488 



Prof. W. A. Douglas Ruclge on the 



Sulphides gave very strongly charged clouds, which were 

 generally positive. 



Table VII. 



Sulphide. 



Charge. 



Sulphide. 



Charge. 



Antimony, Red 



+ 

 + 



4- 



Mercuric Black 



+ 



+ 



+ 



Antimony, Black 



Mercuric Bed 



Bari urn 



Botassium 



Calcium 



Tin 



Copper 



Zinc 



Iron 







Reasoning by analogy with the carbonates, we might have 

 expected sulphides to give negative charges, because hydro- 

 sulphuric is a weak acid in solution, but sulphides are very 

 stable compounds, so that perhaps in combination the acid 

 is strong. 



Sulphates show considerable variation, but an isomorphous 

 group produced the same charge. Gypsum, CaSOJSE^O, gives 

 a positive charge, but after the water of crystallization was 

 driven off by heating, the anhydrous sulphate gave a nega- 

 tively charged cloud. 



The alkaloids are a well-known group of basic bodies, and 

 all give strong charges when blown into clouds. With these 

 were studied some allied bodies, and the results obtained are 

 shown in Table VIII. 



Table VIII. 



Substance. 



Charge. 



Substance. 



Charge. ' 



Aconitine 



1 1 1 1 ! + 1 1 1 



Morphine chloride 



Atropine 



' Quinine 



— 



Brucine 



Quinine sulphate 



Caffeine 



Strychnine 



_ 



Cantharidine 



, Salicin 



+ 



Cinchonine 



1 Theine 



+ 



Cocaine .... 



+ 



Codeine 







Morphine 





+ | 







It is very remarkable that all those alkaloids which are of 

 more or less similar constitution should give negative charges, 

 whilst morphine chloride behaves as other chlorides and 

 gives a positive charge. Theine and caffeine are undoubtedly 

 the same substance, and although classed with the alkaloids 



