Destructive Distillation of Animal Substances. 1 75 



not they were actually identical, but on too small a scale to 

 admit of a definite solution of the question. 



These observations, coupled with the doubts which had 

 been expressed by some chemists, and more especially by 

 Reichenbach, as to the existence of the bases described by 

 Unverdorben, induced me to take up the whole subject of the 

 products of the destructive distillation of animal substances, 

 which has not yet been investigated in a manner suited to the 

 requirements of modern chemistry. In fact, Unverdorben is 

 the only person who has examined them at all; and his ex- 

 periments, contained in the eighth and eleventh volumes of 

 PoggendorfPs Annalen, constitute the whole amount of our 

 knowledge on the subject; and his observations, though valu- 

 able, and containing perhaps as much as could easily be de- 

 termined at the time he wrote, are crude and imperfect, when 

 we come to compare them with those which the present state 

 of the science demands. Since his time, the methods of in- 

 vestigation in organic chemistry have undergone an entire 

 change : the simplifications of the process of organic analysis 

 had not then been made, or at least had not come into daily 

 use as the auxiliary of investigation ; and Unverdorben, who 

 belonged to the old school, and contented himself with the 

 observation of reactions only, was necessarily led, as I shall 

 afterwards more particularly show, to confound together sub- 

 stances, the reactions of which approximate so closely that it 

 is impossible, or at least very difficult, to distinguish them by 

 such means alone. The errors, however, lay with the method, 

 and not with the observer; for Unverdor ben's experiments, 

 so far as they go, I have found to be correct in the main, 

 notwithstanding their having been called in question by Reich- 

 enbach, whose numerous researches on the kindred subject of 

 the products of the destructive distillation of vegetable sub- 

 stances gave weight to his opinion, and have indeed been the 

 principal cause of the doubts expressed by others on the subject. 



The investigation of these products has occupied me pretty 

 continuously since the publication of the paper before alluded 

 to ; and my researches have now extended themselves over a 

 large part of the subject, although, from its branching off into 

 so many subdivisions, and embracing the consideration of so 

 large a number of substances belonging to almost every class 

 of organic compounds, some time must still elapse before it is 

 complete in all its parts. It is my intention, therefore, as tne 

 subject naturally divides itself into several sections, to take up 

 the consideration of these in a succession of papers, of which 

 the present is the first, and in which I propose to consider the 

 general properties of the crude product employed in my ex- 



