Chloroform, Prussic Acid, &e., on the Blood. 11 



out after the mode of investigation which I have endeavoured to 

 follow, namely, the general action of a chemical substance on the 

 blood withdrawn from the body, and traced out by the microscope ; 

 and also the investigation of the action of the same agent on the 

 blood after it has circulated through the animal economy, having 

 been thereby subjected to the continuous action of air during its 

 passage through the lungs. In the former instance we obtain a 

 general kind of action on the blood ; in the latter, more positive or 

 distinct effects are presented to our notice, as I shall endeavour to 

 point out by-and-by. 



The examination of the blood drawn from the circulation and 

 subjected to the action of a chemical agent does not suffice to show 

 us all that may be produced on it by that agent, and we need, if it 

 is possible, to ascertain and compare its effects after it has circulated 

 in the system. This is true, however, only to a certain extent, for 

 we know that magenta has a remarkable effect on the blood when 

 added to it ; but we find no trace of its effects on that fluid when 

 we inject it under the skin, or pass it into the stomach with a view 

 to its absorption and subsequent action on the blood, as the experi- 

 ments of Professor Halford go to show. 



I now pass on to the examination I have made of the action of 

 one important chemical agent, which has only lately been brought 

 before the notice of the medical profession, both here and at home, 

 or rather in Europe, I mean chloral, or as its more chemical name 

 is supposed to be, "' Trichloric Aldehyde," This substance is now in 

 use as a hydrate, and its action has been stated to be somewhat 

 hke chloroform. When an alkaline solution is added to it, chlo- 

 roform is set free ; hence its proposer, Liebreich, suggested its use : 

 that meeting with alkaline elements in the blood, it might become 

 decomposed into chloroform. This theory, which is a very taking 

 one, was no doubt the cause of the experimental use of this sub- 

 stance. The general experience, however, of the profession is 

 against the idea that it acts as an anaesthetic, but only as a true 

 hypnotic. 



I feel inclined to the opinion that though it appears almost 

 certain that chloroform is eliminated in the blood by its decomposi- 

 tion, yet that the action of that agent is considerably modified by 

 the attendant chemical change which necessarily accompanies the 

 decomposition of this agent in the blood. If it is correct that 

 the hydrate of chloral is decomposed by the alkaline state of the 

 blood, then it follows as certainly that the resulting compounds 

 must be chloroform and a formate of some alkah. And if we regard 

 the presence of alkalinity to be normal in the blood, then we obtain 

 not only the chemical or physiological action of chloroform, but we 

 have also to consider what may be the physiological effect of the 

 formate of an alkali, whether of ammonia or potassa, and on such 



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