345 



On Respiration. % William Allen, Esq. F.R.S. and William Hasle- 

 dine Pepys, Esq. F.R.S. Read June 22, 1809. [Phil. Trans. 

 1809,^.404.] 



Experiments on Ammonia, and an Account of a new Method of ana- 

 lysing it, by Combustion with Oxygen and other Gases ; in a Letter 

 to Humphry Davy, Esq. Sec. R.S. Ssc.from William Henry, M.D. 

 F.R.S. V.P. of the Lit. and Phil. Society, and Physician to the In- 

 firmary, at Manchester*. [Phil. Trans. 1809, p. 430.] 



Dr. Henry having detected a fallacy in the experiments lately com- 

 municated to the Society, in which oxygen gas appeared to be evolved 

 from ammonia by electric discharges, has repeated the experiments 

 with more care, and is now satisfied that no portion whatever of 

 oxygen gas can be separated. 



He next endeavoured to detect the production of water, which 

 would equally establish the existence of oxygen as a constituent ; 

 and though mere electrization did not enable him to discover the 

 smdlest quantity of moisture, he hoped, by exposure of the gas to a 

 freezing mixture, that it might be detected. 



But although, by a cold equal to zero of Fahrenheit, a slight de- 

 gree of moisture was perceptible, even this appearance varied in de- 

 gree ; and Dr. Henry was ultimately convinced, that even this arose 

 from the mercury, or from some extraneous source. 



With regard to the quantity of nitrogen and hydrogen gases evolved 

 from ammonia by electrization, Dr. Henry is of opinion that they 

 have been underrated by Mr. Davy, and that the proportion they 

 bear to each other is not exactly what it has been represented. Ac- 

 cording to Dr. Henry, 100 of ammonia give 198'78; and the pro- 

 portion of hydrogen to nitrogen is as 71 '4 to 28' 6 in the 100. 



On account of the tedious labour of decomposing any quantity of 

 ammonia by the mere repeated shocks of electricity, the author was 

 induced to seek some new method of operating, and after various 

 trials succeeded to his satisfaction, by detonation with oxygen. When 

 more than three parts of oxygen gas are mixed with one of ammonia, 

 or when so little as only half of oxygen is mixed with one of am- 

 monia, the mixtures are not combustible ; but when any intermediate 

 quantity of oxygen is employed, the ammonia is consumed in pro- 

 portion, and entirely disappears if the oxygen is more than double 

 its bulk. 



Dr. Henry, however, discovered an important advantage of using 

 an under proportion of oxygen ; for though the whole of the hydrogen 

 is not then consumed, yet the whole of the ammonia is decomposed; 

 for after detonation the remaining hydrogen, and the whole of the 



* This letter, in its original form, was read to the Society, May 18th, 1809; some 

 new observations were added, and some corrections furnished by the author, in 

 consequence of subsequent experiments made in June; it was transmitted to the 

 Secretary for publication July 10. 



