1904.] Properties of Solutions of Chloroform in Water, etc. 389 



II. — On the Relative Solubility of Chloroform in Water, Saline, Serum, 

 and Haemoglobin Solution. 



In so far as we have been able to discover, no attention has been 

 paid by previous experimenters to the maximum amount of chloroform 

 capable of solution in the blood or serum as compared with that taken 

 up by water or saline solution isotonic with blood. 



When any reference is made to the matter it has been usually assumed 

 on general principles that the serum or plasma will behave like a 

 saline solution of equal concentration and dissolve somewhat less 

 chloroform than water.* In other words, that there is no specific 

 action of the proteids or other substances in the plasma. 



This supposition we have found experimentally to be entirely 

 erroneous, for both serum and solutions of haemoglobin dissolve much 

 more chloroform than water or normal saline solution. This fact is of 

 importance in regard to the mode of action, as it definitely points to 

 an interaction between the chloroform and the proteid present. 



The presence of fats would of course increase the apparent solubility 

 of chloroform in serum, and hence it is necessary in all cases to use 

 perfectly clear serum, free from suspended fat ; this precaution we have 

 always been careful to observe, and in addition the serum has always 

 been centrifugalised. 



In this connection it may be added that the haemoglobin solutions 

 which we have employed could not contain fatty matter, and hence 

 the high solubilities which we have observed could only arise from 

 chemical interaction between the haemoglobin and the chloroform. 



Methods for Determining Maximum Solubility. 



Three methods have been used in the determination of the maximum 

 solubility of chloroform in the solvents mentioned above, which have 

 given concordant results and shown that the solubility in proteid 

 solution is much higher than in water or saline. 



In the first method we have determined the amount of chloroform 

 dissolved by obtaining the product of volume and vapour pressure at 

 low pressure and with a small volume of fluid, so that practically all 

 the chloroform was simply pumped off into the vacuum. In this 

 method the volume of fluid experimented with is necessarily small, 

 and this gives rise to experimental error of measurement, which is 

 added to by the volume measured being large and pressure small, so 

 that the results are only approximative, yet it is observable that they 

 confirm those obtained by the more accurate methods described below. 



The details of the method are described in the succeedino; section 

 on the relationship between vapour pressure and concentration of 



* Overton, ' Studien liber die Narkose,' p. 93. 

 VOL. LXXIII. 2 E 



