Geology and Mineralogy. 69 



iiomogenes; les dissolutions, pp. 1-380. Paris, 1898 (Librairie 

 Scientifique A. Hermann). — The third volume of the extensive 

 work by M. Duhem, which was announced in volume iii, p. 419, 

 of this Journal, has now been issued. It shows that the promises 

 made at the outset are being thoroughly fulfilled, and that the 

 work when completed will occupy a unique place in scientific 

 literature. 



The volume is divided into two parts; the first of these dis- 

 cusses homogeneous mixtures with respect to thermodynamic 

 potential, osmotic pressure and the hypotheses of Van t'Hofi and 

 d'Arrhenius ; also chemical reactions in homogeneous systems. 

 The second is devoted to solutions, discussing the solution of salts 

 in general, the effect of vaporization of the solvent, with the 

 formulas of Kirchhoff, the effect of freezing of the solvent, saline 

 and gaseous hydrates, and double salts. This enumeration of the 

 subjects of leading chapters will serve to show the scope of this 

 part of M. Duhem's work, but only close study will make the 

 reader familiar with the thoroughness of the discussion as a whole. 



11. Prismatic and Diffraction Spectra. Memoirs of Joseph 

 von Fraunhofer. Translated and edited by J. S. Ames. — The 

 inauguration of the series of Harper's Scientific Memoirs was 

 announced in the last number of this Journal (p. 504, Dec, 1898). 

 The second volume has now been issued ; it contains translations 

 of Fraunhofer's classical papers (181Y-1828). To these are added 

 the note by Wollaston (1802) describing the method by which he 

 obtained a pure solar spectrum and discovered the presence of 

 fixed lines in it. This volume, like its predecessor, is edited by 

 Prof. Ames. 



II. Geology and Mineralogy. 



1. Maryland Geological Survey; William B. Clark, State 

 Geologist. Vol. i, pp. 1-539, plates i-xvii, 189'7; Vol. ii, pp. 

 1-509, plates i-xlviii, figures 1-34, 1898. — Maryland was one 

 of the first four states in the Union to institute an official 

 geological survey, and, in the present series, is preparing the 

 most elaborate and elegant geological reports that any state has 

 «o far produced. This second official survey of the state was 

 organized by act of the General Assembly in March, 1896. The 

 commission appointed Prof. Wm. B. Clark state geologist, and 

 the two volumes are the work of the first and second years of the 

 survey. The first volume, as the geologist says in the preface, 

 "consists primarily of a summary of past and present knowledge 

 concerning the physical features of Maryland, and embraces an 

 account of the geology, physiography and natural resources of 

 the state. The " Historical sketch," comprising Part ii, begins 

 with the landing of Captain John Smith, in 1608, and narrates 

 the work of the successive explorers and investigators who have 

 developed the knowledge of the resources of the state. Part iv, 

 on the Bibliography and Cartography, is compiled by Mr. E. B. 



