May 11, 1900.] 



SCmNGE. 



14.1 



and is abundant in embryonic tissues ; its exact 

 r6Ie cannot be defined. Tlie relation of the 

 element sodium to the organism is most proble- 

 matical ; it may exert a stimulating effect upon 

 protoplasm, or its presence in the substratum 

 may facilitate beneficial chemical changes. It 

 does not enter into the composition of the plant 

 in appreciable quantity however. The bulletin 

 does not give adequate treatment to the pure 

 mechanical functions of salts in the maintenance 

 of turgidity, and it might have gained in value 

 to the agricultural experimenter by the deline- 

 ation of lines of practical investigation to be 

 followed. It is highly controversial in parts 

 and one is impressed with the very great differ- 

 ences of conclusions which may be reached from 

 a consideration of the same facts by a compari- 

 son with the sections of Pfeffer's Plant Physi- 

 ology or any other publication treating the 

 same subject. D. T. MacDougal. 



Science Sketches: Chemistry its Evolution and 

 Achievements. By Ferdinand G. Wiech- 

 MANN, PhD. New York, William E. Jenkins. 

 1899. Pp. vii + 176. 



The study of the evolution of chemical science 

 from its earliest beginnings possesses a fasci- 

 nating interest. The author of this little book 

 has endeavored so to present the subject as to 

 make it useful to all who take a general inter- 

 est in science. In matters which pertain to the 

 development of chemistry before the nineteenth 

 century the treatment is satisfactory. For the 

 present century the book does not altogether 

 succeed in tracing the evolution of the science. 

 It seems rather to give a series of more or less 

 isolated facts about the growth of chemical 

 knowledge than to give a clear picture of the de- 

 velopment of the science. Perhaps this should 

 not be too severely criticised, for it is immensely 

 difficult to give such a picture for the period in 

 question. 



If the theory that diamonds are extra-terres- 

 trial in origin has actually been proposed by any 

 one as suggested on p. 117, it must have arisen 

 from a curious confusion as to Moissan's thought 

 in the matter. Moissan says that in discover- 

 ing the diamonds in the meteorites he has 

 'caught nature in the act,' meaning, not that 

 the diamonds were in the meteorites as they 



flew through space, but that they were formed 

 during the passage of the meteorite through the 

 air and its subsequent cooling. This thought 

 seems to have guided Moissan in his successful 

 production of diamonds. 



In the discussion of liquid air the failure to 

 mention the pioneers Cailletet and Pictet is re- 

 markable. Some reference should also have 

 been made to the Linde machines by which 

 liquid air is now produced in quantity on es- 

 sentially the same principle as that used by 



Tripler. „, , ,-, 



^ W. A. NOYES. 



BOOKS EKCEIVED. 



Scientific Papers. Peter Guthrie Tait. Cam- 

 bridge, The University Press. 1900. Vol. II. 

 Pp. 500. 



Railroad Construction, Theory and Practice. Walter 

 LoRiNG Webb. New York, John Wiley & Sons; 

 London, Chapman & Hull, Ltd. 1900. Pp. x 

 -+-456. 



Introduction to Science. Alexander Hill. Lon- 

 don, J. M. Dent & Co. Pp. 140. 



SCIENTIFIC JOTJBNALS AND ARTICLES. 



The April number (Vol. I., No. 2) of the 

 Transactions of the American Mathematical So- 

 ciety contains the following articles : ' On the 

 metric geometry of the plane n-line,' by F. 

 Morley ; 'On relative motion,' by Alexander 

 S. Chessin ; ' Plane cubics and irrational cova- 

 riant cubics,' by Henry S. White; 'A purely 

 geometric representation of all points in the 

 projective plane,' by Julian Lowell Coolidge ; 

 ' The decomposition of the general collineation 

 of space into three skew reflections,' by Edwin 

 B. Wilson ; ' A new method of determining the 

 differential parameters and invariants of quad- 

 ratic differential quantics,' by HeinrichMaschke; 

 ' On the extension of Delaunay's method in the 

 lunar theory to the general problem of plane- 

 tary motion,' by G. W. Hill ; ' On the types of 

 linear partial differential equations of the second 

 order in three independent variables which are 

 unaltered by the transformations of a continuous 

 group,' by J. E. Campbell. 



The May number of the Bulletin of the Amer- 

 ican Mathematical Society contains the follow- 

 ing articles : ' On the geometry of the circle,' 

 by Dr. Virgil Snyder ; ' Isomorphism between 



