1909.] Physiological Properties of Tetrachlor ethane, etc. 221 



Preparation of Solutions for Physiological Experiments with Frog's Sartorius 



Muscle hy Waller's Method* 



The standard taken for comparison was 7i/100 chloroform, and all data are 

 given in terms thereof ; the chloroform sample used had been prepared from 

 chloral hydrate. Solutions of chloroform, tetrachlorethane, and trichlor- 

 ethylene were made up in physiological saline solution (0-6 per cent.) to 

 wi/100 concentration by weighing out to within 1 part in 800 the quantities 

 of the several liquids required, which would be as under : — 



1"195 gramme chloroform in 1 litre = 0"119 per cent, (neglecting density 



variation of water). 

 1-315 „ trichlorethylene ., = 0'131 „ ,, 



1'678 „ tetrachlorethane „ = 0'168 „ „ 



Half these quantities were actually taken and dissolved in -|- litre saline 

 solution. The chloroform and trichlorethylene dissolved fairly readily in 

 this proportion, but the tetrachlorethane required a day or more for 

 completion. 



It was found necessary to prepare the chloroform solution afresh after two 

 or three days, as otherwise irregular results were obtained ; but whether this 

 was the result of loss of chloroform by evaporation, or some chemical change 

 between the chloroform and water in presence of daylight, or from both 

 causes, was not further investigated. 



In the preliminary experiments with the commercial products the 

 substances were weighed out as pure for lack of better data ; the errors 

 would probably amount to 8 to 10 per cent. 



The experiments were conducted in the usual manner ; simultaneous 

 records with a pair of muscles were obtained : firstly, of the normal response 

 to induction shocks when the muscles were immersed in tap-water saline 

 solution (0"6 per cent.) ; secondly, the time required for abolition of response 

 after the solutions to be examined had been simultaneously substituted for 

 the saline solution, and, thirdly, the time and degree of recovery, if any, 

 after the saline solution was in its turn resubstituted for the solutions under 

 examination. 



Preliminary experiments with commercial samples of trichlorethylene and 

 tetrachlorethane showed that the former was rather more toxic, but more 

 regular in its action, than chloroform, and that the latter was about four 

 times more toxic than chloroform ; in both cases the recovery was more 

 regular. The details with the purified materials are given in the sequel : — 



* ' Eoy. Soc. Proc.,' June, 1909. 



