PREFACE. 



The apparatus to be described in this report has been in process of 

 development for twelve years. During this time the resources of Wes- 

 leyan University have been supplemented by appropriations from the 

 United States Department of Agriculture and the Connecticut (Storrs) 

 Agricultural Experiment Station, and by contributions from private 

 individuals. In aid of a series of experiments with the apparatus in its 

 earlier stages, grants from the Elizabeth Thompson Science Fund and 

 the Bache Fund were obtained. The addition of the apparatus for the 

 determination of oxygen was made possible by liberal grants from the 

 Carnegie Institution of Washington. 



In the development of apparatus necessarily so elaborate as this the 

 active cooperation of a skillful instrument builder is absolutely essential. 

 It has been our good fortune to have the service of Mr. S. C. Dinsmore, 

 whose mechanical skill has insured the successful operation of many 

 parts of the apparatus. Dr. Paul Murrill, formerly associated with 

 this research, rendered invaluable assistance in devising the methods 

 of computation. Mr. R. D. Milnerand Mr. H. L,. Knight have assisted 

 materially in the preparation of this report. 



Dr. E. B. Rosa, physicist of the National Bureau of Standards, but 

 previously professor of physics at Wesleyan University, was actively 

 engaged in this investigation in its earlier stages and has subsequently 

 from time to time given advice which has assisted greatly in the 

 furtherance of the work. 



The first grant of the Carnegie Institution for the development of 

 the apparatus for the direct determination of oxygen was made to my 

 colleague, Prof. W. O. Atwater. It was then expected that the report 

 containing the description of the apparatus would be issued under the 

 joint authorship of Professor Atwater and the writer. It has been 

 deemed fitting, therefore, to retain his name on the title page of this 

 report. A serious illness has compelled his untimely retirement from 

 the work, and the writer, who has had the personal supervision of the 

 development of the apparatus since 1895, has continued the research. 



Inasmuch as this report has been written, some of the apparatus 

 herein described has been developed, and the experiment with man has 

 been carried out subsequent to Professor Atwater's retirement, the writer 

 assumes full responsibility for this report as it stands, and against him 

 alone should adverse criticism be directed. 



FRANCIS GANG BENEDICT. 

 August, 1905. 



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