30 ORGANIC CONSTITUENTS. 



precipitate is treated witli water, wliicli dissolves the pyin : any 

 albumen that may be dissolved at the same time, can be coagu- 

 lated by heat, and removed by filtration ; and in this manner 

 a tolerably pure solution of pyin is obtained. Vogel did not 

 succeed in obtaining it ; and from Simon's researches it would 

 hardly appear to be a constant constituent of pus, and purulent 

 sediments. 



Pyin is soluble in water and aqueous alcohol, but not in 

 alcohol of "865, or stronger. It does not coagulate on boiling. 

 When thoroughly dried it forms a gray powder, which does not 

 admit of being perfectly redissolved in water. Acetic acid, 

 tannin, and alum throw down precipitates, which are insoluble 

 in an excess of the test. Ferrocyanide of potassium does not 

 precipitate a solution of pure pyin ; but on the addition of a 

 little hydrochloric acid, a precipitate appears, which immediately 

 vanishes on the addition of a little more of the acid. Accord- 

 ing to IVIulder, it is identical with tritoxide of protein. 



Diagnosis of pyin. Pyin may be recognized by its reactions 

 with acetic acid and alum. It may be distinguished from the pro- 

 tein-compounds (albumen, fibrin, casein,) in the same manner 

 as pepsin and glutin. It differs from pepsin, by its acetic-acid 

 precipitate not re-dissolving in an excess of the test, and from 

 glutin and chondrin, by a similar behaviour on the part of the 

 alum precipitate. 



9. Extractive Mattel's. 



After the removal of the protein-compounds from the animal 

 fluids, there still remain certain salts, (lactates, chlorides, phos- 

 phates, and sulphates,) together with organic nitrogenous matter, 

 which after evaporation remain as an amorphous mass. It is to 

 this organic nitrogenous matter, after the salts have been re- 

 moved by their appropriate solvents, that the term extractive 

 matter is applied. It is as generally diffused over the whole 

 system as the protein-comi)ounds ; we meet with it in blood, 

 bile, milk, urine, mucus, pus, and all the soft tissues, and most 

 abundantly in muscular flesh. Hence the extractive matter of 

 flcsli merits especial attention. The extractive matters from 

 other sources, as from blood, urine, milk, &c., will be subse- 

 quently noticed, and their leading characters contrasted with 

 those of our standard extractive matter, the extract of flesh. 



