IOWA ACADEMY OF SCIENCES. H 



absorbed by potash, a resiiUie of about 3 c. c. being left. This residue con- 

 sisted essentially of hydrogen. 



The chain of evidence now appeared complete, for unless there were two 

 kinds of nascent hydrogen it would be all oxidized in both cases if in either. 

 the conditions l)eing the same, and the fact that none was found in the cop- 

 per experiment must be taken for valid proof that none was formed. 



In reality the correct view would appear to be that at the temperature of 

 the reaction the acid is for the greater part dissociated into HjO and SO3, the 

 copper being oxidized by the latter only. The zinc acts upon the SO3 form- 

 ing SO.^, and also upon the undissociated part of the acid, setting free hydro- 

 gen which escapes. 



Further light may be thrown upon this matter by a consideration of the 

 reduction of the sulphuric acid by carbon. This reaction takes place at 

 about the same temperature as that with copper, in accordance with the 

 equation 



C+2H, SO,=2Hj04-C02+2S02 [11 



Here there can be no question of nascent hydrogen unless by assuming 

 the existence of a sulphate of carbon, thus 



C+2H2SO^=C(SOj2+4H |12 



which is wholly unwarranted, and thei'e is no ground for supposing the 

 mechanism of the action of carbon on sulphuric acid to be entirely difl'erent 

 from that of copper on the same compound. 



A favorite field in which nascent hydrogen often disports itself lies in the 

 extremely complex reactions between nitric acid on the one hand and vari- 

 ous metals on the other. Here the nitric acid may be reduced to ammonia, 

 hydroxylamine, free nitrogen, nitrous acid, any of the oxides of nitrogen, 

 and possibly still other products. Often many of them are simultaneously 

 formed. Of these, ammonia and laughing gas and N2 ai-e never formed by 

 the action of mercury, Bi., Cu. and Ag.^ Iron, on the other hand, may 

 reduce the whole of the nitric acid to ammonia. Montemartini, who has 

 made a special study of this group of reactions", and others have shown that 

 the various metals reduce nitric acid in various ways, giving reaction pro- 

 ducts in different proportions and of different kinds. The bearing of this 

 upon the subject of the present paper is evident. If, for example, iron, 

 zinc and copper all reduce nitric acid indirectly through the primary forma- 

 tion of nascent hydrogen, we would expect the ultimate products to be the 

 same in kind and in relative amount, the absolute amount depending sim- 

 ply upon the quantity of hydrogen formed. Since this is not so, the conclu- 

 sion is inevitable that the nascent hydrogen is not the reducing agent but 

 the action of each metal is immediate and specific, removing oxygen from 

 the acid and forming unstable intei-mediate products which elude direct 

 observation but which, by their reactions, give rise to the products charac- 

 teristic of each case. 



I have endeavored, in this discussion, to select the fairest instances of 

 the application of the nascent condition hypothesis and find myself forced 

 to the conclusion that it is the survival of an obsolete doctrine; that it 

 explains nothing which cannot be as well or better explained without it; 

 that it cannot be reconciled in certain cases with known facts, and that. 



1 Bo: 92, 616, 898 f . 

 21,0c. cit. 



