INFLUENCE OF PROPORTIONS IN ELECTROLYTES. 83 



with Strong sulphuric acid, was found to conduct and decompose slowly. But on 

 examination there were strong reasons for believing that water was present, and that 

 the decomposition and conduction depended upon it. I endeavoured to prepare a 

 perfectly anhydrous portion, but could not spare the time required to procure an un- 

 exceptionable result. 



685. Nitric acid is a substance which I believe is not decomposed directly by 

 the electric current. As I want the facts in illustration of the distinction existing 

 between primary and secondary decomposition, I will merely refer to them in this 

 place (7o2.). 



r.86. That these mineral acids should confer facility of conduction and decompo- 

 sition on water, is no proof that they are competent to favour and suffer these ac- 

 tions in themselves. Boracic acid does the same thing, though not decomposable. 

 M. De la Rive has pointed out that chlorine has this power also ; but being to us an 

 elementary substance, it cannot be due to its capability of suffering decomposition. 



687. Chloride of sulphur does not conduct, nor is it decomposed. It consists of 

 single proportionals of its elements, but is not on that account an exception to the 

 rule (679.), which does not affirm that all compounds of single proportionals of ele- 

 ments are decomposable, but that such as are decomposable are so constituted. 



688. Protochloride of phosphorus does not conduct nor become decomposed. 



689. Protochloride of carbon does not conduct nor suffer decomposition. In asso- 

 ciation with this substance, I submitted the hydro-chloride of carbon from olefiant gas 

 and chlorine to the action of the electric current ; but it also refused to conduct or 

 yield up its elements. 



690. With regard to the exceptions (679.), upon closer examination, some of them 

 disappear. Chloride of antimony (a compound of one proportional of antimony and one 

 and a half of chlorine) of recent preparation was put into a tube (fig. 13.) (789.), and 

 submitted when fused to the action of the current, the positive electrode being of plum- 

 bago. No electricity passed, and no appearance of decomposition was visible at first ; 

 but when the positive and negative electrodes were brought very near each other in 

 the chloride, then a feeble action occurred and a feeble current passed. The effect 

 altogether was so small (although quite amenable to the law before given), and so 

 unlike the decomposition and conduction occurring in all the other cases, that I 

 attribute it to the presence of a minute quantity of water, (for which this and many 

 other chlorides have strong attractions, producing hydrated chlorides,) or perhaps of 

 a true protochloride consisting of single proportionals (695. 796.). 



691. Periodide of mercury being examined in the same manner, was found most 

 distinctly to insulate whilst solid, but conduct when fluid, according to the law of 

 liquido' conduction (402.) ; but there was no appearance of decomposition. No iodine 

 appeared at the anode, nor mercury or other substance at the cathode. The case is, 

 therefore, no exception to the rule, that only compounds of single proportionals are 

 decomposable ; but it is an exception, and I think the only one, to the statement, that 



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