46 PROPERTIES OF 



four minutes in beginning to do it, after it is let out of the 

 veins (as is the case in people in health) it might coagulate in 

 less time, or almost instantaneously; for I imagined, that un- 

 less this took place, we could hardly conceive how the blood 

 should ever have time to coagulate in ruptured vessels, so as tcf 

 stop hemorrhages, as it is believed to do. And upon this oc- 

 casion I recollected a remark that I had heard, particularly 

 from Dr. Hunter, which is, " That the faintness which comes 

 on after hemorrhages, instead of alarming the bystanders, and 

 making them support the patient by stimulating medicines, as 

 spirits of hartshorn and cordials, should be looked upon as 

 salutary; as it seems to be the method Nature takes to give 

 the blood time to coagulate." Now as this seemed to favour 

 my suspicion, I determined to make the experiment. 



EXPERIMENT XXI. 



Believing it would be sufficient for this purpose, to attend to 

 the properties of the blood, as it flows at different times from 

 an animal that is bleeding to death, I therefore went to the 

 markets, and attended the killing of sheep ; and having re- 

 ceived the blood into cups, I found my notion verified. For I 

 observed, that the blood which came from the vessels imme- 

 diately on withdrawing the knife was about two minutes in 

 beginning to coagulate ; and that the blood taken later, or as 

 the animal became weaker, coagulated in less and less time ; 

 till at last, when the animal became very weak, the blood, 

 though quite fluid as it came from the vessels, yet had hardly 

 been received into the cup before it congealed. I have also 

 repeated the experiment, by receiving blood into different cups 

 at different times, whilst the animal was bleeding to death; 

 and though the time taken up in killing the animal was not 

 commonly more than two minutes, yet I observed, on compar- 

 ing the cups, that the blood which issued last coagulated first 1 



1 It may be necessary to mention a circumstance that has occurred in repeating 

 these experiments ; which is, that although the last cup being taken from the animal 

 when much reduced, always coagulated in less time than the first, yet, when four or 

 five cups were used, the blood in them did not always coagulate precisely in the in- 

 verse order of their being filled ; for sometimes the second coagulated before the third. 

 This circumstance at first seemed contradictory to the general conclusion, but on a 

 more careful examination, it was suspected to be owing to the straggles (or temporary 

 exertion of strength of the vessels) of the animal, and no difference was observed in 

 the exposition to cold or to air. 



