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VII. — Miscellaneous Observations on Blood and Milk. By John Davy, M.D., 

 F. JR.. S., Loud, and Edin., Ins-pector-General of Army Hospitals, L. R 



(Read April 7. 1845.) 



1. On the State of Combination of the Alkali in the Blood. 



The condition of the alkali in the blood — of that portion on which its alkaline 

 reaction depends — has been the subject of much speculation, and of many experi- 

 ments. Endeeling is one of the latest inquirers who has given it his attention. 

 After having made an analysis of the ashes of the blood, he has come to the con- 

 clusion, that the alkali in it is in combination with phosphoric acid, the former 

 predominating in the form of the tribasic phosphate of soda.* 



Granting the accuracy of Endeeling's analytical results on the ashes, does it 

 follow that his inference must be coiTect relative to the condition of the alkali in 

 the liquid blood ? It appeared to me doubtful a priori ; and the doubt I enter- 

 tained was confirmed by experiment. The doubt arose from considering the ten- 

 dency of the alkaline carbonates, when strongly heated with charcoal, to be 

 reduced ; and Avhen heated with phosphate of lime in excess, to exchange their 

 carbonic acid for a portion of the phosphoric — the acid gas of course escaping, 

 and compounds of lime and alkali remaining, each with excess of base. In accord- 

 ance with this, when I have added carbonated alkali to the coal obtained from 

 blood, and have reduced the coal to ashes, I have not been able to detect in the 

 lixivium obtained from them any trace of carbonic acid. Moreover, I find that 

 the carbonate of soda is liable to loss when heated strongly, exposed to the air ; 

 and, consequently, when it exists in a small quantity in a bulky coal, the whole 

 of it may be dissipated — carried over much in the same manner as boracic acid is 

 in combination with water as a hydrate, when it is subjected to heat. 



If Endeeling's view were correct, the blood, after having been acted on by 

 the air-pump, ought not in its fresh state to yield any carbonic acid on the addi- 

 tion of an acid. This is the experiment alluded to, which confirmed my doubt. 

 I find that blood or its serum, after having been so acted on until perfectly tran- 

 quil, has effervesced strongly, when mixed either with dilute sulphuric or muriatic 

 acid purged of air, or with a solution of cream of tartar. And, in accordance with 

 this, I have also found that serum, after having been subjected to the air-pump, 

 gives on coagulation, by immersion in boiling water, a different result, whether 



* See Mr Paget's Report on the Progress of Human Anatomy and Physiology, in the British 

 and Foreign Medical Eeview for January 1845, 



VOL. XVI. PART I. O 



