400 Mr. Hatchett's Experiments on Zoophytes, 



There is also much reason to believe that gelatin, although it 

 appears so different in many respects from albumen, is yet 

 formed from it* 



It may be recollected, that in a former part of this paper 

 mention was made, that tortoise-shell, horn, muscular fibre, and 

 inspissated albumen, after long immersion in very dilute nitric 

 acid, and after being well washed, were soluble in boiling water; 

 and that a substance was formed, which (by becoming liquefied 

 when heated, by being soluble in boiling water, by being preci- 

 pitated by the tanning principle and by nitro-muriate of tin, and 

 lastly, by forming a gelatinous mass when the aqueous solution 



* In addition to the chemical properties by which gelatin and albumen are dis- 

 tinguished, particularly the different effects observed when these two substances were 

 treated with nitric acid, I shall mention some others, not less remarkable, which are 

 produced by the muriatic acid. 



When any of the varieties of gelatin, such as glue, isinglass, &c. are immersed in 

 cold muriatic acid, they are dissolved in a few hours ; and the solutions thus formed 

 6uffer no apparent change, even in the course of several months. In like manner, 

 gelatin may be separated and dissolved from bodies which contain it, such as sponge, 

 bladder, skin, and muscle ; but the part which remains undissolved, and which, with 

 the other substances formerly mentioned, I regard as formed of albumen more or less 

 organized, is very differently affected ; for, when coagulated albumen, the undissolved 

 part of bladder, muscular fibre, feather, quill, tortoise-shell, wool, and hair, were 

 separately steeped in muriatic acid, they gradually became of a dark colour, and the 

 acid was tinged with the same. The colour afforded by albumen was deep blue, 

 inclining to purple ; that of bladder was brownish purple ; feather, quill, tortoise-shell, 

 and muscular fibre, afforded a beautiful deep blue ; and wool and hair, like bladder, 

 produced a brownish purple. The change began to take place in the coagulated 

 albumen in about eight or ten days ; but wool and hair were the last which were affected. 

 In about three months, the different liquids were become very dark, although scarcely 

 any perceptible quantity of the immersed substances appeared to be dissolved. Nitric 

 acid, in a small proportion, changed these blue and brownish purple liquors to deep 

 yellow ; and ammoniac, being then added, changed them to orange colour, and pro- 

 duced all those effects which were observed, when the nitric solutions of these 

 substances were thus treated. 



