Revieius — Materials required in Glass-making. 475 



papers by members, on the fixation of atmospheric nitrogen and on 

 saccharine respectively. 



The first part of the third volume of the Sastmgs and Ea&t Sussex 

 Naturalist, the organ of the Hastings and St. Leonards jS^atural 

 History Society, also shows evidence of much activity on the part of 

 that Society. It contains two papers of geological interest. The 

 first of these, by Mr. Anthony Belt, is entitled "Prehistoric 

 Hastings", and comprises a very full account of the geological 

 history of that interesting district, from the Wealden to the Eoman 

 occupation. Most space is devoted to the later phases, and special 

 attention is paid to the history and development of man, as is only 

 natural in a district so near to the home of Eoanthropus Datvsoni. 

 Another valuable contribution is a paper on the Brighton Rubble- 

 Drift formation, by Mr. E. A. Martin. This, though short, gives 

 a very good description of this peculiar and interesting formation, 

 illustrated by phot graphs. 



The annual report of the Norwich Castle Museum for 1917 shows 

 that the Museum was the centre for the dissemination of much 

 useful information, and the fact that it was visited by no less than 

 132,751 persons shows that it has succeeded in fostering a widespread 

 interest in historical and scientific subjects. 



IV. — British Supplies of Potash Felspar, consideeed from the 

 Glass-making Point of View. By Professor P. G. H, Boswell, 

 D.Sc, F.G.S. Trans. Soc. Glass Technology, vol. ii, pp. 35-71, 

 with 1 plate and 4 figures. 1918. 



POTASH-FELSPAR, for use in the pottery and glass industries 

 should satisfy the following requirements: — 

 1. High content of potash, if possible more than 10 per cent and 

 certainly not less than 8 per cent. 



■ 2. Low content of soda ; preferably none and certainly not more 

 than 2 per cent. 



3. Low content of quartz, not more than 5 per cent for the best 

 pottery, and not in excess of 20 per cent for inferior pottery. In 

 glass-making the quartz does no harm, but it can be bought at 

 a lower rate tliau felspar. 



4. The amount of iron oxide should be small, and in the best 

 pegmatites the percentage falls below 0*1. 



5. Lime should not exceed 0*5 per cent. 



6. The rock must be fresh, or there will be a considerable loss of 

 potash owing to kaolinization of the felspars. 



It may be mentioned that 13 and 9 per cent of potash correspond 

 respectively to 77 and 53 per cent of microcline or orthotdase, and 

 3 and 1 per cent of soda to 25 and 9 per cent of alhite. 



More or less workable deposits of potash-bearing felspar in the 

 form of pegmatites occur in many localities in the British Isles. 

 These are Tresayes, Trelavour Downs, Kernick, and Luxulyan in 

 Cornwall; in Sutherland, between Lochs Laxford and Inchard, 

 between Durness and Eireboll and near Overscaig, Strontiau 



