234 THE BLOOD. 



muriate and the phosphate of soda and the phosphate of lime. 

 These saline substances were discovered by diluting serum 

 with water, and exposing the mixture to heat, by which the 

 albumen was coagulated into flocculi ; these flocculi were sepa- 

 rated by filtration ; the liquor was then diminished by evapora- 

 tion, and the salts obtained from it by crystallization. 



Serum likewise contains a portion of sulphur combined with 

 ammonia. 



When it is exposed to a coagulating heat, a small portion of 

 it remains fluid. 



This fluid portion has been supposed to contain a considera- 

 ble quantity of gelatine ; but it is contended by Mr. Brande,* 

 that Gelatine does not exist in the serum of the blood, and 

 that this portion consists of albumen combined with a propor- 

 tion of alkali. 



It is also asserted by Dr. Bostock,f one of the later writers 

 on the subject, that the serosity of blood, (the term applied to 

 the last mentioned fluid,) contains no gelatine ; but that, with 

 a minute quantity of albumen, it consists of a large portion of 

 an animal matter, which is different either from gelatine or 

 albumen, being unlike either of them, in its chemical qualities. 



The Crassamentum 



Is rendered very different in its appearance, by the different 

 circumstances in which it may coagulate. 



When the blood remains at rest immediately after it is drawn, 

 the crassamentum forms in it is a concrete substance, without 

 the smallest appearance of fibre in its composition. If the 

 blood be stirred with a rough stick, while it is flowing from an 

 animal, a large portion of it will concrete upon the stick in a 

 fibrous form, so as to resemble a mass of entangled thread, some 

 of the red coloring matter still adhering to it. 



The crassamentum, in either of these forms, may be washed 



* In his Researches on the Blood, communicated to the Royal Society of 

 London, in 1812, and republished in the Eclectic Repertory, for April, 1813. 



f See his Observations on the Serum of the Blood, in the Medico-Chirurgical 

 Transactions, vol. ii, republished in the Eclectic Repertory, for October, 1812. 



