346 PHILOSOPHY OF ZOOLOGY. 



When the coagulated serum is heated in a silver vessel, 

 the surface of the metal is blackened, being converted into 

 sulphuret. This is the proof brought forward, that the 

 serum contains sulphur ; but the previous demonstration of 

 the existence of albumen rendered it unnecessary, since 

 into that substance sulphur appears to enter as an ingre- 

 dient of its constitution. 



Clot. The clot, or crassamentum, as we have already 

 stated, consists of the coloured particles which were sus- 

 pended in the serum, and with which a portion is still me- 

 chanically mixed. If upon the clot, (in a great measure 

 freed from the serum, by cutting it into thin slices, and 

 pressing it upon blotting paper,) cold water be poured, the 

 colouring matter is removed, and the portion which re- 

 mains exhibits the properties of fibrin. 



The colouring matter is not dissolved by the water, but 

 merely mechanically suspended, and gradually subsides 

 when allowed to rest. When thus mechanically diffused, 

 the colouring matter coagulates by heat, and may readily 

 be obtained upon a filter. This matter appears to be a 

 substance intermediate between fibrin and coagulated albu- 

 men, but distinguishable from both, by the colour which it 

 retains, and the salts which it yields by incineration *. 



LEMEEY, and several of the earlier chemists, discovered 

 iron in the blood. SAGE and GREEN considered that it 

 existed in combination with phosphoric acid. FOJRCROY 



BE&ZEZ.IUS found that 400 grains of colouring matter, when burnt, 

 yielded 5 grains of ashes, composed of 



Oxide of Iron, 50.0 



Sub-phosphate of iron, 7.5 



Phosphate of lime, with a small quantity of magnesia, 6.0 



Pure lime, - 20.0 



Carbonic acid, and loss, 16.5 



100.0. 



A nnn's of Phil. vol. ii- p. 197. 



