ALKALI-ALBUMIN. 109 



the prolonged action of alcohol coagulate egg-albumin ; and mer- 

 curic chlorid, nitrate of silver, and lead acetate precipitate it, 

 forming insoluble compounds. 



I/actalbutnin. This physiologic ingredient occurs in the 

 milk together with two other proteids, caseinogen and lactoglobu- 

 lin. Half-saturation with ammonium sulphate precipitates the 

 caseinogen and lactoglobulin, and the lactalbumin which remains 

 in solution may be precipitated by saturation with sodium sulphate. 

 A temperature between 70 and 80 C. (about 77 C.) will coagu- 

 late it. Unlike serum-albumin, it consists of but a single proteid. 

 Its percentage composition is: C, 52.19; H, 7.18 ; N, 15.77; 

 S, 1.73; O, 23.13. 



Myo-aibumin. This is the albumin of muscle, and resembles 

 serum-albumin. 



ALBUMINATES. 



The members of this group are sometimes described under the 

 name derived albumins, because they are derived from albumin by 

 the action of acids or alkalies. Globulins, when treated in the 

 same manner, also produce albuminates. When a mineral sub- 

 stance is added to a solution of albumin, a new compound is 

 formed, which is denominated an albuminate of the mineral, but 

 as such products are not physiologic ingredients we shall not con- 

 sider them. Albuminates are insoluble in water and neutral solu- 

 tions containing no salt ; soluble in acids, alkalies, and dilute saline 

 solutions ; precipitated when saturated with sodium chlorid or 

 magnesium sulphate ; and are not coagulated by heat. 



Acid-albumin. This is the product of the action of a dilute 

 acid hydrochloric, for instance upon an albumin. In this con- 

 version the proteid undergoes important changes. Its solution is 

 not coagulated by heat, and when it is neutralized the proteid is 

 precipitated. The conversion from the native to the acid-albumin 

 is gradual, and is hastened by heat, care being taken that the tem- 

 perature is not sufficiently high to coagulate it. Globulins are 

 likewise converted into acid-albumins by the same means, but 

 more readily, while coagulated proteids or fibrin require the acid 

 to be concentrated. 



By some writers the term syntonin is applied to the particular 

 acid-albumin resulting from the globulin myosinogen ; while others 

 use it as a synonym for acid-albumin in general. 



The point of special physiologic interest in connection with 

 acid-albumin is that in the process of stomach-digestion it is one 

 of the products. 



Alkali-albumin. As acids acting upon albumins and globu- 

 lins produce acid-albumin, in a similar manner alkalies produce 

 alkali-albumin. There is an interesting historic point in connec- 

 tion with this proteid. Mulder found that by heating albumin 



