232 Reviews — Coal, etc., in the Netherlands. 



A chapter of seventeen pages is devoted to a consideration of the 

 Oil-shales of the Kimmeridge series, which have lately been the 

 subject of much discussion. The observations here recorded are 

 largely founded on the results of borings made by the Department 

 for the Development of Mineral Resources. The possible oil- yielding 

 bed, locally known as the " Blackstone ", forms part of the upper 

 division of the Kimmeridge, and was probably never laid down over 

 much of the distance between Dorset and Cambridgeshire, coming 

 in again as bituminous shales in Lincolnshire and Yorkshire. 

 Numerous analyses are given of samples from Kimmeridge and 

 Corton, in Dorset, and from Donnington-on-Bain, in Lincolnshire. 

 The yield of oil varies from 13 to 39 gallons per ton, and of sulphate 

 of ammonia from 11 to 32 lb. per ton in Dorset, the figures for 

 Lincolnshire being much lower. 



The well-known occurrence of natural gas at Heathfield, in 

 Sussex, is described, as well as other instances met with in borings 

 at Calvert, in Bucks, and near Middlesbrough, which appear to be 

 unimportant. From a statement in the preface it appears that this 

 memoir is to be regarded as an instalment, and that a further 

 publication on the subject of mineral oil in Britain is in 

 contemplation. R H R 



IV. ElNDVERSLAG OVER DE ONDERZOEKINGEN EN UlTKOMSTEN VAN 



DEN DlENST DER RlJKSOPSPORING VAN DeLFSTOFEEN IN NeDERLAND, 



1903-1916. 664 pp. Amsterdam, 1918. 

 fMHIS immense volume contains the final report on the investigations 

 J_ that have been carried on in the Netherlands in search of coal 

 and other useful minerals, chiefly under the direction of 

 Mr. W. A. J. M. van Waterschoot van der Gracht, a geologist well 

 known in England. In 1903 the Government made a grant of 

 3,000,000 gulden for this purpose : the total cost for 25 deep bores 

 and all expenses was about 2,500,000 gulden. Coal-measures were 

 actually reached in three areas : (1) In the Peel district in the middle 

 and north of Limburg coal was proved at a less depth than 1,200 m. 

 over an area of 19,500 hectares; it is estimated that seams of workable 

 thickness contain 1,766, 000, 000 tons, while a further 799, 000, 000 tons 

 below 1,200 m. may possibly be workable in the future, though not 

 immediately available. (2) In the "Winterswijk district in East 

 Gelderland 300,000,000 tons of coal exist at depths not greater than 

 1,400 m., and an enormous amount of rock-salt was also proved. 

 (3) The most important coalfield is, however, in South Limburg, 

 where coal occurs at a less depth than 1,200 m. over an area of at least 

 37,000 hectares. The coal is classified according to its gas content, 

 in the German manner, and the reserves are estimated as follows : — 



Tons. 



Over 35 per cent gas content . . 206,000,000 



35-30 ,, ,, 483,000,000 



30-20 ,, ,, 1,396,000,000 



20-14 ,, ,, 927,000,000 



below 14 ,, ,, 1,541,000,000 



4,553,000,000 



