6 PROPERTIES OF 



which gives the red colour to the blood, and is called the red 

 globules. These two parts can be separated by washing the 

 crassamentum in water, the red particles dissolving in the 

 water, whilst the coagulable lymph remains solid. That it is 

 the coagulable lymph, which, by its becoming solid, gives 

 firmness to the crassamentum, is proved by agitating fresh 

 blood with a stick, so as to collect this substance on the stick, 

 in which case the rest of the blood remains fluid 1 . 



The surface of the crassamentum, when not covered with a 

 size, is in general of a more florid red than the blood was 

 when first taken from the vein, whilst its bottom is of a dark 

 colour, or blackish. This floridness of the surface is justly 

 attributed by some of the more accurate observers to the air 

 with which it is in contact ; for, if the crassamentum be in- 



1 It may be proper to mention here, that till of late the coagulable lymph has been 

 confounded with the serum of the blood, which contains a substance that is likewise 

 coagulable. But in these sheets, by the lymph, is always meant that part of the blood 

 which jellies, or becomes solid spontaneously when blood is received into a basin, 

 which the coagulable matter that is dissolved in the serum does not ; but agrees more 

 with the white of an egg, in remaining fluid when exposed to the air, and coagulating 

 when exposed to heat, or when mixed with ardent spirits, or some other chemical 

 substances. 



at a lower heat than pure serum ; and the less water there is in serum, 

 or in other words, the greater the proportion of albumen, the lower is 

 the temperature required for its coagulation. Liquor sanguinis kept 

 fluid by salt is only affected by heat like a concentrated serum. 



h. A fresh mixture of liquor sanguinis and salt, diluted with four or 

 five parts of distilled water, generally coagulates in less than twenty-five 

 minutes at 65; its coagulation is hastened by any degree of heat 

 upwards to 123; most so from 96 to 114. From 124 to 127 its 

 power of spontaneously coagulating is completely destroyed; and its 

 transparency and fluidity are not lessened till the heat be raised enough 

 to produce the albuminous precipitate described above, at f. 



i. When the red corpuscles are mixed with the salted liquor san- 

 guinis diluted with water, coagulation is quickened at all temperatures, 

 just as adding corpuscles to pure blood hastens its coagulation, as shown 

 in Exp. 57-63, Edin. Med. and Surg. Journ. vol. Ixiv, p. 374. 



k. As coagulation is slower in the liquor sanguinis apart from the 

 corpuscles than with them, the retarded coagulation often observed in 

 buffy blood seems to be an effect, and not, as has been so commonly 

 supposed, a cause of the separation of the corpuscles and fibrin. 



The effects of a low temperature and of freezing on the coagula- 

 tion of blood, and on the contractility of muscle, are mentioned in 

 Note xi. 



