Dissociation of Compounds in Water. 497 



results by the former method for the acids and alkalies 

 are slightly lower than by the latter, but I think that 

 this has been fairly satisfactorily explained. The slight 

 difference for the carbonates can be accounted for by hydro- 

 lysis. The freezing-point method, as here improved, is 

 probably as accurate a measure of dissociation as the con- 

 ductivity method for all those dilutions, except the most 

 dilute to which it has been applied. The lowering of the 

 freezing-point produced by the most dilute solutions is so 

 small that the error of measurement is necessarily relatively 

 great. 



The organic compounds which do not undergo electrolytic 

 dissociation have all given more or less unexpected results. 

 The molecular lowering for the most dilute solutions is much 

 greater than the constant for water. As the concentration 

 is increased the molecular lowering decreases to a mini- 

 mum, and then either remains constant or, as with the two 

 carbohydrates, increases. The minimum for phenol was, 

 apparently, not reached. The dissociation of acetic acid, 

 as calculated from the freezing-point, agrees moderately 

 well with that from conductivity, but for succinic acid the 

 freezing-point results are considerably higher. The con- 

 stant for water, which I have found from urea and ethyl 

 and propyl alcohols, agrees very closely with that calculated 

 by van't Hoff. 



I hope to apply this method in the future to a large number 

 of more complicated inorganic compounds, for the purpose of 

 measuring their dissociation in water and other solvents ; 

 also to a much larger number of organic compounds and 

 classes of compounds, to determine whether the peculiarities 

 presented by those already examined are of a general 

 character. This method can also, apparently, be used to 

 measure the dissociation of organic acids. 



In conclusion, I wish to express my thanks to Prof. 

 Ostwald, in whose laboratory this work has been carried out 

 and to whom I am indebted for many valuable suggestions 

 during its progress. 



Leipzig, Phys. Chemical Laboratory, 

 September 1893. 



Phil. Mag. S. 5. Vol. 36. No, 223. Dec. 1S93, 2 L 



