35^ Prout on the ultimate composition 
however unremitting, a sufficiency for the establishment of 
general laws. Professional duties still further limited my 
exertions, and at length obliged me to relinquish chemistry 
in general, and confine my attention solely to the chemistry 
of organized substances; a subject that has occupied the 
greater portion of my leisure hours for the last ten or twelve 
years. 
Organic chemistry is confessedly one of the most difficult 
departments of the science; and though much has been 
done, and more attempted on the subject, it is yet in a very 
imperfect and unsatisfactory state; and it must be frankly 
admitted that Physiology and Pathology have derived less 
advantage from this most promising and really powerful of 
the auxiliary sciences, than might have been expected. To 
explain this perhaps would not be difficult; but as the ex¬ 
planation would be misplaced here, I shall merely observe, 
that dissatisfied with the old modes of inquiry, I determined 
to attempt a different one, and keeping in view the notions I 
had originally formed respecting chemical combinations, pro¬ 
posed to myself to investigate the modes in which the three 
or four elementary substances entering into the composition 
of organized bodies are associated, so as to constitute the 
infinite variety occurring in nature. 
With these views my first object was to determine the 
exact composition of the most simple and best defined organic 
compounds, such as sugar, and the vegetable acids, a point 
that had been several times before attempted, but, as it ap¬ 
peared to me, without complete success. About the same 
time also albumen and other animal products, as urea, lithic 
acid, &c. were examined with similar views. The subject 
