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tion. The union of biatomic radicals of the hydrogen-group with 

 molecules of the oxygen-group gives rise to combinations of a far 

 more complicated character. Whilst one molecule of water, H 2 O 2 , 

 most conveniently may be considered as the type of many compounds 

 of the former class, the corresponding compounds of biatomic radicals 

 frequently correspond to a double molecule of water, 2H 2 O 2 . 



Sulphocyanide of potassium may be viewed as water, in which the 

 oxygen is replaced by sulphur, one of the hydrogen molecules by 

 cyanogen, the other by potassium. 



Water ^ j O 2 Sulphocyanide of potassium ^ j S 2 



In the production of Sulphocyanide of ethylene two equivalents of 

 chlorine in chloride of ethylene (C 4 H 4 C1 2 ) have to be eliminated by 

 two equivalents of potassium. Thus the very reaction of the two 

 factors, chloride of ethylene (C 4 H 4 C1 2 ), and two equivalents of Sul- 

 phocyanide of potassium 2(K Cy S 2 ), joins 4 equivs. of sulphur and 

 2 equivs. of cyanogen with one molecule of ethylene. This reaction 

 may be expressed by the following equation, which will illustrate at 

 once my view in regard of the constitution of this substance : 



+ C 4 H 4 C1 2 =C 4 H 4 +2KCL 



Cy J S * 



The acid produced by the action of nitric acid upon Sulphocyanide 

 of ethylene obviously belongs to the same type. In this compound, 

 which in the conception of this view may be called ethylene-sulphurous 

 acid, the cyanogen is replaced by hydrogen, whilst the sulphur has 

 been oxidized into the compound radical S 2 O 6 , which in sulphurous 

 acid we assume united with hydrogen. 



Two H 1 n Two equivs. H \ n Ethylene- H 1 Q n 



mole- H / U * of bisulphite K / ^ u e sulphu . }*>* e- 



cules of H 1 n of potas- H 1 ft rous 4 4 1 Q n 



water. H / sium. K / S * 6 acid. H / S * " 



Since we find that the hydrogen-molecules in polybasic acids are 

 replaceable by two or more molecules of different metals or radicals, 

 witness tartrate of potassium and sodium, oxalovinate of potassium, 

 the idea naturally suggests itself that the biatomic alcohol-forming 

 radicals may be capable of uniting two molecules of different elements 



