Mr. Griffin on the Constitution Wf^oyjf&olut£ns. 289 



strewed over the bottom of the pan^^j|gj|ffifdmrith care 

 for about a fortnight. 



The great advantage of this compound is, that it may be 

 used continuously for a fortnight without renewal; and, unlike 

 bromine water, its action is unaffected by the ordinary changes 

 of temperature. 



I have hastened to communicate this during the present fine 

 weather, believing that it will be acceptable to all interested 

 in this beautiful application of science. 

 September 14, 1846. 



XLVI. On the Constitution of Aqueous Solutions of Acids and 



Alkalies. By John Joseph Griffin, Esq.* 

 A N inquiry has been instituted of late into the volume that 

 ^"*- is assumed by a given weight of any chemical substance 

 on being dissolved in water ; and the chemists who have in- 

 stituted this inquiry have promptly drawn conclusions and 

 established laws, very general and comprehensive in character, 

 and susceptible of important applications, provided they are 

 founded on* well-established facts. 



Thus, "in the year 1840," I quote from Messrs. Playfair 

 and Joule, " Dalton made the interesting discovery, that 

 sugar and certain salts on being dissolved in water increase 

 its bulk only by the amount of water pre-existing in them. 

 He generalized this observation by asserting that all hydrated 

 salts dissolve in water, increasing its bulk merely by their 

 amount of water of hydration, while anhydrous salts do not 

 at all increase the bulk of the water in which they are dis- 

 solved. 



" But it must not be forgotten, that when Dalton published 

 this paper he was much enfeebled by illness, and on this ac- 

 count it does not derogate from the acuteness of the philoso- 

 pher, that Mr. Holker was unable to confirm Dalton's results 

 in repeating the experiments in 1843. He did so however in 

 the case of sulphate of magnesia, and approximately in that 

 of one or two other salts." — Philosophical Magazine, vol. 

 xxvii. p. 456. 



The experiments that were particularly described by Dal- 

 ton, were made with sugar and sulphate of magnesia. But he 

 declares that his hypothesis was not founded on those expe- 

 riments alone. He says, " I have tried the carbonates, the 

 sulphates, the nitrates, the muriates or chlorides, the phos- 



• Communicated by the Chemical Society ; having been read April 20, 

 1846 



