176 Mr. V. H. Veley on the Phases and 



explanation of the commencement of chemical change but 

 also as being supported by evidence derived from a study of 

 other physical phenomena *, that it would seem to savour 

 almost of ultra-conservatism f to pass any criticism upon it. 



On all sides it is admitted that if the hypothesis of ionic 

 dissociation be granted other phenomena would follow as 

 logical consequences ; and of these no other explanation has 

 been given, though they are not wholly otherwise unintel- 

 ligible. But the proponnders of this theory seem at best to 

 slur over the initial difficulties, and to postulate properties of 

 certain kinds of matter of which, ex hypothesis we can have 

 no cognition. 



To take the more commonly selected example : it is sup- 

 posed that when potassium chloride is dissolved in excess of 

 water it is more or less dissociated into free potassium and 

 free chlorine atoms, each with enormous electric charges, equal 

 and opposite in kind. It is further assumed J that the free 

 potassium ions are a kind of matter different from a lump of 

 potassium, and that the free chlorine ions are a kind of matter 

 different from chlorine gas in a jar, somewhat as yellow and 

 red phosphorus are different kinds of matter. Writers allow 

 that there is no exact knowledge of the amount of these 

 electric charges, and, indeed, if according to the hypothesis 

 these are equal and opposite in kind, there seems to be some 

 difficulty in devising any experimental method for their mea- 

 surement. But they consider that it is a matter of acquired 

 knowledge that the chemical and physical properties of ele- 

 mentary substances are greatly altered and almost nullified 

 by electric charges imparted to them by the mere process of 

 solution of their compounds in water. A lump of potassium 

 is regarded by this school of writers as made up " of mole- 



* For a review of the position cf. Arrhenius, " Chemical Theory of 

 Electrolytes," Acad. Science, Sweden ; also W. N. Shaw, B. A. Report, 

 1891, who gives the references to the literature upon the subject. 



t One can hardly refrain from quoting the following passage from 

 Nernst's work Theoretische Chemie (Stuttgart, 1893), as an example 

 of self-satisfactory dogmatism almost unequalled in any scientific publi- 

 cation : — " Es ist hier natiirlich nicht der Ort, auf den Inhalt einer der- 

 artigen unfruchtbaren Opposition, die auch nicht ein einziges neues 

 Moment zu Tage forderte, imd die daher am besten einer schnellen Ver- 

 gessenheit anheimfiele, naher einzugehen." 



% Writers upon this subject seem almost to consider that no assumption 

 is here implied ; thus Ostwald (Zehrbuch der allgemeinen Chemie, Leipzig, 

 1893, p. 784) writes : — " Die Aufklarung des scheinbaren Widerspruches 

 liegt so viel darin, dass ' freies Kaliummetall ' mid ' freie Kaliumionen' 

 ganz verschiedene Dinge sind ; sie sind nicht identisch, sondern rmr 

 isomer." This last sentence would imply a definite statement of fact. 



