426 Reviews — Central Scottish Coalfield. 



a scheme for identifying them by the characters revealed under the 

 microscope. 



After a full historical account of the work of previous writers — 

 not a great number — the author carefully describes the comparatively 

 simple apparatus required for the preparation of suitable polished 

 sections, and gives a list of the reagents which are used in 

 microchemical work. The opaque minerals are divided into three 

 main groups : coloured, white, grey. Difference in hardness as 

 compared with a steel needle and the behaviour when treated with 

 certain reagents are made use of for further subdivisions until the 

 mineral species in question is finally run down. The white group 

 is a large one, and for subdivision reliance is placed upon the tint as 

 compared with the standard white of galena. Mr. Murdoch asserts 

 that after a little practice the eye can unerringly appreciate such 

 slight differences as greyish white, pinkish white, bluish white, and 

 creamy white. A correct determination at this stage is important, 

 since otherwise much time may be lost in following a false trail. 

 The arrangement of the copious tables is the most remarkable feature 

 of the book. By an ingenious use of cutting or "tabbing" the 

 upper and side edges of the leaves reference to the tables is rendered 

 easy, and to prevent mistakes the order of the tests is printed on 

 the upper left-hand corner of the left-hand page. 



This is, in short, a book that should be in the hands of every 

 metallurgist or mineralogist. 



II. — The Economic Gteologx op the Central Coalfield of Scotland. 

 Description of Area V (Glasgow East, Chryston, Glenboig, and 

 Airdrie). Mem. Geol. Survey Scotland, pp. viii + 146, with 

 13 plates and 5 figures. 1916. Price 4s. 6d. 

 f 1 1BIIS memoir is the first to be published of a series intended to 

 JL provide a description of the economic geology of the central 

 coalfield of Scotland. The area dealt with includes a large part of 

 the city of Glasgow, and extends eastwards beyond Airdrie, with 

 a tongue projecting beyond Longriggend into Linlithgowshire. The 

 strata included all belong to the Carboniferous system, overlain in 

 places by a considerable thickness of superficial deposits, both glacial 

 and post-glacial, and there are a good many intrusive sills and dykes 

 of dolerite, often containing analcime. As is well known, coal is 

 largely developed in Scotland in the Lower Carboniferous, while the 

 upper part of the Upper division is barren. 



The memoir contains a detailed description of the coal-bearing 

 strata of the district, again subdivided into four areas. This 

 information is very largely derived from the records of mine-shafts 

 and borings. Erom the manner in which it is presented it is evident 

 that the memoir is intended mainly for the "practical man ", since 

 these portions are written in a language unintelligible to the ordinary 

 scientific geologist. Among the descriptive petrological terms we 

 find for example : stone, rib, metal, fakes, blaes, sclit, and daugh, 

 without any explanation, while from the context it can be gathered 

 that in the local patois " float " means a sill. 



