92 PHYSIOLOGY OF THE DOMESTIC ANIMALS. 



quantity, a dense, white precipitate will be formed, and when subjected 

 to heat the precipitate will become condensed into the form of a firm 

 coagulum, and will turn red. If but a trace of albumen is present the 

 fluid will simply take on a pinkish color. 



Schnitzels Test. When albuminoids in solution are treated with a 

 cane-sugar solution in small quantities and concentrated sulphuric acid 

 then added a beautiful red color is formed. 



Adamkiewicz's Test. If a solution of an albuminous body is strongly 

 acidulated with acetic acid and sodium chloride added in bulk, and then 

 strong sulphuric acid, the fluid will gradually assume a violet-blue color, 

 slightly phosphorescent, and gradually turning dark purple. 



Frohde's Test. When a mixture of sulpho-molybdic acid is added 

 to a solution of albuminous bodies a dark-blue color is produced. 



Of the above tests the xantho-proteic and Millon's reaction may be 

 used for the microscopical detection of the albuminoids. 



Albuminous bodies may be divided into the following classes : 



I. ALBUMENS. Albumens are bodies which are soluble in water, and 

 when in solution are coagulated by heat (about 70 C.). They are not 

 precipitated from their solutions by dilute acids, carbonates of the alka- 

 lies, sodium chloride, or platino-hydrocyanic acid. When dried at about 

 40 C., or if evaporated at a lower temperature in a vacuum, they leave 

 a yellowish, friable, inodorous, gummy mass, which is still soluble in 

 water, and whose solutions possess all the properties of the original 

 solution. Albumens are precipitated from their solution by alcohol, if 

 alkaline salts are present. Albumens may exist in three different forms, 

 serum-albumen, egg-albumen, and vegetable albumen. 



1. Serum- Albumen. Serum-albumen is found in blood, serum, 

 lymph, serous transudations, and animal secretions. 



Serum-albumen may be obtained from blood-serum, or any serous transuda- 

 tion, by adding dilute acetic acid, drop by drop, until a flocculent precipitate forms. 

 This precipitate is then filtered off, and the filtrate, after neutralization with a 

 little sodium carbonate, is evaporated in a shallow dish to a small volume, not 

 allowing the temperature to rise above 40 C. The salts may then be removed by 

 dialysis, changing the water frequently outside of the dialyzer, and again evapo- 

 rating at 40 C. to dryness. 



So obtained, serum-albumen always contains a slight percentage of 

 salts, but is soluble in water, forming a clear solution, which is somewhat 

 tenacious when concentrated. 



In the dry condition it is a yellowish, brittle, transparent body 

 capable of being redissolved in water, and its solutions are then coagu- 

 lable by heat. Its solutions are opalescent, and possess a specific laevo- 

 rotation for yellow light of 56. It is precipitated out of its solutions 

 by alcohol, the precipitate being partially redissolved when the alcohol 

 is immediately poured off, but is not coagulated l>y ether. Most of the 



