450 Prof. Schonbein on the Connexion of 



can change any quantity of peroxide of hydrogen into water and 

 common oxygen by means of the smallest quantity of gold. 



It appears to me as if the actual facts of the phsenomena of 

 fermentation were by no means so accurately known as ought to 

 be the case, to enable us to decide with certainty whether the 

 chemical state of decomposition of the yeast, as such, exercises a 

 determinate influence on the fermentation of the sugar or not. 



If, as I am inclined to think, the transference of the chemical 

 activity of one substance to another in the above-mentioned cases 

 is only apparent, that is, mediate, we may consider it possible 

 that the relation of the decomposition of the sugar to that of the 

 yeast is not one of effect to cause ; the latter decomposition is 

 only concurrent with the former, and is not a phsenomenon in- 

 ducing the saccharine fermentation. 



In what, then, is the obvious action of the yeast to be sought ? 

 I do not conceal, that to me our present knowledge of the funda- 

 mental phsenomena of chemistry appears so imperfect, that I must 

 deny to it the capability of solving the enigma of even the most 

 proximate cause of fermentation ; and in my opinion it is of more 

 advantage to science to consider a phsenomenon as still unex- 

 plained, than to assign to it a false cause ; because the former 

 excites to further inquiry, the latter retards or even puts an end 

 to it. 



We are certainly justified in considering as possible causes 

 those still unexplained facts which we meet with in the pha;no- 

 mena of fermentation ; and making use of this liberty, I will 

 seek finally to indicate a possible reason for the activity of 

 ferments. 



I have adduced, in this and in other papers, facts which 

 appear to me to show that a series of chemical actions, both 

 analytical and synthetical in their nature, are caused by the allo- 

 tropizing influence which certain substances exert upon oxygen. 

 It is possible that the efiicacy of the yeast might be due to an 

 allotropizing influence which it exerts on one or the other of the 

 constituents of sugar ; and I will endeavour to explain this idea 

 by adducing the various decompositions of which an inorganic 

 compound, iodate of potash, is capable. 



This salt decomposes, when sufficiently heated, into iodide of 

 potassium and common oxygen ; intimately mixed with graphite 

 or peroxide of manganese, it decomposes into free iodine, oxygen 

 and potash, at a lower temperature than that at which the salt 

 alone decomposes in the manner stated. 



As I have already remarked, the immediate I'eason of the last 

 mode of decomposition of the iodate lies, in my opinion, in the 

 deozonizing influence which peroxide of manganese, &c. exerts 

 upon the of iodic acid at a temperature which is far below 



