38 FIBRINE. CASEINE. [CHAP. I. 



great part of which is colourless, from the cavities of the heart, 

 and from the large arteries, after death. It is also accumulated, 

 and disposed in a peculiar lamellar form, in the sacs of old 

 aneurisms. 



Pure fibrine is white, tasteless, and inodorous; it tears into 

 thin laminae, which are transparent, and it is remarkably elastic ; 

 by drying, it becomes yellow, hard, and brittle, and loses three 

 fourths of its weight, but imbibes water again when moistened : 

 it is insoluble in both hot and cold water, in alcohol, and in ether. 

 By long- continued boiling in water, its composition is changed, and 

 it becomes soluble. Strong acetic acid converts it into a jelly-like 

 mass, which is sparingly soluble in water. All the alkalies dis- 

 solve fibrine. Any of these solvents of fibrine will prevent the 

 coagulation of blood, which has been allowed to drop into it as 

 it flows from the blood-vessels. 



Fibrine is dissolved by cold concentrated muriatic acid, and, if 

 kept at a cool temperature for twenty-four hours, the solution ac- 

 quires an indigo-blue colour. Albumen, similarly treated, assumes 

 a violet colour. 



Caustic potash, common salt, carbonate of potash, and many 

 neutral salts, when mixed in certain quantities with the blood, have 

 the property of preventing the coagulation of its fibrine.* 



We subjoin the ultimate analysis of fibrine, as given by Mulder. 

 In one hundred parts, he found 



Nitrogen .... 1572 



Carbon .... 54-56 



Hydrogen .... 6-90 



Oxygen. . . . 22-13 



Phosphorus. . . . O33 



Sulphur . . . 0-36 



100-00 



3. Caserne. This principle has many properties in common with 

 albumen and fibrine. It is found abundantly in milk ; its occur- 

 rence in other fluids has not been positively determined. The curd, 

 which is formed by heating milk in which a free acid existed, 

 consists of a combination of caseine with the acid. Heat alone 

 will not effect the precipitation of the curd ; but the addition of 

 a little acid of any kind will occasion it. 



When dilute sulphuric acid is added to skimmed milk, a precipi- 



* See further observations on the results of the examination of fibrine by 

 the microscope, in the chapter on the Blood. 



