il SCIENCE.—ADVERTISEMENTS. 
NEW SCIENTIFIC BOOKS—Just Ready or in Press 
The Liquefaction of Gases 
Just Ready. Its RISE AND DEVELOPMENT. Cloth, 12mo, $1.50. 
By Wittetr LEPLEY HARDIN, Harrison Senior Fellow in Chemistry in the University of Penn- 
sylvania. 
A complete history of the development of the methods employed in the liquefac- 
tion of gases, as the following clipping from the preface will show : 
Popular “Recent developments in the liquefaction of air and the recept liquefaction of hydro- 
Up-to-date gen have added considerable interest to the whole subject of the liquefaction of gases. 
The literature on this subject is scattered, for the most part, in foreign journals, and is 
inaccessible to a majority of those who are interested in scientific work. 
Scope of ‘‘The object of this little volume is to present a complete history of the development 
the Book of the methods employed in the liquefaction of gases. Sufficient theory has been given to 
enable the popular reader to understand the principles involved. While the book has been 
written in a popular-science style, an effort has been made to make it of value to those who 
are especially interested in the subject by giving the references to the original literature.’” 
Industrial The various forms of apparatus are shown in illustrations. In addition to the history 
Application of the development of the methods, the condition of matter at the critical point, the theory 
of the gaseous and liquid states of matter, and the theory of the regenerative method of 
refrigeration are also considered. In the conclusion, a brief outline is given of researches 
at low temperatures and of the industrial application of liquefied gases. 
THOMPSON—Light Visible and Invisible. 
A Series of Popular Lectures delivered by SYLVA- 
SUTER—Handbook of Optics. For Srv- 
DENTS OF OPHTHALMOLOGY. By WILLIAM NOR- 
wus P. THompPson, D.Sc., M.R.I., F.R.S., author 
of ‘‘Elementary Lessons in Electricity and Mag- 
netism,’’ etc. Cloth, 12mo, $1.50. 
“Popular and extremely interesting from begin- 
ning to end.’’—The Independent. 
“Reliable and up-to-date . . . of great value to 
the student.’’—Journal of Education. 
BURBURY—A Treatise on the Kinetic 
Theory of Gases. By S. H. Burpury, M.A., 
F.R.S., late Fellow of St. Johns, Cambridge. 
8vo, Cloth. Price, $2.00 net. 
Cambridge University Press. 
MACBRIDE—The Slime Moulds. A Hanp- 
BOOK OF NORTH AMERICAN MyXoOMYCETES. By 
THOMAS H. MAcBRIDE&, Professor of Botany, Uni- 
versity of Iowa. 
A list of all species described in North America 
including Central America. Each description is ac- 
companied by annotations. 
12mo, Cloth, $2.25 net. © 
Woop SuTER, M.D., Professor of Ophthalmology, 
National University, and Assistant Surgeon, Epis- 
copal Eye, Ear and Throat Hospital, Washington, 
D. C. i Cloth, 16mo, $1.00 net. 
The object of this book is to give the student a 
clearer insight into the phenomena of refraction as 
applied to ophthalmology than can be obtained from 
the usual text-books on Refraction of the Eye. 
LANGE—Our Native Birds. How To Pro- 
TECT HEM AND ATTRACT THEM TO OUR HOMES. 
By D. LANGE, Instructor in Nature Study in the 
Schools of St. Paul, Minn., author of a ‘‘ Manual 
of Nature Study.” Cloth, 12mo. Nearly Ready. 
LENGFELD—Inorganic Chemical Prepa= 
rations. By FrLt1x LENGFELD, Assistant Pro- 
fessor of Inorganic Chemistry in the University of 
Chicago. Cloth, 16mo, 60 cents nef. 
This book gives directions for making about fifty 
substances, and is intended for college students with 
some knowledge of analytical chemistry. 
Blowpipe Analysis 
By FREDERICK HuTTon GETMAN, Instructor in Chemistry in Stamford High School. 
1émo. Just Ready. 60 cents net. 
Cloth, 
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. 
