10 OF THE BLOOD. 



the colouring particles have time to fall to the bottom, and en- 

 tangling them acquires a red colour, forming the crassamentum : 

 if, however, the lymph coagulate slowly, as in the phlogistic 

 diathesis, the greater specific gravity of the cruor detaches it very 

 considerably from the lymph, which remains colourless above, 

 constituting what is called the inflammatory coat, crust, or buff.* 

 Berzelius even believes the lymph to be in a state of solution in 

 the serum, while the cruor is simply suspended in this solution j 

 but the separation of the serum in dropsy, vesication, &c. led 

 Mr. Hunter to a different conclusion, f 



(E) The coagulable part of serum is albumen } that which 

 remains fluid is called serosity, — a name given it by Cullen, and 

 contains no gelatine as the French chemists asserted, but an ani- 

 mal matter different from both gelatine and albumen, with a mi- 

 nute portion of albumen and fibrine, and affords a little free soda, 

 muriate, lactate, J and phosphate, of soda, and muriate of potash, 

 with ^oVff °f water. § If mixed with six parts of cold water, 

 serum does not coagulate by heat. 



(F) When venous blood acquires a florid colour by exposure to 

 oxygen or atmospheric air, (and it does so even when covered by 

 a bladder) carbonic acid gas is formed, and an equal quantity of 

 oxygen gas disappears. If exposed to nitrous oxide, it becomes 

 of a brighter purple, and much of the gas is absorbed : carbonic 

 acid gas renders it darker and is a little absorbed, while azote 

 occasions no change. The dark colour produced in arterial blood 

 by carbonic acid or azotic gas takes place if blood is placed hi 



* In this state the albumen of the serum is also affected, for it docs not co- 

 agulate by heat as usual, and the whole mass of blood is thinner. 



f View of the present State and Progress of sfnimal Chemistry by J6ns Jacob 

 Berzelius, M. D. &c. Translated by Dr. Brunnmark. 1813. p. 23. Hunter, 

 1. c. p. 18. 



X Berzelius discovers lactic acid free or combined in all animal fluids. It 

 was first noticed by Schecle, but u generally regarded as a combination of 

 acetous acid with animal matter. 



§ Sec Dr. linstock's papers in the first, second, and fourth volumes of The 

 Medico-Chirurgical Transactions, and Bcrzclius's in the third. 



