48 
DR. JOHN STENHOUSE ON THE NITROGENATED PRINCIPLES OF 
observation. Now coal is universally admitted to be exclusively of vegetable origin, 
and to consist of the remains of a variety of vegetables, which, after having undergone 
putrefactive fermentation, and been subjected to probably enormous compression, 
have lain for countless ages in the bowels of the earth. 
When reflecting therefore on the probable sources of the organic bases in coal, it 
has for some time past appeared to me highly probable that they are not derived from 
the woody fibre and other non-nitrogenated vegetable matters from which the coal has 
been principally formed ; but that these bases are exclusively derived from the highly 
nitrogenated principles, previously enumerated, contained in the plants of the coal- 
fields. From the energetic agencies to which coal has been subjected, it seemed 
probable that much of the nitrogen originally present in the vegetables from which 
it has been formed must have been dissipated, and consequently the amount of bases 
now obtainable from coal proportionally diminished. It appeared therefore only 
reasonable to expect, that by acting on the nitrogenated principles of recent vege- 
tables, the same organic bases as those contained in coal, or at any rate a series of 
analogous bases, would be obtained in proportionally greater abundance. In the 
sequel it will appear that this latter expectation has not been altogether disappointed. 
It is extremely difficult to obtain vegetable albumen, fibrine, or caseine in consider- 
able quantity in a state of purity. And though several chemists have bestowed 
much attention on the subject, as none of these principles are crystallizable, it is very 
doubtful if any of them have yet been obtained in a state of absolute purity. Instead 
therefore of endeavouring to purify these principles, I contented myself with select- 
ing those portions of our commonest plants, usually their seeds, which contain them 
in the greatest abundance. 
The first substance on which I operated was the seeds of the Phaseolus communis, 
or common horse-bean. This bean contains about 20*8 per cent, of caseine and 
]’35 per cent, of albumen, amounting in all to a little more than 22 per cent, nitro- 
genous matter. The beans were destructively distilled in cast-iron cylinders, about 
three feet high and eight inches in diameter. The products of the distillation were 
collected by means of a large condensing Liebig’s apparatus, kept carefully cool. 
A great deal of combustible but non-condensable gas was evolved. It had a very 
disagreeable foetid odour. The liquid which passed into the receiver was strongly 
alkaline, so much so as to require about a third of its bulk of muriatic acid of ordi- 
nary strength to neutralize it. It closely resembled the products of the distillation 
of bones, flesh and other animal matters, being very complex, and comprising, among 
other substances, acetone, wood-spirit, acetic acid, empyreumatic oils, tar, a great 
deal of ammonia, and several organic bases. The crude produce of the distillation 
was then treated with a considerable excess of muriatic acid, and the clear liquid, 
after subsidence, was poured off from the tar and other empyreumatic matters which 
had fallen to the bottom of the vessel. The tarry residue was also repeatedly 
agitated with small quantities of water, so long as any bases appeared to be dis- 
