1824.] the Atriform Compounds of Nitrogen. 345 



lead and also of nitrate of baryta, each without addition, at 

 high temperatures. The results, however, for reasons which he 

 has stated (same work, p. 405) were not satisfactory. On again 

 reading his memoir, it occurred to me that a more complete 

 decomposition of nitrate of baryta would probably be obtained 

 by exposing it to a sufficient heat, in a state of intimate mixture 

 with charcoal ; and that the elements of the nitric acid would 

 be evolved in the state of carbonic acid and nitrogen gases, 

 products which admit of being easily and exactly separated from 

 each other. 



In my first trials of this process, I failed from the employment 

 of too little charcoal, in consequence of which much nitrous 

 acid vapour passed over, and acted upon the mercury over 

 which the gases were collected. After repeating the operation 

 several times, with various proportions of the materials, I found 

 that by using at least 1 part of charcoal to 2\ of the nitrate of 

 baryta, nitrous acid vapour was no longer evolved. In an expe- 

 riment made with great care, the barytic salt was finely pulve- 

 rised, and exposed for a whole day, with surfaces frequently 

 renewed, to a temperature of 212° Fahr. It was then mixed 

 with the powdered charcoal, which had been recently ignited in 

 a close vessel, to expel any moisture it might contain, and which 

 was still hot ; and a portion of quartz in very small grains, equal 

 in weight to the nitrate, was added to prevent the deflagration 

 from being too rapid. The mixture was put into a green glass 

 tube of the diameter of a common quill, into the upper part of 

 which, before bending it so that it might pass beneath the 

 mercury of the trough, a known weight of iron wire coiled into 

 a spiral form was introduced. Under this part of the tube a 

 double row of burning spirit lamps with flat wicks was placed ; 

 and when the iron wire appeared red hot, the mixture at the 

 bottom of the tube was heated by another lamp, at first mode- 

 rately to expel any moisture, that might have been absorbed 

 from the air while the tube was being filled, and then more 

 strongly so as to set the mixture on fire. By slowly moving the 

 flame of the lamp under that part of the tube which contained 

 the mixture, from above downwards, the combustion spread 

 gradually through the whole, and the gaseous products were not 

 more rapidly evolved than was consistent with their being 

 wholly collected. They proved to be more complicated than I 

 expected ; for not only carbonic acid and nitrogen were obtained, 

 but nitrous gas, carbonic oxide, and a very small quantity of 

 hydrogen, the last of which would indicate the presence of water 

 iu the proportion of about 0-7 of a grain to 100 of the nitrate and 

 the materials added to it. 



In the tube there remained, besides charcoal, carbonate of 

 baryta, with a very small quantity of that earth in its pure state, 

 but no undecornposed nitrate. After separating the pure baryta 



