il SCIENCE.—ADVERTISEMENTS. 
NEW SCIENTIFIC BOOKS—Just Ready or in Press 
The Liquefaction of Gases 
Just Ready. Its RIis—E AND DEVELOPMENT. Cloth, 12mo, $1.50. 
By Wituerr LepLeyY HARDIN, Harrison Senior Fellow in Chemistry in the University of Penn- 
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A complete history of the development of the methods employed in the liquefac- 
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Popular “¢ Recent developments in the liquefaction of air and the recent liquefaction of hydro- 
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Industrial The various forms of apparatus are shown in illustrations. In addition to the history 
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BURBURY—A Treatise on the Kinetic 
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8vo, Cloth. Price, $2.00 net. 
Cambridge University Press. 
AREY —Elementary Chemistry. For HicH 
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Teacher of Chemistry and Physics in the High 
School, Rochester, N. Y. 
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woop SuTER, M.D., Professor of Ophthalmology, 
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LENGFELD—Inorganic Chemical Prepa= 
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This book gives directions for making about fifty 
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Blowpipe Analysis 
By FREDERICK Hutron German, Instructor in Chemistry in Stamford High School. Cloth, 
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This little book is designed for use in high schools, and also to serve as an aid to college students in 
the study of qualitative analysis. 
THE MACMILLAN COMPANY, Publishers, New York. 
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