152 THE BLOOD. 



coagulation, after escape from the body, is said to be acc'ele- 

 rated by motion, a high temperature, and a vessel calculated to 

 preserve its temperature, by a vacuum, and by the stream from 

 the blood-vessel being slow, and vice versa: in short, by every cir- 

 cumstance which favours the escape of carbonic acid gas, and to 

 be proportioned to the quantity of carbonic acid gas evolved ; this 

 being evolved during the coagulation, and ceasing to escape 

 when the coagulation is complete. 11 Galvanism and oxygen gas 

 raise its temperature and hasten coagulation, while carbonic acid 

 gas, azote, and hydrogen, have the opposite effects. Dilute mi- 

 neral acids coagulate the blood : alcalies and their carbonates 

 retain it fluid. 



The coagulation of the blood is ascribed by J. Hunter to its 

 life * ; by Mr. Thackrah k, on the contrary, to its death, as the 

 separation of a portion from the mass, by escape from a vessel, is 

 likely to kill it if alive ; as every change likely to impair life 

 promotes coagulation, for example, debility, fainting ; and as 

 blood frozen, and therefore likely to be killed if alive, and again 

 thawed, instantly coagulates. But the coagulation appears, in 

 most instances, if Sir C. Scudamore's experiments be accurate, 

 though others have not found the same results ', attributable 

 merely to the escape of carbonic acid ; and as coagulated blood 

 or fibrin (and the coagulated part of effused blood is fibrin) 

 becomes vascular, one can hardly, if the fluid is alive, regard a 

 coagulum as necessarily dead. " 



Large quantities of blood are found fluid in every dead body, 

 showing that simple loss of vitality is not sufficient to cause coa- 

 gulation. Indeed, the blood of the various parts of the heart and 

 vessels is found, most frequently, in opposite states, fluid in one 

 part, coagulated in another ; yet it is all equally dead. From all 

 these contradictory circumstances, I regard the coagulation of the 

 blood as quite unconnected with its vitality or lifelessness, and as 

 entirely a chemical result. That it, however, is influenced by the 

 vital properties of the containing vessels is possible, but these 

 may operate upon the blood, in this respect, as a mere chemical 

 compound; and even, if it be alive, and they influence its life, 

 still the influence, as far as respects coagulation, may in effect 

 be chemical. 



h Scudamore, 1. c. s A Treatise on the Blood, &c. 



k An Enquiry into the Nature and Property of Blood. By C. Turner Thack- 

 rah. London, 1819. 



1 Dr. Turner, Elements of Chemistry, 1827. p. 638. 



