176 PROCEEDINGS OP THE AMERICAN ACADEMY 



experimenting, for no more certain confirmation could have been 

 reached than that furnished by a comparison of Dumas's results with 

 those of this paper. 



Since this investigation was essentially finished, and the results com- 

 municated to the American Academy at their meeting of June 15, 

 1887, we have received from the author a " Sonderabdruck " from the 

 " Berichte der Deutschen Chemischen Gesellschaft," dated the 26th of 

 July following, and entitled : " E. H. Keiser : Ueber die Verbrennung 

 abgewogener Mengen von Wasserstoff und iiber das Atomgewicht des 

 Sauerstoffs." In this paper Mr. Keiser distinctly recognizes the im- 

 portance of directly weighing the hydrogen in the determination of 

 the atomic weight of oxygen, and quotes the remarks of Dumas given 

 above. He has also devised a very ingenious method of weighing 

 hydrogen when occluded by palladium ; but the preliminary results 

 he publishes are far from haviug the degree of accuracy required, and 

 lead us to infer that, like our own preliminary results, they must be 

 vitiated by varying impurities in the hydrogen ga3 used. The three 

 determinations whose results he publishes gave for the atomic weight 

 of oxygen respectively 15.873, 15.897, and 15.826. 



We are sorry if Mr. Keiser has entered- on somewhat the same field 

 which we have so long occupied without knowledge of our work. 

 But, as above stated, our investigation was begun more than five 

 years ago ; and the methods employed have been freely explained to 

 the many chemists, both American and European, who have visited 

 Cambridge during the interval. We earnestly hope that Mr. Keiser 

 will carry out his investigation ; for so important a constant as the 

 atomic weight of oxygen cannot be too often verified. 



J. P. C. Cambridge, December 15, 1887. 



