and Observations on the component Parts of Membrane. 389 



in water, yielded a precipitate, by the addition of acetous or 

 muriatic acid ; and the precipitate was re-dissolved, when the 

 acid was added to. excess. 



12. This precipitate, when collected on a filter, appeared 

 more saponaceous, and less viscid, than that obtained from the 

 substances lately examined.* When gently heated, some oil 

 flowed from it ; after which, a brownish viscid substance re- 

 mained, similar in its properties to that which was obtained from 

 the animal soap made by tortoise-shell, and the other bodies.-f- 



13. It may not be improper here to repeat, that inspissated 

 albumen, long boiled with distilled water, was not apparently 

 diminished;, but the water (like that in which tortoise-shell, 

 quill, or nail, has been boiled) had acquired the property of 

 becoming white and turbid, when nitro-muriate of tin was 

 added, although it was not changed by the tanning principle. 



To this also may be added, that the water in which tortoise- 

 shell, nail, and albumen, had been boiled, became in some 

 measure putrid in a few days, and emitted an offensive smell. 



I am not inclined, however, to regard this as a proof that any 

 gelatin had been separated from these bodies by means of boil- 

 ing water, but rather that inspissated albumen, tortoise-shell, &c. 



* TMs precipitate, when obtained from different substances, such as hair, wool, 

 and muscular fibre, appeared in some cases more, and in others less viscid, although 

 similar in every other property. 



It wil. be proper also here to observe, that the saponaceous solutions were always 

 filtrated, before the addition of the acids. 



f The yolk of eggs, when boiled with caustic lixivium of potash, forms a pale 

 olive- coloured concrete animal soap, which, when dissolved in water, and saturated 

 with muriatic acid, is precipitated in the state of mere fat. 



Yolk of egg, by incineration, affords a small portion of phosphate of soda and 

 of lime. 



