Aqueous Solutions of Acids and Alkalies. 459 



The approximate coincidence of my experiments with Dr. 

 Ure's will perhaps be held to prove the correctness of his 

 opinion ; and I must admit that there is some appearance of 

 the occurrence of a slight expansion at about 300°. Yet this 

 apparent expansion is so small, and the figures that indicate 

 it are so likely to be merely the expression of errors of ex- 

 periment, that I consider the expansion, though possible, not 

 by any means proved. The evidence tending to prove that 

 ammonia has a fixed atomic volume in solution, seems to me 

 greatly to preponderate over that which indicates expansion. 

 My doubts respecting the occurrence of expansion were fur- 

 ther strengthened by the results of the following experi- 

 ment. 



Into a long narrow graduated bottle I put 500 septems of 

 strong commercial ammonia, the degree of which was 810°. Its 

 specific gravity was 0*898572 by trial. By means of a bottle 

 so graduated as to deliver 500 septems of water, I added that 

 quantity to the ammonia. The bottle was stopped, wrapped 

 in a thick towel, and briskly shaken for about a minute. 

 Each liquor previous to the mixture was brought to the 

 temperature of 51° F. Immediately after the shaking, the 

 temperature was found to be 54° F. Here was a rise of 3°, 

 indicating, not expansion, but condensation. When the li- 

 quor had returned to 51° F. its volume was examined. There 

 certainly was no expansion. I think there was a slight con- 

 densation, but it was scarcely measurable. The chemical 

 strength of the diluted liquor was found to be 406°. This 

 indicated condensation. Its specific gravity was '950600, 

 and since (-898572 + \)\+ 2 = -949286, this also indicated 

 condensation. 



The results which in this experiment indicate condensation 

 are, I believe, as remote from the truth as those which in 

 other experiments seemed to indicate expansion. One of these 

 results is remarkable, namely, the rise in temperature which 

 apparently results from the combination of the two liquids. 

 If water and liquid ammonia combine without change of vo- 

 lume, there should be no change of temperature. To what 

 cause then shall we attribute the rise of 3° F. ? To agitation 

 alone ? That, I think, is sufficient to account for it. 



I cleaned the bottle from ammonia, put into it a deci- 

 gallon of distilled water, and shook it for one minute. The 

 temperature rose from 49° to 49^° F. Half a gallon of water 

 shaken in a larger bottle rose from 43|° to 44^°. 3000 sep- 

 tems rose from 49|-° to 50^°. A solution of pure carbonate 

 of potash rose from 50£° to 51£°. A solution of pearlash 



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