advantage from them, it was neces¬ 
sary to administer them in very considerable bulk. One of the 
great advantages obtained by a knowledge of chemistry was the 
method of extracting the active principle, and discarding the bulky 
mass,—at all times inconvenient, and occasionally preventing the 
full development of the power of the chief agent. The application 
of opium, of the vomic nut, and of various other agents, has been 
thus rendered more simple, and manageable, and effective. 
“By the aid of chemistry we obtain other and more potent agents 
from the mineral kingdom. The two useful preparations of mercury 
—calomel and corrosive sublimate—are apt elucidations of the union 
of a metal with an elementary substance. In the compounds of 
antimony, and copper, and zinc, we have farther illustration of our 
subject; and in the numerous class of substances, most safe and 
useful, termed salts, we have the most important exemplification 
of the triumph of chemistry. There are several of these which 
Nature never gave to us, at least in a sufficient quantity to be 
available for the use of man. 
“ To chemistry we likewise owe the power of increasing the po¬ 
tency of our remedies by the judicious combination of various 
substances; and, on the other hand, when the nature of the disease 
requires it, we can, by our knowledge of chemical laws, reduce the 
most powerful of them to the precise degree of strength which we 
require. 
“It is to the neglect of the study of chemistry that the introduc¬ 
tion of many gross and barbarous compounds, by some who call 
themselves veterinary surgeons, is to be traced. Wherever a mul¬ 
titude of agents are jumbled together, as in the greater part of the 
old recipes, and too many of the modern ones, the result often is 
the neutralization of some of the most important principles, or the 
formation of a new agent of deleterious influence. The solution of 
the acetate of lead and the sulphate of zinc has been employed 
as a collyrium, but they who use it forget the decomposition 
which takes place on admixture; in like manner, the tincture of 
opium, to increase the sedative power of the lead: but what is 
the consequence 1 The active principle of the opium is precipitated 
