94 Mr. S. U. Pickering on Mr. Lupton's Method of 



break in the density-curves which I mentioned as being "of a 

 very doubtful character;" and it is by a still stranger accident 

 that the only hydrate on which his investigation " seems to 

 throw very grave suspicion," is the very one which actually 

 does exist, which has been isolated in the crystalline con- 

 dition (Chem. Soc. Trans. 1890, p. 339). and to the isolation 

 of which I was led by a reliance on the very method which 

 Mr. Lupton considers to be fallacious and worthless. 



45 



50 



55 



60 



65 



70 



75 





H 2 . S0 4 



PER CENT 





' 



/ 



7 



,'V 



/ 









'#■ 



yy 



/ 











/ 



• 









• 



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• 



7 











t / 



H 













■0120 



cte 

 dp 



•0115 

 0110 

 01 05 

 0100 

 0095 



A.B. Direct first differential of the experimental points, and Pickering's 



representation of them. 

 CD. First differential of Lupton's calculated values. 



So much for Mr. Lupton's main argument ; it remains but 

 to answer the minor objections which he raises. 



1. Mr. Lupton (p. 420) is " astonished " to find that I give 

 the composition of the solutions to the fifth decimal place ; 

 but, as the relative composition of these solutions was correct 

 to one unit in the fourth place (loc. cit. p. 73), I was only 

 following precedent in so doing ; surely Mr. Lupton would 



