REVIEWS 483 



work includes an account of the chief theories of the present day, and a 

 summary and very general consideration of the more important functions. 



Close on one-third of the book is devoted to the Introduction and General 

 Theories. The author includes a brief sketch of Dalton's Atomic Theory, 

 and of Avogadro's law, which are not usually given in organic chemistry 

 books. Perhaps the best section of this chapter is that on Stereochemistry, 

 which is often so sketchily treated in introductory works, the Theory of 

 the Tetrahedron being particularly well explained, as well asUhe sub-section 

 on racemic compounds. 



The second chapter considers the hydrocarbons, and is remarkable for 

 discussing the aromatic compounds immediately after the aliphatic ones, 

 contrary to the usual English method. 



The third chapter is devoted to the functions containing oxygen, and 

 here again we find the author abandoning custom and discussing the phenols 

 immediately after the esters. The subsequent chapters are devoted to 

 Functions containing nitrogen, organo-mineral compounds, heterocyclic 

 compounds, and, finally, a chapter on dye-stuffs. 



Though arranged somewhat differently from English works, the book is 

 developed with a logical sequence well adapted for beginners. 



C. C. R. 



GEOLOGY 



Geology o£ the Mid- Continent OUIields. By T. O. Bosworth, D.Sc, M.A., 

 F.G.S., F.R.G.S. [Pp. xiv + 314, with 8 plates and 24 text-figures.] 

 (New York : The Macmillan Company, 1920. Price i6s. net.) 



The Mid-Continent Oilfield, which comprises an expanse of territory stretching 

 through Louisiana, Oklahoma, and Texas, forms an appropriate subject for 

 geological study. Not only is its production greater than that of any other 

 oilfield — it had supplied almost one-sixth of the world's output to 1919 — 

 but its geological relationships are such that it can be conveniently treated as 

 a unit without a detailed discussion of adjacent fields. In this book the author 

 gives an able summary of the already large volume of work on this region 

 carried out by American investigators. The descriptive parts, which form 

 a concise account of present-day knowledge of the area, are mainly based on 

 the publications of the United States Geological Survey and of the Geological 

 Surveys of the States concerned. 



The introductory chapters contain a useful bibliography and give the 

 history of the development of the region. These are followed by a brief but 

 lucid account of the geological structure and the stratigraphy. The major 

 portion of the book is occupied by a description of the individual accumula- 

 tions, with abundant details both structural and statistical, while the final 

 chapters are concerned with chemical and physical data relating to the 

 character of the oil and with natural gas and the production of gasoline 

 thereform. In the interesting account of the helium which is found in the 

 natural gas of certain districts and was utilised for airships during the war, 

 a few inaccuracies may be noted. It is scarcely correct to state that helium 

 has never been liquefied or that its critical temperature is — 264° C. The 

 accepted figure for the latter is —2677° C, while Onnes succeeded in liquefying 

 appreciable quantities of the gas as early as 1908. 



It is perhaps to be regretted that the book is so much descriptive of the 

 work of others and that so little space is given to general discussion. Prac- 

 tically only the last chapter is devoted to the latter, and even this occupies 

 but a few pages. So far as the origin of the oil is concerned, the author 

 maintains that vegetable matter, imprisoned in the sediments, is the most 

 probable source, while he is also in favour of the validity of " White's Law " 

 regarding the relationship between the devolatilisation of the organic material 

 and the occurrence of oil and gas. A. S. 



