
DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 253 
I have thus then established the existence, among the products of destructive 
distillation, of ammonia, and the first four members of the series of bases homo- 
logous with it. I have every reason, however, to believe that the series does not 
end with petinine, for the fraction boiling about 200° yields a platinum salt in fine 
scales, and having all the characters of the salts of the same series of bases, and 
in all probability contains valeramine. I am not without hope also of obtaining 
caprylamine; but this I expect will be the last of the series, for when we reach 
the temperature of about 240°, the character of the bases changes, and we enter 
upon an entirely different. series. 
In the separation of the bases boiling above 240°, I have encountered very great 
difficulties. After the trial of many different processes, such as converting them 
into salts, exposing them to cold, partial saturation, and every other plan which 
appeared likely to answer, I have been compelled to return to fractionated distil- 
lation, as the method most likely to answer the end I had in view. But even with 
this process the difficulties are great, and I have been by no means so successful in 
obtaining fixed boiling points as I was when operating on a smaller scale in my 
former preparations. I subjected the whole of the oils boiling above 212° to a sys- 
tematic course of fractionation, each fraction being distilled alone, and the product 
collected in a fresh series of bottles, and the receivers changed at every ten de- 
grees. In the earlier rectifications each fraction spread itself over a very large num- 
ber of degrees, and shewed little tendency towards concentration to fixed points. 
The distillations were repeated no less than fourteen times, but even after all this 
the indications of boiling points were extremely indistinct.. Sometimes in one dis- 
tillation certain fractions appeared larger than others, but their pre-eminence disap- 
peared again in succeeding rectifications. Still a certain improvement was manifest, 
some of the fractions being confined more nearly to the range of degrees within 
which they had boiled at the previous rectification. It was obvious, from the whole 
phenomena of the distillation, that the separation of the different bases was going 
on, although with extreme slowness; and at this point I endeavoured, by the 
examination of the platinum salts obtained at different temperatures, to deter- 
mine the constitution of the bases which these fractions contained ; and as I knew 
from previous experiment, that the quantity boiling between 270° and 280° con- 
sisted of picoline, I had from this fact indications of the temperatures at which 
bases were likely to be found, and I have thus been enabled to determine the 
existence of two substances belonging to the same homologous series with that 
substance. 
Pyridine. 
_ The first of these bases, to which I give the name of pyridine, occurs in the 
fraction boiling about 240°. This fraction has an odour precisely similar to that of 
picoline, but more powerful and pungent. It is perfectly transparent and colour- 
