Page:Proceedings of the Royal Society of London Vol 1.djvu/365

On Respiration. By William Allen, Esq. F.R.S. and William Hasledine Pepys, Esq. F.R.S. Read June 22. 1809. [Phil. Trams. 1809, p. 404.]

Experiments on Ammonia, and an Account of a new Method of armlysing it, by Combustion with Oxygen and other Gases; in a Letter to Humphry Davy, Esq. Sec. RS. &c. from William Henry, M.D. F.R.S. V.P. of the Lit. and Phil. Society, and Physician to the Infirmary, at Manchester^[1]. [Phil. Trans. 1809, p. 430.]

Dr. Henry having detected a fallacyin 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 smallest 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 degree of moisture was perceptible, even this appearance varied in degree; 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 714 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 ammonia, the mixtures are not combustible ; but when any intermediate quantity of oxygen is employed, the ammonia is consumed in proportion, 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

1. This letter, in its original form, was read to the Society, May 1831,1809; 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.