On the Constitution oj aqueous Ammonia. 193 



the compound, beyond the volume of the constituents of the so- 

 lution. Or the specific gravity of the saturated solution is lesSy 

 than the mean sp, gr. of the salt and water. I know of no salts, 

 with which this phaenomenon occurs, except the ammoniacal. 



From the above experiments we may infer, that when Mr. 

 Dalton affirmed that the progressive dilutions of water of am- 

 monia are effected without changing the mean volume or den- 

 sity of the compound, he had been led into the mistake, pro- 

 bably by the imperfection of his instruments for taking specific 

 gravity. 



In endeavouring to ascertain the quantity of real ammonia in 

 the aqueous compounds, I took the most diluted of the above- 

 waters, to prevent the chance of any ammonia being exhaled 

 during the experiments. 



(1). 100 grains of the ammoniacal water, sp.gr. 0*9713, con- 

 taining 25 grains of the strongest, required for neutralization, 

 of dilute sulphuric acid, a quantity equivalent to 17*7 grains of 

 distilled and thoroughly concentrated oil of vitriol. Hence we 

 have this proportion in the svstem oi prime equivalents, 



6-125 : 2-125 : : 17*7 : 6-14, which number multipHed by 4, 

 gives 24-56, for the real ammonia, in 100 by weight of the 

 strongest water. 



After careful evaporation in a platina capsule, 24*3 grains of sul- 

 phate of ammonia were obtained. My former researches on the 

 ammoniacal salts, published in 1S17, showed that this desiccated 

 salt retained one prime equivalent of water. Hence we say 



S-25 : 2-125 : : 24-3 : 6-25, which multiplied by 4, gives 25 

 for the grains of ammonia in 100 of the water at 0900. 



(2). 100 grains of the water of 0*9713 were saturated with 

 a quantity of dilute muriatic acid, equivalent, by my table in the 

 Dictionary, to 13*5 grains of chlorine ; and yielded after cautious 

 evaporation, in a platina capsule, 20*3 grains of dry sal ammo- 

 niac. From the saturation experiment, we have this propor- 

 tion : 



4-5 : 2-125 : : 13*5 : 6*375, which multiplied by 4, gives 25*5 

 for the ammonia in 100 gr. of the water of 0*900. From the 

 saline product we obtain this proportion : 



6*75 *. 2* 125 : : 20*3 : 6*39 j and 639 X 4=25-56= the am- 

 monia in 100 of the water of 0*900. 



(3). 100 grains of the same dilute ammonia, being saturated 

 with nitric acid, yielded 2S*7 f^rains of dry nitrate. But 1 have 

 formerly shown that the desiccated nitrate retains a prime equi- 

 valent of water. Hence 



lO(=6-75-|-2-125-f 1-125): 2-125:: 28-7: 6-1; and 6-1 x 

 4 = 24*4, a quantity somewhat less than the preceding results, as 



Vol. 57. No. 275. Marck 1821. B b might 



