Catalytic Phaenomena with Allotropy. 447 



drogen into water and oxygen precisely because they convert the 



of this compound into 0, it is also possible that the catalytic 

 decomposition of persulphide of hydrogen into HS and S depends 

 on an allotropizing influence which certain substances exert upon 

 sulphur. 



Every chemist knows that this substance can be allotropized, 

 but we are not able to say in what condition the persulphide of 

 hydrogen contains its S. It may be possible that four equiva- 

 lents of sulphur in this compound exist in an allotropic condition, 

 which is different to that in which this element exists in sulphur- 

 etted hydrogen. And were this the case^ it is easily seen that 

 these four equivalents of sulphur could only i-emain combined 

 with the HS as long as they continued in their peculiar con- 

 dition, but that they would separate from their compound as 

 soon^as they ^underwent an allotropic change, as happens with 

 the O of HO + when it is converted into 0. 



We have already become acquainted with a number of ele- 

 mentary substances which are capable of assuming allotropic 

 conditions, and it may therefore be presumed that the other 

 simple substances also are capable of allotropy. It is also ex- 

 ceedingly probable, if not certain, that one and the same element 

 can exist in its various allotropic modifications, not only when 

 free, but also when combined. It is therefore not difficult to per- 

 ceive of what importance to science allotropy must prove, when 

 we have once ascertained the influence which the allotropic con- 

 ditions of an element exert upon its chemical comportment. A 

 large number of chemical combinations and decompositions, 

 caused by imponderable or ponderable agents, might then be 

 considered as actions immediately produced by allotropic modi- 

 fications of the elementary substances concerned. 



In a paper which I published some years ago, " On the Che- 

 mical Actions of Electricity, of Light, and of Heat," I endea- 

 voured to show that in many cases they most probably consist 

 in allotropizing influences which these agents exert upon oxygen ; 

 and as I have found no reason to alter those views, but, on 

 the contrary, have shice ascertained some new facts which must 

 strengthen them still more, I will here merely refer my chemical 

 readers to that paper. 



I must also mention a phsenomenon which may have some 

 connexion with the facts just adduced, but which, in my opinion, 

 is at present one of the most obscure phsenomena of chemistry, 



1 mean fermentation. In the present state of chemical know- 

 ledge, who would venture to say, for example, why sugar under 

 certain circumstances decomposes into alcohol and carbonic acid. 

 The most essential conditions which are necessary in order that 

 fermentation may take place, are certainly known ; but the part 



