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SPECIALTIES 



Standard Apparatus of New and ImproTed Deaiffiu 

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Astronomical Telescopes Dividing Engines 



Spectroscopes Comparators 



Micheleon Interferometers General Laboratory Apparatus 



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can be obtained from all dealers In chemical apparatus 



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THIRD EDITION, REWRITTEN AND ENLARGED 

 WITH COLORED PLATES 

 WHIPPLE— The flicroscopy of Drinking Water. 



By George Chandler Whipple, Gordon MoKay Professor of Sanitary Engineering, Harvard 

 University and tiie Massachusetts Institute of Technology. With a chapter on The Use of the 

 Microscope. By John W. M. Bunker, Ph.D. xxi+409 pages, 6x9, 74 figures, 6 full-page 

 plates in the text, and 19 plates of organisms in colors. Cloth, |4,00 net. 



SECOND EDITION, REVISED AND ENLARGED 

 HAZEN—C\ean Water and How to Get It. | 



By Allen Hazen, Member of the American Society of Civil Engineers, etc. xii+196 pages, 

 5}x8, containing 18 full-page half-tone illustrations. Cloth, $1.50. 



CARMICHAEL—The Theory of Numbers. 



Being No. 13 of the Mathematical Monograph Series. By Robert D. Caemichael, Asso- 

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X)JCB:S0JV— Elementary Theory of Equations. 



By Leonard Eugene Dickson, Ph.D., Professor of Mathematics in the University of 

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