ISO On the Decomposition and Composition 



The results of an experiment that I made in 1799* give 

 the weight of 100 cubic inches of ammonia, as 18*18 grains 

 at the mean temperature and pressure. I had reasons how- 

 ever for suspecting that this estimation might be somewhat 

 too low, and on mentioning the circumstance to Messrs. 

 Allen and Pepys, they kindly undertook the examination of 

 the subject, and Mr. Ailen soon furnished me with the fol- 

 lowing data. " In the first experiment 21 cubic inches of 

 ammonia weighed 4*05 grains; in a second experiment the 

 same quantity weighed 4*06 grains, barometer 30*65, ther- 

 mometer 54° Fahrenheit." 



Now if the corrections for temperature and pressure be 

 made for these estimations, and a mean taken, 100 cubic 

 inches of ammonia will weigh 18*67 grains, barometer 

 being at 30, and thermometer at 6";/ Fahrenheit; and if the 

 quantity used in the experiment of decomposition be calcu- 

 lated upon as cubic inches, 60 will weigh 11*2 grains. But 

 the hydrogen gas evolved equal to 80 will weigh 1*93 + 

 grains, and the nitrogen equal to 2.SJ, 8*3. And 11*2 

 grains — 1*9 4- 8*3 = 10*2. and 11*2 — 10*2. = 1, all the 

 estimations being made according to the standard tempera- 

 lure and pressure. 



So that, in this experiment on the decomposition of am- 

 monia, the weight of the gases evolved is less by nearly 

 T ' T than that of the ammonia employed ; and this loss can 

 only be ascribed to the existence of oxygen in the alkali; 

 part of which probably combined with the platina wires em- 

 ployed for electrization, and part with hydrogen. 



After these ideas the oxygen in ammonia cannot well be 

 estimated at less than seven or eight parts in the hundred ; 

 and it possibly exists in a larger proportion as the gases 

 evolved may contain more water than the gas decomposed/ 



* Researches Chem. and Phil, page 62. 



j- Lavoisier's Elements, p. 569. A cubical inch of hydrogen is considered 

 as weighing 0239. 



$ Researches Chem. and Phil, page 9. From my experiments 100 cubical 

 inches of nitrogen weigh at the standard temperature and pressure, 2CS 

 grains. 



which 



