with Animal and Fegetalle Suhitances. 445 



soluble, and which again dissolve, the acid being saturated 

 with ammonia, or with either of the other alkalis, and in 

 which albumen is no\vi«e altered. If on the contrary the 

 acid is very strong and concentrated, the precipitates formed 

 will always be acid, but will contain albumen in the state 

 in which it exists when concreted by fire: this has appeared 

 in treating the precipitates with a weak sokuion of am- 

 monia. In the first instance, the solution will be gradu- 

 ally formed and complete ; in the second, the acid alone 

 will be taken up, and the albumen will remain undissolved 

 in the form of a thick magma. 



The combination of picromel with the acids took place 

 with the same faciHly as with the preceding. Almost as 

 soon as these substances con)e in contact, an acid precipi- 

 tate is formed, which redissolves when neutralized. It is 

 principally with the sulpluiric, nitric, and muriatic acids 

 that picromel forms slighllv soluble compounds. 



Theconcenlraled nitric acid is the only one, according to 

 Messrs. Fourcrf.?^- and and Vauquelin, that precipitates urea 

 from its solution in water ; yet it is probable that the other 

 acids are capable of combining with it; and if they do not 

 precipitate it, it is btcause the compounds are soluble in 

 water. I have observed that these combinations never form 

 when the temperature is below 40 or 50, particul.-rly with 

 the sulphuric and muiiatic acids; and that otherwise there 

 is a diseng'Jiieuicnt of caibonic acid, and a production of 

 a large quantity of ammonia. 



Lastiv, gelatin itself may unite with some acids, and 

 principally with iht: oxy-muriaiic acid. To tfFi.ct this 

 combination it is necessary to pass the uaseons acid through 

 a solution of gelatin. In this operation the solution gradu- 

 ally becomes turbid and prtciijilates flakes, which uinte to- 

 gether in the form of jiearly filaments very clastic and flex- 

 ible; These flakes have been considered by M. jjouillon- 

 I,.agranire, in a memoir upon the gizzards of birds, as the 

 oxygenated gelatin * : hut it is a mistake ; they are really 

 tornicd t)f gelatin slightly altered, aiid of the muriatic and 

 oxy- muriatic acids. Their striking cliaraclerislics ate, that 

 they are insipid, i-isoluble both in water and alcohol, not 

 liable to putrefy, slightly acid ; though a sufficiently large por- 

 tion of acid enters their composition to emit spontaneously 

 f.)r seveial days the i)xy-muiiaticaeid gas, nuich more may 

 be disengaged by means of heat : lastly, ihey contain so 



'•if Aiiiialts dc Chiv** tome Ivi. \i. iil. 



uuicU 



