substance. 



ALBUMINOUS SUBSTANCES. 35 



Average of Most Analyses. Approximation. 



C 50.0 to 55.0 per cent. 52 per cent. 



H 6.5 to 7.3 per cent. 7 per cent. 



20.0 to 23.5 per cent. 23 per cent. 



S 0.3 to 2.2 per cent. 2 per cent. 



N 15.0 to 18.0 per cent. 16 per cent. 



Phosphorus is sometimes found in less amounts than 

 1 per cent. 



A few of the albuminous substances have been ob- 

 tained in a crystalline form, but most of them are amor- 

 phous. They differ in their solubilities and are classified 

 largely upon this basis. The peptones will diffuse through 

 an animal membrane, but they do not pass through rapidly. 



The albuminous substances, like some other organic 

 compounds which do not belong to this class, are thrown 

 out of solution when to the solution certain neutral salts 

 are added until it is saturated. Ammonium sulphate will 

 precipitate all but the peptones and perhaps a few of the 

 albumoses. Magnesium sulphate and sodium chlorid will 

 precipitate many of them. 



When the albuminous substances are heated with 

 water, many of them are coagulated, passing into an in- 

 soluble modification. The temperature at which this takes 

 place is called the coagulation-point. This is a different 

 one for most of the different substances, and may be used 

 in their identification and separation. It may vary, how- 

 ever, from the presence of other substances. It may be 

 raised, prevented, or the coagulation made incomplete by 

 alkalies or by some organic acids, like acetic acid. Coagu- 

 lation is favored and the coagulation-point is lowered in 

 the presence of neutral salts or small amounts of a mineral 



