314 Mr. J. Stevenson on the Chemical and 



sulphides, and even in very primitive rocks the presence of 

 oxidizable matter has been observed. 



Probably the first chemist who pointed out this circum- 

 stance clearly, and based a theory of the history of the 

 atmosphere upon it, was Prof. C. J. Koene, of Brussels, the 

 contemporary and rival of Stas. In 1856, or thereabouts, 

 he published a short series of popular lectures in which he 

 enunciated the theory that there was no oxygen in the earth's 

 primeval atmosphere, his reason for adopting this view being 

 that oxidizable matter is found in the earth's primitive rocks. 

 He held that the earth's primitive atmosphere consisted of 

 nitrogen, carbonic acid, and aqueous vapour; and he also 

 considered that the proportion of oxygen in the atmosphere 

 had gone on increasing during geological history, while the 

 proportion of carbonic acid and of nitrogen had gone on 

 decreasing. In holding such views he differed very notably 

 from previous and contemporary chemists, for example, 

 Dumas and Liebig, who considered that the proportions of 

 carbonic acid and of oxygen in the atmosphere were fixed and 

 constant ; and still more from Berzelius and Mulder, who 

 were of opinion that the proportion of carbonic acid was 

 increasing and the proportion of oxygen decreasing in the 

 atmosphere, owing to respiration, fermentation, volcanic action, 

 and human industry. 



These statements about Prof. Koene are derived from an 

 interesting series of articles which appeared in the ' Chemical 

 News' at intervals during 1893 and 1894 (vols. 67, Q8, 

 69, 70), and were written by Dr. T. L. Phipson, F.C.S., 

 who had himself studied chemistry under Koene at Brussels. 

 In these articles he describes Koene's views on the history of 

 the atmosphere, and then proceeds to give certain modifi- 

 cations and additions of his own. In particular, he thinks 

 that the constituents of the primitive atmosphere may quite 

 well be reduced to the element of nitrogen alone, as he 

 considers that the carbonic acid present at any time on the 

 surface of the earth would be practically all dissolved in 

 water. He thinks that carbonic acid was produced regularly 

 and steadily throughout geological history by volcanic action, 

 but also (apparently) that there was never a very large 

 quantity of it existing on the earth in the free state at any 

 one time, as it was constantly being decomposed by vegetation 

 into free oxygen and the carbon of vegetable matters and of 

 (ultimately) coal. 



Dr. Phipson confirmed and amplified his views by a 

 number of beautiful and interesting experiments on the 

 growth of vegetation in various gases instead of ordinary air. 



