CHAP. X. §. I. DUBING MUSCULAE OONTBACTION. 115 



It was found necessary that the following pre- 

 cautions should he strictly attended to. The solutions 

 should he prepared and well mixed previous to their 

 use, and the electrodes covered to the same extent. 

 The hands and fingers should he thoroughly clean; 

 to attain this object, they were first washed with the 

 ordinsiry curd or Windsor soap, and afterwards well 

 rinsed in common water, and wiped comparatively 

 dry with a clean towel. The same towels should 

 not be employed when using the difierent solutions, 

 and it was found better to work on different days 

 with each solution ; for the liquids soaking in 

 between the nails and the fingers became a source 

 of some difficulty to remove, and a cause of some 

 embarrassment in judging of the final result. 



It need hardly he stated, that the surfaces of the 

 electrodes should be clean and the contacts perfect. 



With the solution of common salt. Upon the first 

 introduction of the fingers, a slight tremulous motion 

 of the needle occurred. Withdrawing the right-hand 

 fingers and reintroducing them immediately after- 

 wards, and repeating this act a few times, a slight 

 positive effect was produced upon the introduction of 

 the fingers. Withdrawing the left-hand fingers in 

 the same manner, a slight negative effect was at first 

 obtained, hut after a short time the effect became 

 indefinite, and ultimately slightly positive. Keeping 

 the fingers in and contracting the muscles of the 

 arm, the fingers of the contracted arm were positive 

 4° to 5°, and made to increase. 



