6 4 o SCIENCE PROGRESS 



acid with tartaric acid, and subsequent saponification with 

 alcoholic soda or potash. The end point of the reaction is 

 a colour one, yellow potassium chromate changing to an orange- 

 red silver chromate. Buckmaster and Gardner have criticised 

 this method, not adversely or unfairly; but it was incumbent 

 to do this, since Nicloux in particular, who has performed much 

 work by this method, regards it as a very exact chemical 

 procedure, and he also believes that results obtained by methods 

 other than this one are too high. 



The principal results obtained by the French observers 

 J. Tissot, 1 Mansion, 2 and Maurice Nicloux 3 are described at 

 length in a recent paper. 4 The last observer found that the 

 anaesthetic amount varied for different individual dogs. The 

 same is true for the lethal amount, and the differences between 

 the amount required to produce an anaesthesia in which all 

 reflexes are abolished and the lethal quantity are small. He 

 also found that the quantity of chloroform present in the blood 

 at the anaesthetic stage was almost constant, and independent 

 of the weight of the animal — a conclusion really equivalent to 

 the view that the quantity of blood in the individual does not 

 modify the percentage of chloroform in the blood. Tissot's 

 observations were also carried out on dogs, and the method for 

 determining the amount of chloroform in the blood resembled 

 that employed by Nicloux. The results of Tissot's work showed 

 that anaesthesia can exist with a very low chloroform-content 

 in the blood, and that the amounts in arterial and venous blood 

 differ. During the administration of chloroform the amount in 

 arterial exceeds that in venous blood ; during recovery from 

 narcosis more of the drug will be present in venous than in 

 arterial blood. Tissot lays special stress on the point that when 

 mortal syncope or failure of the heart-beat is produced in dogs 

 with a prolonged administration of low percentages of chloro- 

 form, comparatively large amounts of the drug are found in 

 arterial blood ; but just before actual syncope occurs the amount 

 falls in a marked degree. From this fact he concludes that this 

 diminution in the blood, which is a constant phenomenon, is 



1 Cotnptes rendus de la Soc. de Biol., 1906, pp. 195, 198, 200, 203. 



2 Ibid. No. 4, 1906, pp. 206, 238, 241. 



3 Ibid. No. 2, No. 3, No. 7, 1906, and November 2, 1907, p. 391. 



4 " The anaesthetic and lethal quantity of chloroform in the blood of animals," 

 by G. A. Buckmaster and J. A. Gardner, Proc. Royal Soc, vol. lxxviii. 1906. 



