448 



SCIENCE. 



[N. S. Vol. XI. No. 273. 



Substances which in other conditions react 

 upon each other with the greatest energy 

 were perfectly indifferent. Thus the dan- 

 gerous phosphorus, which generally takes 

 fire in the air at a temperature somewhat 

 lower than that of the bodj', can be distilled 

 in oxygen ; and hydrochloric acid and am- 

 monia gas can be mixed without indica- 

 ting any reaction. How shall we reconcile 

 these observations with our commonly ac- 

 cepted theories ? Is there here an interval 

 in the properties, and is this interval con- 

 nected with a similar interval in the condi- 

 tions ; that is, have affinity and moisture 

 here in fact become absolutely nil? It is 

 indeed hardly necessary to assume that the 

 afiBnity has become zero, for one can equally 

 well account for the phenomena, if one as- 

 sumes that the velocity of the reaction has 

 diminished very greatly, as seems already 

 to have been proved the case at very low 

 temperatures and for a perfectly dry mix- 

 ture of carbon monoxid and oxygen. Also 

 against the assumption that in Baker's ex- 

 periment the last molecule of water has 

 been wholly removed may be cited the fact 

 that the water which is contained in the 

 metaphosphoric acid still possesses an ex- 

 tremely small vapor tension. Further, 

 even if Baker's dried gases really undergo 

 a sudden change in their chemical proper- 

 ties, it does not necessarily follow that at 

 the same time a sudden change in the 

 m^oisture shall be present. As a matter of 

 fact, we know that the properties of matter 

 often change in a very unexpected way 

 when they are only in the vicinity of such 

 a limiting condition. The electrical phe- 

 nomena in tubes of high vacuum present a 

 familiar example. From a theoretical 

 standpoint the facts which have been men- 

 tioned, aside from the interest which they 

 arouse from their strangeness, are also re- 

 markable on another ground. This has 

 reference to the different hypotheses which 

 have been proposed as the cause of reac- 



tions. Among these we may note that of 

 Armstrong, who assumes the presence of 

 free atoms or ions and looks upon the con- 

 ditions of reaction in gases, practically in 

 a similar way to that demanded by the 

 theory of Arrhenius and Ostwald for liquid 

 electrolytes. By this the analogy which 

 has been suggested between these two 

 states of aggregation, and which at present 

 dominates the thought in the province of 

 inorganic chemistry, is rendered complete 

 We may add to this that the remarka- 

 ble observations, according to which gases 

 under the influence of Eontgen and certain 

 other rays become conductors just as if 

 electrolytes, lead to the same conclusion. 

 It shows us again in what close relationsliip 

 the perfection of methods and of the ex- 

 perimental resources on the one side, and 

 advancement in knowledge on the other, 

 stand to each other. Experimental science 

 and theory are a constant stimulus to each 

 other and bring forth their fruit side by 

 side. 



And now I have come to the end of my 

 proposed task. I have indeed spoken only 

 from the standpoint of my own field ; but 

 I believe that the conclusions which are 

 drawn from these considerations may be 

 so far generalized that they appear of im- 

 portance for the technologist also. The 

 sciences on which his work rests are ap- 

 plied mathematics and applied natural 

 science. The former can do its work wher- 

 ever the latter has by experiment laid a 

 foundation, and because thus in the im- 

 provement of methods and appliances re- 

 sults are being attained which are of in- 

 creasing value, the technologist may take 

 an interest, we may almost say an egotistic 

 interest, in the successful development of 

 the pure natural sciences. One thing fur- 

 ther, of a mora ethical nature may be sug- 

 gested by the fundamental similarity of the 

 problems in both departments. Just as we 

 chemists labor to come as close as possible 



