Reviews 



An Introduction to Chemical Crystallography. By P. Groth. 

 Translated by Hugh Marshall. New York : John Wiley & 

 Sons, 1906. 



A short treatise on the relations between the properties of crystals 

 and their chemical constitution, with special reference to the structure 

 of crystals. The treatment assumes a knowledge of the laws of crystal- 

 lography as set forth in such works as Groth 's Physikalische Krystal- 

 lographie. No attempt is made to review the history of the develop- 

 ment of chemical crystallography; the subject is taken up in its present 

 stage of advancement and the relations so far established are stated in 

 principle and illustrated by specific examples. 



The chief phases of the subject which are discussed may be briefly 

 mentioned: crystal structure and its possible varieties, involving ideas 

 of polymorphism or physical isomerism, pseudosymmetry and polysym- 

 metry, as well as those of the crystal molecule; special consideration of 

 polymorphism; a comparison of the crystal structures of chemically 

 allied substances — morphotrophy ; isomorphism, including a discussion 

 of the similarity of crystal structure in substances possessing analogous 

 chemical constitution; the relations between crystals and solutions of 

 isoinorphous substances, and isomorphous mixtures; and so-called molecu- 

 lar compounds. 



Chemical crystallography, while essentially a part of physical chem- 

 istry and of special interest to the chemist, is of such fundamental impor- 

 tance in the study of minerals and rocks that this translation of the treatise 

 by Professor Groth will be particularly acceptable to the mineralogist 

 and petrologist.. • J. P. I. 



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