170 CIRCULATORY SYSTEM. 



horses' blood are,— 1st. That the latter much more slowly resolves 

 itself into its component parts ; and, secondly, that it possesses 

 greater preservative powers against putrescency. 



Serum itself exposed to the temperature of 160° is converted 

 into a solid, white, opaque mass ; also the effect of coagulation. 

 Mineral acids and alcohol will likewise produce this change. It 

 now resembles boiled white of egg; and is found, in fact, to be 

 the same in nature, viz. albumen. If this coagulum be cut or 

 squeezed, a limpid fluid issues from it, that has been termed the 

 serosity. 



"The most important chemical properties of albumen," ob- 

 serves Dr. Bostock, "while in its liquid form, are its solubihty 

 in water, and the precipitates which it forms with the mineral 

 acids, tan, and a variety of metallic salts. Of the acids, the 

 muriatic is supposed to combine with it the most readily, and is 

 therefore employed as one of the most delicate tests^of its pre- 

 sence in a substance where we expect it to exist. Tan forms 

 with albumen a dense precipitate of tough consistence, and inso- 

 luble in water. A variety of the metallic salts precipitate albumen, 

 and, like the acids, serve as very delicate tests of its presence; of 

 these probably the corrosive sublimate, or the bichloride of mer- 

 cury, IS the most delicate, and at the same time the most dis- 

 criminate, as it appears to have no action upon any other of the 

 animal substances which enter into the composition of the albu- 

 minous fluids," When coagulated, albumen becomes completely 

 insoluble in water. 



The serosity exists in a comparatively very small quantity, 

 and can only be obtained by slicing the albuminous coagulum 

 and allowing it to drain, or else by expression, or by washing it in 

 water. It has been particularly examined by Dr. Bostock, and 

 found to contain an animal matter which is not albumen; and 

 whose nature it is difficult to make out, in consequence of its 

 being always found united with soda, and a variety of other salts, 

 from which it cannot be separated, without being, at the same 

 time, decomposed. To this substance Dr. Marcet has applied 

 the name of muco-extractive matter; while Dr. Bostock prefers 

 styling it the uncoagulable matter of the blood. 



BUFFY COAT — CUPPED BLOOD. 



I make the consideration of these points a distinct one, because 

 I feel desirous to correct what I conceive to be an important error 

 practitioners have fallen into. 



Let the crassamentura be examined at the side, and the upper 

 layer of it will be found to be yellow or buff-coloured ; below 

 this, it will appear of a light red hue ; lower still, darker and 



