1909.] 



Alcohol, Ether, and Chloroform, etc. 



547 



The exciting currents passed through the muscle and solution — principally 

 through the former by reason of the copper wires by which it is attached — 

 are taken of such strength as to give assuredly maximal effects. Their 

 direction is not a matter of indifference, the contractions being always 

 unequal to the two directions of excitation : as a rule, but not always, the 

 more effective direction was from tibial to pelvic end, and this was therefore 

 taken as the ordinary direction of exciting currents. But this is not a very 

 essential point, all that is really necessary is to keep to one direction during 

 experiment. Unpolarisable electrodes are also unnecessary, as, indeed, may 

 be readily seen from the records obtained. The magnification of contraction 

 by the lever was x 2. 



(From October 9 onwards I used narrower muscle tubes, in order to use 

 up less fluid for each bath, and to have a greater density of current passing- 

 through the immersed muscle.) 



Alterations of current distribution caused by alterations of resistance of 

 the experimental fluids ; the oligodynamic action attributable to the use of 

 copper wire ; small differences of room temperature ; the possible excitation 

 of intramuscular nerve as well as of the muscle itself, are the principal 

 circumstances that have been considered and recognised to be negligible in 

 the present connection. On the other hand, every care has been taken to 

 secure constant strength of stimulation and constant pressure of the 

 myographic levers against the recording surfaces, which are moved past 

 the levers in tandem by the same clockwork. The influence of considerable 

 differences of temperature was specially examined {vide infra). 



By preliminary experiments it was found that conveniently graded effects 

 upon muscular excitability were produced by a 5 per 100 solution of alcohol, 

 by a 1 per 100 solution of ether, and by a 1 per 1000 solution of chloroform 

 (by volume in each case). These strengths are of the order of molecular 

 (5'8 c.e. per 100) in the case of alcohol, decimolecular (T03 per 100) in that 

 of ether, and centimolecular (0 - 8 per 1000) in that of chloroform. 



Thereafter solutions were made up on a molecular scale, taking as the 

 standard of reference a molecular solution of absolute alcohol, and as the 

 first terms of comparison a decimolecular solution of ether and a centi- 

 molecular solution of chloroform as tabulated below. 





Sp. gr. 



Mol. wfc. 



c.c. per 100 c.c. saline 

 to give molecular solutions. 





0"79 



46 



5-8 



Ether 



0-72 



74 



10 -3 





1 '50 



119 "5 



7-95 



