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172 E. W. Morley— Oxygen in the Arr. 
therefore constant. 
When the writer planned to make analyses of air in order to 
detect if possible some law in its variations of composition, he 
expected to have to do with quantities but little larger than 
the errors of observations. Some thought was therefore given 
to the methods of keeping such errors as small as possible. 
puted the comparative accuracy of ana of air made with 
the long eudiometer of Bunsen’s experiments, and with the 
apparatus used in the present work. e first analysis by 
analysis quoted from Bunsen. 
