Preparaikti of the refplrahle Niifous Oxide, J 1 5 



IX. 



Leiier from Mr. Davy, Superinlendant of the Pneumatic Injliiution, to Mr. Nicholson, 

 on the Nitrous Oxide, or Gafeous Oxide of Azote, on certain Fa8s relating to Heat and 

 Light, and on the Difcovery oj the Decompofition of the Carbonate and Sulphate of 

 Ammoniac. 



SIR, 



OINCE my difcovery of the refpirabllity, and extraordinary effefts of the gafeous oxide of 

 •azote in April, 1799, a great portion of my time has been devoted to experiments on it» 

 properties, conipofition, and mode of a£lion on living beings. Thcfe experiments are 

 nearly compJeated ; but as at leaft two months will elapfe before they can be publifhed, 

 and as fome of the izQ.% to which they relate have been made known to the world in 

 Dr. Beddoes's Notice, to prevent dangerous and inconclufive experiments, I beg leave to 

 communicate to the public, by means of your Journal, a fliort account of the mode in 

 which, it has ufualiy been prepared for experiments on refpiration. Nitrate of ammoniac 

 perfeftly neutralifed, and rendered as dry as poffible, mufl; be expofed to a heat not below 

 310, or above 400° of Fahrenheit*. At this temperature it is decompounded into water 

 and gafeous oxide of azote, or as I would rather call it, nitrous oxide. 



The gas mufl: be pafled through water, and fufFered to remain in contafl with it at leafl: 

 an hour and an half before it is refpired. A fufficient teft of its purity is the combuflion 

 of fulphur in it, with a vivid rofc coloured flame. The fame water (hould be ufed for 

 receiving it through, and retaining it in different experiments. A pound of dry nitrate of 

 ammoniac properly decompofed, produces rather more than four cubic feet of air. I have 

 found that the nitrous oxide may be likewife procured in a ftate of great purity, by expofing 

 nitrous gas to dry fulphite of pot-afli. i of nitrous gas decompofed in this manner, 

 produces nearly 0,5 of nitrous oxide. 



The folution of metals in dilute nitrous acid never produces air fufficiently pure for 

 refpiration, and the decompofition of nitrous gas by the fulphures, wetted iron, &c. is a 

 procefs too flow ever to be employed with advantage. 



My invefl,igation of the nature, properties, &c. of the nitrous oxide, and the aeriform 

 'fluids relating to it, will confifl:, 



J. Of experiments on its produ£lion, from the decompofition of nitrous acid and 

 nitrous gas in different modes, its analyfis, and the analyfis of the fubfl:ances conneded - 

 with it. 



2. On its adion on different incombufliible fubftances, on the combufl;ion of charcoal, 



* This decompofition was difcovered by the illuftiious Bertholkt. I have 'found that at a temperature 

 above joo", nitrous gas and nitrogene are evolved as well as nitrous oxide. Whenever there is a luminous 

 appearance in the retort, more or lefs of thefe two fubftances will be produced, 



3 fulphur 



