Philosophical Society of London. 377 



drogen and oxygen, or water deprived of part of its oxygen. 

 He found nitrogt^n to be produced in ail cases where water 

 in a state of vapour was passed over any matter at a iiigh 

 degree of iieat, tiiat would abstract part of its oxygen. He 

 denied that this change was ownig to the introduction of 

 atmospheric air through the pores of the tubes, for he found 

 the same when they were covered externally with a glass, 

 or with a class tube placed in an earthen or metallic one, 

 provided anv metallic body were placed within. Berthollet 

 and La Grange, however, were induced from their im- 

 portance to repeat the experiments of Ginanner, but with all 

 their attention to accuracy could not detect the smallest por- 

 tion of mtrogen. This positive contradiction of two chemists 

 so justly famed for the accuracy of their experiments, 

 brcueht the assertions of Girtanner into disrepute, who, 

 from the looseness of his style, was perhaps justly considered 

 as an inaccurate chemist and an enthusiastic theorist. This 

 opinion of chemists concernmg the nature of nitrogen was 

 Ujost perfectly seitled : since this tin)c it continued to be 

 considered as a simple body, till the brilliant discoveries of 

 Sir Humphry Davy burst forth on the science of chemistry 

 with a most dazzluig splendour, and diffused a new light 

 on the nature of the material world. Sir Humphry Davy, 

 induced by his discoveries of the nature uf the fixed alkalies 

 and earths, was led to examine the volatile alkali .ammonia, 

 and, from some experiine.'^ts detailed in his second Bakeriaa 

 lecture, concluded that ox\ gen entered into its composition. 

 This he could only account for by supposing either hydrogen 

 to be an oxide of nitrogen, or nitrogen to be an oxide of 

 hydrogen. About the same time Messrs. Allen and Pepys 

 were engaged in experiments on the products of respiration, 

 who found that under certain circumstances there was a 

 loss of oxygen and a considerable production of nitrogen. 

 Sir H. Davy, continuing his experiments, found a consider- 

 able loss of nitrogen during the action of the fusible com- 

 pound of potassium and nitrogen on matter containing 

 oxygen, its place being supplied by a corresponding pro- 

 duction of hydrogen and oxvgen ; he hence concluded that 

 '' the decomposition and composition of nitrogen seem 

 jiroved, allowing the correctness of the data, and one of its 

 elements appears to be oxygen." Sir H. Davy, however, 

 liom his more recent researches and more refined experi- 

 ments, began to doubt the accuracy of his previous con- 

 clusions ; he has now in a great measure renounced his 

 former views of the nature of nitrogen, and now again 

 glasses it among the simple substances. 



Towards 



