October 12, 1900.] 



SCIENCE. 



551 



part in it, and as ordinary nitroethane is 

 non-conducting, a body of different consti- 

 tution must be present, and tliis is regarded 

 as the true acid CH3.CE[=N0.0H ; tliis, 

 however, gradually loses its conductivity, 

 being transformed into common nitro- 

 ethane. Nitroethane is, therefore, capable 

 of existing in two forms, the ordinary form, 

 the stable pseudo-acid CHj.CHj.NO^, gradu- 

 ally metamorphosing under the action of an 

 alkali into the true acid CHj.CH^NO.OH, 

 which, stable as a salt, is labile in the free 

 condition, gradually passing back into the 

 pseudo-acid. In this, as in many other 

 cases studied by Hantzsch, we find an inti- 

 mate relation between tautomeric meta- 

 morphosis and ionization. Briihl has also 

 recently pointed out a relation between 

 tautomeric change and the nature of the 

 solvent in which it occurs, the change from 

 the enol to the keto form being promoted 

 by ionizing solvents like water and alcohol, 

 while non-ionizing solvents prevent or hin- 

 der it. 



Passing from isomers in which both forms 

 are stable, through various degrees of tau- 

 tomerism, to where one of them is too 

 labile to exist at all, at least under ordinary 

 conditions, we reach the state of affairs 

 prevailing among inorganic bodies. The 

 tautomeric organic bodies are an approxi- 

 mation to the inorganic ; their chemistry is 

 an approximation to inorganic chemistry. 

 Ostwald has recently suggested a division 

 of chemical compounds into two great 

 classes, the ionizing and non-ionizing.* 

 These would, in general, correspond to in- 

 organic and organic, but some of the in- 

 organic bodies would be found in the non- 

 ionizing groups, while besides the carboxylic 

 acids, a few organic compounds will be 

 found in the ionizing group. The tau- 

 tomeric compounds would occupy the inter- 

 mediate position. We learn from these 

 considerations one reason why inorganic 



*Grundriss der allgemeinen Chemie, 3" Aufl. S. 522. 



isomers are so seldom found. The labile 

 tautomer the more readily transforms into 

 the more stable form the higher the tem- 

 perature. The reason that we do not have 

 inorganic tautomers is simply because we 

 are working at too high a range of tem- 

 perature. Much below room temperature 

 we shall probably find a field of inorganic 

 tautomerism and isomerism as rich or 

 richer than that presented by organic 

 chemistry. There is no sharp line of de- 

 marcation between the two fields ; the ap- 

 parent difference results from the relatively 

 greater inertness of the carbon union. If 

 the methods of physical chemistry have 

 hitherto found most application in inorganic 

 chemistry, they are now being extended, in 

 organic chemistry, first of all to those com- 

 pounds which most closely resemble the in- 

 organic, namely, the tautomers. 



A word on the application of tautomerism 

 in physiological chemistry. The organic 

 constituents of protoplasm, in so far as 

 they are essentially active, are, on Loew's 

 theory, highly labile. The death of the pro- 

 toplasm is at once accompanied by the 

 transformation of its labile proteids into 

 their stable forms. What it is that pre- 

 vents this change taking place in life we do 

 not know, j'et it is evident that if we are to 

 get light on the subject from the chemical 

 side, it will not be so much by attempting 

 to synthesize dead proteids, as by studying 

 labile forms. I incline to the opinion, 

 therefore, that the study of the phenomena 

 of tautomerism is of the highest importance 

 for physiological chemistry, and that phys- 

 iological chemists will do well to turn their 

 attention to this field. 



It is usually assumed that no portion of 

 organic chemistry is further removed from 

 the inorganic than the study of the living 

 cell. I am inclined to hold the opposite 

 opinion. If, as I have suggested, the 

 labile tautomeric compounds lie between 

 the stable organic compounds on the one 



