376 Philosophical Society of London. 



From its possessing no other properties than those of the 

 individual gases, and from artificial mixtures in various pro- 

 portions always comporting themselves in similar relations, 

 it has been universally agreed to be merely a mechanical 

 mixture uf the two gases. But, as the composition of the 

 atmosphere is uniformly the same in whatever situation it 

 is fouud, this opinion seemed to the lecturer somewhat pro- 

 blematical. As so vast a quantity of oxygen is constantly 

 consumed in respiration for the support of animated crea- 

 tion, and as the proportion of the oxygen to the nitrogen is 

 ever invariably the same, it has never been satisfactorily ex- 

 plained how the equihbrium is restdred. There most pro- 

 bably exist some unknown processes in nature, by which a 

 quantity of oxygen is generated corresponding to that con- 

 sumed by animals, by the combustion of inflammable bo- 

 dies, &c. To this it has been said, thai the vegetable 

 world is the organ by which this supply is effected ; that 

 the leaves of plants absorb the carbonic acid formed in 

 respiration, which retain the carbon and give out in return 

 the 'jxvgen. To this however the lecturer stated many ob- 

 jections. How is it that in the depth of winter, when a 

 complete check is given to vegetation, when plants possess 

 no leaves to effect a supply, when at the same time the 

 consumption of oxygen is so considerably increased by the 

 combustion of inflammables for the generation of warmth, 

 &c. how is the ox\gen in such times restored ? This ob- 

 iection it does not appear easy to obviate. There most 

 probably exist some provisions of nature of which we are 

 entirely ignorant, and these perhaps are only to be found in 

 the na'lure of nitrsigen. 



With respect to the nature of nitrogen he entered at 

 some considerable length, and gave a minute history of the 

 .earlitr cperiments of Priestley, of Gottling, Wiegleb, and 

 Crell ; of Dieman, Van Stroostwyck, ot Van Hausch Juch, 

 Van Mons, of Girtanner, and of Berthollet and Lagrange. 



The German chemists had found water converted into 

 nitrogen when passed in a state of vapour through ignited 

 earthen tubes, and hence concluded nitrogen to be a com- 

 pound of water and caloric. The Dutch chemists denied 

 this conversion of water into nitrogen, conceiving its pre- 

 sence to have been derived from the introduction of atmo- 

 spheric air through ihe interstices of the tube. Girtanner, 

 on the cunirarv, assi-rted the correctness of the German 

 chtiiu.<ts, nul co.ifirmed bv experiments of his own the 

 formation of iiitrogui, though he differed with them as to its 

 nature. He conceived nitrijgen to be a combination of hy- 

 drogen 



