132 Reviews — Prof. Boswell — Economic Uses of Sands. 



also be mentioned, but the study on modern lines of the unconsolidated 

 sediments may be said to date from the classical work of Dr. Thomas 

 on the Trias sands of the West of England. Since then much work 

 of high scientific value has been carried out by Mr. Crook, 

 Mr. Bosworth, and other. As is well known, Professor Boswell has 

 made an extensive study of the mineral constitution of sediments, 

 and when the investigation of sands became a matter of urgent 

 practical importance his knowledge of methods and technique 

 rendered most valuable service. The six publications above cited 

 contain the results of work carried out by him at the instance of the 

 Ministry of Munitions. The first on the list has already been 

 reviewed in these pages and is only included here for the sake of 

 completeness. 



On the outbreak of war a large part of the imported supplies of 

 sand and other similar materials failed, and manufacturers were 

 driven by sheer necessity to inquire into the British resources that 

 might be available to replace them. Sand is used on a large scale 

 for many industrial purposes : in metallurgy it is employed for 

 moulding and as a refractory material ; it is the fundamental necessity 

 of glass-making, and it is also used for building, for filtration, as an 

 abrasive, and for many other pui'poses. The author describes very 

 fully the characters essential for each particular purpose. For glass- 

 making the criterion is purity : a sand adapted for high quality glass 

 should consist as nearly as possible of pure quartz, while what are 

 commonly known as *' heavy minerals " should be in the smallest 

 possible quantity. Iron compounds spoil the colour, while such 

 infusible substances as zircon and rutile produce flaws. Recent 

 research has shown that the presence of a small amount of alumina is 

 not really deleterious, hence felspar up to a certain proportion is not 

 objectionable. Evenness of grain is also important, since it leads to 

 uniform and regular fusion. The requisites for a moulding sand are 

 that it should consist mainly of fairly large grains with a sufficient 

 amount of very fine binding material, thus having a large water- 

 holding capacity. The sands of the Trias best fulfil these require- 

 ments. Other sands are now often employed with an artificial 

 binding material. 



No British glass sands are quite equal in quality to the very best 

 imported kinds, such as those of Eontainebleau and Lippe, but we 

 possess material suitable for even the best kinds of optical glass, 

 while our reserves of sand available for common glass are practically 

 inexhaustible. 



The properties of a sand depend on several factors, of which the 

 most important are chemical and mineralogical composition and 

 texture. The first two are obviously interdependent, and in their 

 investigation the methods devised for geological purposes are of the 

 utmost value. The texture, which is equivalent to size of grain, is 

 determined by mechanical analysis, using the methods devised for the 

 study of agricultural soils. It is clearlj' shown that the state of 

 division is a matter of the greatest practical importance, since it 

 controls to a very large extent the physical properties on which so 

 much of the value of the sand for metallurgical purposes depends. 



