1907.] Rate of Assumption of Chloroform by the Blood. 557 



Brodie and Widdows* have published the results of work undertaken on the 

 third line, and the last observers have ascertained that the assumption of 

 chloroform is much more rapid in the earlier than in the later stages of 

 anaesthesia. We believe that by this method only a very limited amount of 

 information can be gained as to the physiological processes which are 

 concerned in anaesthesia. With the desire of throwing further light on this 

 question, we have undertaken a number of experiments on the chloroform- 

 content of the blood during the stages of anaesthesia. A very large number 

 of experiments have been made, of which we quote three of the most 

 detailed ones, which are typical of the whole. 



Mode of Experiment. 



The general mode of the experiment has been described in detail in 

 a former paper.f The method we have now followed is similar, except that 

 nitrous oxide was used instead of ether as the first anaesthetic. The effect 

 of this gas was allowed to pass off and then chloroform was administered. 

 We found some difficulty in maintaining the chloroform-content of the 

 inspired air absolutely constant. The best mode of attaining this is by 

 means of goldbeater's skin bags filled with a definite percentage of 

 chloroform vapour by means of the Dubois apparatus, and this was the 

 method adopted in some of the experiments. The apparatus gives fairly 

 good results within the limits for which it is constructed, i.e., up to 

 percentages of 2, but above this value it is difficult to obtain constantly 

 good results. It is also necessary that the goldbeater's skin bags shall be 

 new and made of fresh skin, as it was found that with old bags, even if these 

 were perfect, the contents became gradually weaker in chloroform, and 

 direct experiments showed that this was due to the absorption of chloroform 

 vapour by the material. With fresh goldbeater's skin this did not occur.| 

 All the tubes used in making connection with the bags or cannula in the 

 trachea should also be of wide bore, not less than J inch, and rubber 



* Brodie and Widdows, 'Brit. Med. Journ.,' June, 1906. 



t ' Koy. Soc. Proc.,' B, vol. 78, p. 422. 



J Aspiration of a mixture of chloroform vapour and air from an old goldbeater's skin 

 bag. Weight of chloroform determined densimetrically. 



In one experiment the weight of chloroform progressively fell in three-quarters of an 

 hour from 0*045 to 0*032, and with a larger bag the progressive fall was from 0*023 to 

 0*01 in 20 minutes. 1*1 grammes of the skin of this bag, suspended in air containing 

 chloroform vapour, increased in weight 0*026 gramme, while a similar control in air 

 increased only 0*0015. An experiment with fresh skin showed practically no change in 

 weight. A new bag, 36 inches in circumference, the content of which was analysed at 

 regular intervals, showed no variation in an hour, though a slight decrease in the amount 

 of chloroform took place on prolonged standing. 



