420 



SGIENGE. 



[N. S. Vol. II. No. 39. 



an instrument can only be obtained by a richly 

 endowed laboratory." His object is, therefore, 

 to simplify the method so as to bring the appa- 

 ratus within the reach of laboratories of only 

 moderate equipment. The method proposed 

 can scarcely be described here. Tests made 

 with it in recording the infra-red spectra of vari- 

 ous flames, appear, however, to be satisfactory. 

 The author's aim can perhaps best be stated in 

 his own words : "To construct an apparatus 

 which shall bear the same relation to that of 

 Langley as does the direct vision spectroscope 

 to the larger instruments of its class. ' ' 



On the Electrolytic Conductivity of Concentrated' 

 Sulphuric Acid: By K. E. Guthe and L. J. 

 Beiggs. The authors have determined the 

 conductivity of strong sulphuric acid at different 

 temperatures and concentrations, wifh especial 

 reference to the concentration corresponding to 

 the hydrate H2SO4+H2O. Measurements were 

 made by the bridge method with an alternating 

 current, a sensitive dynamometer being used 

 instead of a telephone. The results are given 

 in tables, and also in the form of four curves, 

 which show the relation between molecular 

 volume and molecular conductivity at tempera- 

 tures of 0°, 10°, 18° and 25°. Each of the four 

 curves has a well-marked minimum at the mole- 

 cular volume 32.1. If curves are drawn with 

 concentrations instead of molecular volumes 

 the minima do not occur at the same points. 

 From this the authors draw the important con- 

 clusion that ' it is not the concentration but the 

 molecular volume which determines the con- 

 ductivity of the acid.' Interesting results are. 

 obtained for the conductivity of the crystalline 

 hydrate £[2804 -fHoO. The values obtained are 

 perfectly definite, and appear to be free from 

 errors due to the presence of unsolidified acid. 

 The conductivity is found to be much smaller 

 than that of the liquid, even when the latter 

 is undercooled. A rapid diminution in resis- 

 tance is, however, noticeable as the temperature 

 approaches the melting point (7°. 5). 



Book Notices. Helm : Grundziige der Mathe- 

 matischen Chemie. Ostwald's Klassiker der 

 Exacten Wissenschaften. Mach : Popular Sci- 

 ence Lectures. Proceedings of the Electrical 

 Society of Cornell University. Naber : Stand- 

 ard Methods in Physics and Electricity criticised. 



NEW BOOKS. 



A Text-book of the Principles of Physics. Alfred 

 Daniell. 3d Edition. Kew York and Lon- 

 don. 1895. Pp. xv-f-782. $4.00. 



The Great Frozen Land. Frederick George 

 Jackson. London and New York, Macmil- 

 lan & Co. 1805. Pp. xviii+297- $4.50. 



Climate and Baths of Great Britain. (Vol. I.) 

 Being the report of a committee of the Royal 

 Medical and Chirurgical Society of London. 

 London and New York, Maemillan & Co. 

 1895. Pp. xvi + 640. $6.50. 



The Practice of Massage. A. Symons Eccles. 

 New York and London, Maemillan & Co. 

 1895. Pp. xii + 377. $2.50. 



The Theory and Practice of Counter Irritation. 

 H. Cameron Gillies. London and New 

 York, Maemillan &' Co. 1895. Pp. xii + 

 236. $2.50. 



The Production of Tin in Various Parts of the 

 W^orld. Charles M. Rolker. Washington. 

 Government Printing Office. 1895. Pp. 88. 



Handbuch der Physiol ogischen Optik. H. vON 

 Helmholtz. 2d Edition, Nos. 1-10. Ham- 

 burg und Leipzig, Leopold Voss. 1886- 

 1895. Pp. 800. 



CPraduate Courses. Compiled by an editorial 

 board of graduate students. New York, 

 Maemillan & Co. 1895. Pp. vi + 135. 25 cts. 



Proceedings of the Royal Society of Victoria. 

 Vol. VII., New Series. London, Williams 

 and Norgate. 1895. Pp. vi+339. 



The Psychology of Number. By James A. Mc- 

 Lellan and John Dewey. New York, D. 

 Appleton&Co. 1895. Pp. xiv+309. $1.50. 



The Beginnings of Writing. Walter James 

 Hoffman. New York, D. Appleton & Co. 

 1895. Pp. xiv-f209. $1.75. 



Frail Children of the Air. Samuel Hubbard 

 ScuDDER. Boston and New York, Houghton, 

 Mifflin & Co. 1895. Pp. viii + 279. $1.50. 



Alternating Electric Currents. Edwin J. Hot 

 TON and A. E. Kennelly. New York, Thy 

 W. J. Johnston Co. 1895. Pp. 225. $1.00. 



The Stone Industry in 1S94. Willian C. Day. 

 Washington, Government Printing Office. 

 1895. Pp. 83. 



