642 



SCIENCE PROGRESS 



between the chlorine-content of the blood before and after 

 anaesthetisation with chloroform was calculated, and this gave a 

 figure which could be expressed as chloroform. The whole 

 method is an entirely new one, and has never been employed 

 by earlier observers. In exactness it is believed to be preferable 

 to those methods where the determination is a volumetric one 

 with an end point which depends upon a colour reaction. Most 

 of these experiments have been carried out on cats, while other 

 observers have generally carried out their investigations on 

 dogs. The chief conclusions arrived at were that the amount 

 of chloroform in arterial blood at the moment when some 

 definite reflex action disappears varies with different individuals. 

 The same is true for the lethal amount in the blood ; but a 

 consideration of all the experiments taken together shows that 

 only a narrow margin exists between the weight of chloroform 

 in the blood at the moment of anaesthesia (loss of conjunctival 

 reflexes) and the cessation of respiration (lethal amount). 



The above outlines the methods of investigation, and enables 

 the conclusions to be represented in the following table : 



} 



Observer. 



Grehant and Quinquaud, 



1883. 

 Pohl, 1890. 

 Nicloux, 1906 . 

 Tissot, 1906 

 J. Mansion and J. Tissot, 



1906. 

 Buckmaster and Gardner, ) 



1906. J 



Buckmaster and Gardner, 



1906. 



Animal, 

 dogs 



it 



5> 



Anaesthetic amount 



of CHC1, 



50 mg. 

 18-50 mg. 



5° 

 34-4o 



/ 29 



X 32- 



43 

 16-31 



5> 

 » 



} 



cats 



reflexes just gone . 

 14-27' 5 mg. reflexes just gone 



Lethal amount 



of CHCI3. 



35 mg- 

 41-70 mg. 



60-105 „ 



61-69 mg. 



40 



From these figures, which are in fair agreement, especially 

 for the lethal dose, it would seem that the quantity of chloroform 

 required to produce various stages of anaesthesia are somewhat 

 higher in dogs than in cats. The difference, however, is not 

 great. The lethal point is fixed as that at which the respiration 

 is of a convulsive type owing to the onset of asphyxia. 



The Rate of Assumption of Chloroform by the Blood 



It is a familiar fact that when chloroform is inhaled the 

 respirations may rapidly diminish in depth and frequenc}', or 

 even actually stop within a few minutes. In the case of cats 



