192 On Ihe Constitution ofatjueous Ammonia. 



tions of the same nature indeed as those which constitute our 

 ordinary sounds, but so remote, that the animals who perceive 

 them may be said to possess another sense, agreeing with our 

 own solely in the medium by which it is excited, and possibly 

 wholly unaffected by those slower vibrations of which we are 

 sensible. 



I should be always most unwilling to occupy the time of this 

 Society vvith idle speculations on mere possible modes of exist- 

 ence, and should not have called its attention to this subject, 

 had I not observed several curious facts which I thought might 

 prove interesting, and may serve to justify some latitude of con- 

 jecture beyond the strict evidence of our senses. 



XXX. On the Constilution of aqueous Ammonia, iJy Andrew 

 Ure, M.D. Professor of the Andersonian Institution, &c. 



In the article Ammonia of the Dictionary of Chemistry, lately 

 published, after giving the valuable table of Sir H. Davy, I have 

 said, " Probably the quantity of ammonia stated in the above 

 table is too high by about 1 per cent." This remark was ha- 

 zarded in consequence of some results which I obtained, in a 

 train of experiments which I instituted four years ago, with the 

 view of constructing new tables of the aqueous solutions of the 

 alkalies, earths, and most important neutral salts. 



The diflference between Mr. Dalton's table of aqueous am- 

 monia, adopted by Dr. Thomson in the last two editions of his 

 System, and the tables of Sir H. Davy and my own, induced me 

 lately to perform the following experiments, the results of which 

 will, I hope, prove acceptable to practical chemists. 



1 impregnated distilled water with pure ammoniacal gas, till 

 its specific gravity at 60° was found to be exactly 0'900. 500 

 grains of this, mixed with 500 grains of distilled water, and 

 agitated in a close phial, gave, after a proper interval to ensure 

 intimate combination, a specific gravity at i»0" F. of 0'9455() 

 While the mem sp. gr. of the components is . . . . 0'94737 



500 grains of this diluted water of ammonia being combined 

 with 500 grains of distilled water, formed a compound having a 

 specific gravity of .. .. .. .. .. 0-97130 



While the njcan sp. gr. of the components is . . . . 97297 



Hence we see that the remarkable expansiveness, which am- 

 monia carries into its first condensation with water, continues 

 in the subsequent dilutions of its aqueous combinations. This 

 curious property is not peculiar to pure ammonia, but belongs, 

 I have found, to some of its salts. Thus sal ammoniac, by its 

 union with water, causes aa enlargement of the total volume of 



the. 



