325 NATURE AND DECOMPOSITION OF THE FIXED ALKALIS. 



A more deci- employed by Mrs. Allen and Pepys for the combustion of 

 sive proo . ^^^ diamond, and these gentlemen kindly assisted in the ex- 

 periment. 



Very pure ammoniacal gas was passed over iron wire 

 ignited 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° ; and it v.'as 

 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 formation 

 of water in this operation for the decomposition of ammo- 

 nia ; unless indeed it be asserted, that the hidrogen and ni- 

 trogen gasses evolved hold less water in solution or suspen- 

 sion than the ammonia decomposed, an idea strongly op- 

 posed by the conclusions of Mr. Dalton* and the experi- 

 ments of Messrs. Dcsormes and Clement +. 



After the gas had been passed several times through the 

 ignited tube from onegazometer to the other, the results were 

 examined. The iron wire became converted superficially 

 into oxide, and had gained in weight ^Vo parts of a grain, 

 about -i^ of a grain of water were collected from the cooled 

 glass tubes by means of filtrating paper, and 33-8 cubic 

 inches of gas were expanded into 55-3 cubic inches, and by 

 detonation With oxigen it was found, that the hidrogen gas 

 in these was to the nitrogen as 3-2 to 1 in volume. 



It will be useless to enter into the more minute details of 

 this experiment, as no perfectly accurate data for proportions 

 can be gained from them ; for the whole of the ammonia was 

 not decomposed, and as the gas had been prepared by being 

 sent from a heated mixture of sal ammoniac and quicklime 

 into the airholder, it was possible, that some solution of 



* Manchester Memoirs, Vol. V, Part II, page 535, 1785. 

 i Aunales de Chemie, Vol. XLII, p. 125. 



ammonia 



