THE BLOOD. 51 



and taken out at the end of half an hour ; when the blood was 

 found to be still fluid, though rather more viscid than natural ; 

 but, after being exposed to the air, it coagulated. 



EXPERIMENT XXIII. 



Two pieces of the jugular vein of a dog, just killed, were put 

 into water, in which the thermometer stood at 41; one was 

 taken out after twenty minutes, and the other after three quar- 

 ters of an hour ; the blood in both was found to be fluid, and 

 to coagulate afterwards. 



As it was evident from these experiments, that the water had 

 lessened the disposition of the blood to coagulate, I next in- 

 quired to what property in the water this effect could be owing ; 

 and to see whether water that was warmer would not have the 

 same effect, I made the following experiment. 



EXPERIMENT XXIV. 



On December the 13th, I cut out two pieces of the jugu- 

 lar vein of another dog, immediately after his death. One 

 piece was put into cold water, and the other into water kept 

 warm by a lamp, so that the heat never varied more than be- 

 tween 90 and 100. At the end of three quarters of an hour, 

 that in the warm water had in it a coagulum as large as a 

 garden-pea; but that in the cold water, being let out into a 

 cup, was quite fluid. Twenty minutes after being exposed to 

 the air, that which had been in the cold water was coagulating ; 

 but that from the warm water neither then nor afterwards 

 showed any signs of farther coagulation : so that it seemed not 

 only to have jellied whilst in warm water, but to have begun 

 to part with its serum. From this experiment, it seems pro- 

 bable that the coldness was that property of the water to which 

 the lessened disposition to coagulate was owing ; but to be more 

 sure of this, and to see whether the blood might not be kept 

 fluid a longer time by these means, I tried, as follows : 



EXPERIMENT XXV. 



On January the 14th, I cut out a piece of the jugular 

 vein of another dog, and put it into oil, in which the thermo- 

 meter stood at 38. At the end of six hours it was taken out, 

 and the red particles were observed through the coats of the 

 vein to have mostly settled to one side. The blood was let out 



