466 Notices of Memoirs—Dr. Boswell—Glass Sands. 
Discussion on the Utilization of Waste Lands, introduced by Professor 
F. W. Oliver, and including the following short papers :— 
P. A. Martineau.—The Afforestation of Pit Banks: Discussion. 
Professor F-. W. Oliver.—Maritime Wastes. 
Professor W. B. Bottomley.— Waste Moorlands. 
Professor J. Lloyd Williams.—Reclamation of Peaty Soils in 
‘Carnarvonshire. 
Dr. W. &. Smith.—Utilization of Northern Mountain and Heath 
Land. 
Il.— Some GrotogicAaL CHARACTERS OF SANDS USED IN GLASS 
Manouracrure. By P. G. H. Boswetr, A.R.C.Sc., D.Se., F.G.S. 
T a time when it is necessary to know the extent and value of 
A our national resources of sands suitable for various industrial 
purposes, including glass manufacture, it is especially desirable that 
we should realize the particular properties of such sands and the 
geological conditions under which the deposits occur in the field. 
1. In chemical composition, for all general purposes of glass- 
making, the sand should contain a very high proportion of silica, if 
possible over 99 per cent. ‘he percentage of iron (estimated at 
Fe, O,) should be as low as possible, For optical glass, table-ware 
(‘crystal’), etc., it should not rise above 0°5 percent; for laboratory- 
ware, globes, aud all second-grade glass-ware, a percentage up to 
0-02 is permissible; for plate and window-glass and good white 
bottle-glass, the proportion may reach 0°3 or 0:4 per cent; and for 
rough bottle-glass and other similar work, a limit of 2 per cent may 
beadmitted. For refractory glass, such as that used for thermometers, 
gauges, certain laboratory-ware, etc., it is an advantage to find a 
sand bearing 4 per cent or more of alumina. Unfortunately, most 
British sands bearing alumina carry also iron and other undesirable 
impurities. Other bases such as lime, magnesia, titanium, and 
alkalies, should, if present at all, exist only in negligible quantities. 
In the analyses the loss on ignition should also appear; it yields an 
indication of the amount of water and organic substances present. 
The latter are not objectionable as they usually ‘burn out’. 
The analysis of one of the best British glass-sands, a sample of 
Lower Greensand from Aylesbury, indicates $iO,, 99°80 per cent ; 
Al, O3, 0°32 per cent; Feg Og, 0°03 percent; loss on ignition, 0°22 
per cent; total, 100°37 per cent. With this may be compared a 
well-known German glass-sand from Lippe: 810g, 99°88 per cent; . 
Aly Og, 0°18 per cent; Fes O3, 0°02 per cent; loss on ignition, 0°21 
per cent; total, 100-29 per cent. 
2. ¥or all but the highest quality glass, where the cost of crushing 
the raw material to a fine even state, with suitable subsequent 
treatment, is not prohibitive, the mechanical composition is of the 
utmost importance. The sand used should, if possible, be perfectly 
eraded, that is, it should be composed of grains all of the same size. 
Such perfection of grading is not attained as a result of natural 
agencies; the best-graded natural deposits contain over 90 per cent 
of grains of one grade, which, for glass-making purposes, is preferably 
