526 



SCIENCE. 



[K. S. Vol. I. No. 19. 



any, of the characteristic plants found in the 

 lower strata of the Potomac of Virginia, 

 while angiosperms overwhelmingly predom- 

 inate in each. Until the Japanese beds 

 show angiosperms they cannot be consid- 

 ered as young as the uppermost portion of 

 the lower Potomac, which, in the Brooke 

 locality, Vu-ginia, and at Baltimore, Marj^- 

 land, show manj^ angiosperms. 



Prof. Yokoyoma has followed Prof. Natli- 

 orst in changing from Dioonites to Zamio- 

 phyllum, the name of a cycad that, so far, 

 is confined to the lower Cretaceous. This 

 is the species known as Dioonites Buchianus. 

 This change does not seem to be called for. 

 The reason assigned by Prof. Nathorst 

 does not seem weighty enough to remove a 

 name so well fixed as this, and, if a change 

 be made, the name Zamiophyllum seems 

 open to more objections than Dioonites. 

 The leaflets of Zamia are articulated at 

 their junction with the rachis and deciduous, 

 characters which are decidedly not found in 

 Dioonites Buchianus. These features seem 

 to be of more importance than the obliquity 

 of the leaflets and their narrowing towards 

 the base, which characters in Dioonites 

 Buchianus Professor N'athorst presents as 

 objections to regarding this plant as a 

 Dioonites. Wm. M. Fontaine. 



UNIVEESITY of ViEGIKIi:. 



Repetitorium der Chemie. By Dr. Gael Ar- 

 nold. Sixth Revised and Enlarged Edi- 

 tion. Hamburg and Leipzig, Leopold 

 Voss. 1894. 8°. Pp. x-t-613. Paper. 

 Price, 6 marks. 



This book has been written for medical 

 students and is intended to be used by them 

 as a convenient reference book in connec- 

 tion with lectures upon inorganic and or- 

 ganic chemistry and in preparing for ex- 

 aminations. That there is a demand for 

 such a book is shown by the fact that since 

 it first appeared, in 1884, six editions have 

 been called for. 



The work is divided into three sections. 

 In the first one of fifty pages the general 

 principles of the science are considered. 

 Such topics as the laws of stoichiometry," 

 the atomic and molecular theorj", the deter- 

 mination of molecular and atomic weights, 

 theorj' of valence, constitutional formulas 

 and the periodic classification of the ele- 

 ments are here discussed. The treatment 

 of these subjects is necessarily verj' brief and 

 is not intended to be exhaustive. As far 

 as it goes, however, it is clear and concise, 

 and, on the whole, the views of the author 

 represent fairly well the present position of 

 the science. To a few statements, such as 

 those on pages 6 and 31 that heat, light, 

 electricity and chemical aflinity are known 

 to be diifereut forms of motion (bekannfUch 

 nur verschiedene Beivegiingsformen darsteUen), 

 one is inclined to take exception. 



The second section of 216 pages deals with 

 descrij)tive inorganic chemistry. The ele- 

 ments are arranged under two heads, first 

 the non-metals, then the metals. The more 

 important facts as to the occurrence, prepa- 

 ration and properties of each element and 

 its chief compounds are here systematical! j' 

 and concisely presented. Newly discovered 

 facts in this field of chemistry have not been 

 overlooked. Thus, for example, we find 

 here described the preparation of azoimide, 

 H N" 3 , from inorganic substances ; the elec- 

 trolytic preparation of aluminium and mag- 

 nesium ; the statement that red phosphorus 

 is crystalline, etc. 



The last section of 295 pages gives a sum- 

 mary of the more important facts of organic 

 chemistrJ^ After some preliminarj' para- 

 graphs ui^on the analysis of cai-bon com- 

 pounds, molecular weight determination, 

 constitutional formulas and stereochemis- 

 try, the organic compounds are taken up in 

 the iisual way. In connection -with each 

 class of compounds the general behavior 

 and chemical characteristics of the class 

 are discussed. In this section of the book. 



