1276 



In order to obtain normal results it is necessary to earth the 

 sprayer. The amount of positive or negative charge present where 

 the screen has been placed, may be largely affected by admixing 

 cane-sugar or sodium chloride to the solution to be sprayed. 



By the admixture of cane-sugar the charge on the screen is always 

 raised, with the antipyretica extinction never occurs. The admixture 

 of sugar is indifferent in the case of solutions of mesotan, tussol, 

 and aiitifehrin. it goes without saying that in the like experiments 

 due care should be taken that the sugar be perfectly pure, since 

 an old sugar-solution is of itself electrifying. 



The substances evolved under the circumstances can be removed 

 from it only by filtration through animal charcoal (not so easily 

 through extraction with absolute alcohol and subsequent cautious 

 evaporation of the alcohol from the purified sugar left after filtration). 



The effect of an admixture of sodium chloride is quite different. 

 The concentration in which it takes place is of the greatest influ- 

 ence, as appears from the following table: 



Factor of decreasing the charge of salicyUc acid and saUcylas natricus 

 through various NaCl-concentrations. 



NaClsol. (cone.) 



Salicylas Na. 0.00125n. SalicyHc acid 0.00125n 



Seeing that even traces of sodium chloride modify the charge, it is 

 essential to make certain beforehand that suitable water be used 

 for solution. Distilled water cannot be recommended, since after 

 standing for some days in a well rinsed bottle, it obtains of itself 

 electrifying power (analogon of the old sugar solution). By shaking 

 it for a considerable time with pure animal charcoal and by sub- 

 sequently filtering it, distilled water can also be liberated from the 

 electrifying admixture, which is volatile, for suction of air removes 

 it in part at least. 



The tapwater of the Utrecht Water Company being nearly free from 



