22 Chemical Properties of Animal Fluids. [July, 



of this excess of acid, by means of pure water, a neutral com- 

 bination is obtained, which is soluble in water, and possesses the 

 same characters as the neutral muriate of fibrin. 



6. Nitric acid of the specific gravity 1*25 digested with fibrin, 

 renders it yellow, and diminishes its cohesion. The fluid becomes 

 yellow, and the surface of the fibrin is covered with a small 

 quantity of fat formed by the action of the acid. During this 

 operation elastic matter is disengaged, winch is azotic gas alone, 

 and in which I could not discover the smallest portion of nitrous 

 gas. When the digestion has been continued 24 hours, the 

 fibrin is converted into a pulverulent mass, of a pale citron 

 colour, which is deposited at the bottom of the liquor. The 

 latter being decanted off, and the undissolved matter placed on 

 a filter and washed with a large quantity of water, the colour 

 changes in proportion as the acid which was in excess is carried 

 off, and the mass acquires a deep orange colour. Even when the 

 affusion is continued tjll the water gives no sign of acidity, the 

 orange mass has not yet lost the property of reddening litmus. 



This yellow substance was discovered by Messrs. Fourcroy and 

 Vauquelin, who obtained it in treating muscular flesh with nitric 

 acid. They have described it as a new acid formed by the action 

 of nitric acid on the muscular fibre, and to which, from its 

 colour, they have given the name of yellow acid. (Acidejaune.) 

 This substance is dissolved in caustic alkali, to which it imparts 

 an orange colour, and it is partly soluble in acetate of potash and 

 of soda. The French chemists found that, if treated with a fresh 

 quantity of nitric acid, it acquires the property of burning with 

 the same phenomena as a confbustible body mixed with nitre. 

 This fact they considered as remarkable, since they couldtiot 

 detect any nitric acid in the yellow acid. But the latter, as will 

 be presently shown, is nothing more than a combination of 

 fibrin with nitric acid, (or in other cases, perhaps, with nitrous 

 acid,) and also with another acid formed by the decomposition 

 of a portion of the fibrin, a species of combination very ana- 

 logous to the one already described. If the yellow substance be 

 boiled with alcohol, a yellow adipocirous matter is taken up; but 

 it is deposited when the liquor cools. This sebaceous matter has 

 a great resemblance to that obtained by the action of alcohol on 

 pure fibrin. If the yellow substance, after being thus deprived 

 of its adipocirous portion, be digested with water and carbonate 

 of lime, it slowly decomposes the carbonate, disengages its acid 

 in the form of gas, and produces a yellow solution. Having 

 separated this fluid from the undissolved portion of the yellow 

 substance, I concentrated it to the consistence of a syrup : and 

 then poured in alcohol, which precipitated one part, retaining 

 the other in solution. The precipitate had all the characters of 

 jnalute of lime. Dissolved in water, and decomposed by a sufli- 



