On the Decomposition and Composition of the Alkalis. 147 



very pure ammoniacal gas*; a great expansion of the aeri- 

 form matter took place, and a white substance formed, 

 which collected on the sides of the glass tube employed in 

 the process ; and this matter, exposed to the action of di- 

 luted muriatic acid, effervesced, so that it was probably car- 

 bonate of ammonia. 



A process of another kind offered still more decisive re- 

 sults. In this the two mercurial gasometers of the invention 

 of Mr. Pepys, described in No. XIV. of the Phil. Trans, 

 for 1807 t, were used with the same apparatus as that em- 

 ployed by Messrs. Allen and Pepys for the combustion of 

 the diamond, and these gentlemen kindly assisted in the ex- 

 periment. 



Very pure ammoniacal gas was passed over iron wire ig- 

 nited in a platina tube, and two curved glass tubes were so 

 arranged as to be inserted into a freezing mixture ; and. 

 through one of these tubes the gas entered into the platina 

 tube, and through the other, it passed from the platina tube 

 into the airholder arranged for its reception. 



The temperature of the atmosphere was 55°; but it was 

 observed that no sensible quantity of water was deposited in 

 the cooled glass tube transmitting the unaltered ammonia, 

 but in that receiving it after its exposure to heat, moisture 

 was very distinct, and the gas appeared in the airholder 

 densely clouded. 



This circumstance seems distinctly to prove the forma-, 

 tion of water in this operation for the decomposition of am- 

 monia ; unless indeed it be asserted that the hydrogen and 

 nitrogen gases evolved, hold less water in solution or sus- 

 pension than the ammonia decomposed 5 an idea strongly 



* The apparatus in which this experiment was made is described in page 

 214, Journal of the Royal Institution. The gas was confined by mercury 

 which had been previously boiled to expel any moisture that might adhere to 

 it. The ammonia had been exposed to the action of dry pure potash, and a 

 portion of it equal in voiume to 10930 grains of mercury, when acted on by 

 distilled water, left a residuum equal to nine grains of mercury only. So 

 that the gas, there is every reason to believe, contained no foreign aeriform 

 matter; for even the minute residuum may be accounted for by supposing it 

 derived from air dissolved in the water. 



f Phil. Mag. vol. xxix. 



K 2 opposed 



