354 Dr. Thomson's Chemical Analysis 



One hundred parts of the crassamentum, No. 4 (p. 350.)? were 

 treated in the same way. The constituents were, 



Water 6066 



Solid matter 39-34 



10000 

 The dried crassamentum was of a very dark brown colour : 

 it contained (as is known) fibrin, colouring matter, albumen, 

 and certain salts. The proportion o^ fibrin was determined 

 by washing a certain quantity of the crassamentum (usually 

 about 1700 grains), placed while moist on a cotton cloth. 

 W ater was passed over it as long as it acquired a red colour, 

 and care was taken to break all the clots in the crassamentum, 

 so as to enable the water to carry off the whole of the colour- 

 ing matter. The fibrin thus left on the cotton cloth was buff- 

 coloured, the quantity of it from 1752-69 grains of moist cras- 

 samentum was 9-76 grains. This was from the specimen of 

 blood marked No. 1 (in p. 349.). When this fibrin was dried it 

 became brown ; it was not in strings as common fibrin usually 

 is, but in scales, which were translucent and brittle, and very 

 similar in appearance to albumen dried by exposure to heat 

 upon a glass. It was insoluble in water. When digested in 

 acetic acid it became a white jelly; this jelly dissolved when 

 digested in water, and the solution was precipitated white by 

 prussiate of potash. These characters belong to fibrin, and 

 not to albumen. 



The colouring matter was determined by evaporating the 

 water employed to wash the crassamentum to dryness in a 

 temperature rather under 212°. This water had at first a 

 fine red colour ; but in a day or two it became blackish red, 

 and continued so till evaporated to dryness : the dry mass was 

 dark brown. 



To determine the quantity of saline matter, a portion of the 

 dry colouring matter was burnt in a platinum crucible. The 

 residue, which was black, was washed with water, and digested 

 in muriatic acid, and again heated to redness. By repeating 

 this process, almost the whole of the ashes were dissolved either 

 in water or muriatic acid ; the watery solution contained com- 

 mon salt and traces of an alkali. The portion dissolved in mu- 

 riatic acid consisted of 



Peroxide of iron 0-57 



Phosphate of lime 040 



0-97 

 It contained also a trace of a sulphate. 



The 



