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portion of a grayish-black substance was produced, which wa3 highly 

 inflammable, was easily melted, and was readily dissolved in cold 

 alcohol ; from which, like the resins, it might be precipitated by 

 water. 



From coagulated albumen, and from prepared muscular fibre, no- 

 thing but coal could be obtained. 



In the above experiments there appeared to be a certain period of 

 the process when the production of the tanning substance arrived at 

 its maximum ; after which a gradual diminution, and at length a 

 total destruction of it, took place, and it became mere coal. 



Some experiments are now related, made with nitric acid, on the 

 elastic bitumen, and on several kinds of coal. The result was, that 

 from elastic bitumen, common pit-coal, Cannel-coal, and asphaltum, 

 there was obtained, not only the tanning substance, but also another 

 substance, which possessed properties intermediate between those of 

 resin and those of vegetable extractive matter ; but this substance 

 might, by digestion in nitric acid, be converted into the tanning sub- 

 stance. From Kilkenny-coal, and from two other kinds of coal, one 

 from Wales, the other from North America, none of the above-men- 

 tioned resinous substances were obtained. 



Mr. Hatchett now proceeds to mention a variety of experiments 

 made on horse-chestnuts, and on their peels. From these it appeared, 

 that the small portion of tannin originally contained in horse-chest- 

 nut peels is destroyed by the process of roasting ; but that the brown 

 decoctions of the roasted horse-chestnuts, and of their peels, might 

 be made to afford the tannin matter, by the addition of nitric acid. 

 The above brown decoctions appeared to contain carbon, combined 

 with oxygen, sufficient to give it many of the properties of coal ; but 

 the compound is nevertheless capable of being dissolved by water 

 with great facility. 



Solutions similar to the above may, our author thinks, be obtained 

 whenever vegetable matter undergoes the putrefactive process, as in 

 dunghills, &c. He examined the brown liquor that runs from walnut- 

 peels when kept in a heap for a certain time, and found that, like 

 the decoctions above mentioned, it contained carbon in a state ap- 

 proaching to coal, and that, by the addition of nitric acid, a small 

 portion of the tanning substance might be procured from it. 



Some experiments were likewise made upon galls ; the results of 

 which showed, that the natural tannin contained in them is destroyed 

 by nitric acid ; that it is also diminished, and ultimately destroyed, 

 by roasting ; but when the galls have not been so much roasted as 

 to destroy the whole of the tannin, the remainder of that substance 

 is destroyed by the addition of nitric acid, whilst, at the same time, 

 a small portion of the artificial tannin is produced. 



Results nearly similar were obtained from experiments upon oak- 

 bark ; and it also appeared, that when that bark was exhausted of 

 its natural tannin, it might, by roasting and being treated with nitric 

 acid, be made to yield the artificial tanning substance. This process 

 was several times repeated upon the same portion of bark ; and as it 





