742 Mr. Charles E. S. Phillips [Feb. 11, 



WEEKLY EVENING MEETING, 



Friday, February 11, 1910. 



George Matthey, Esq., F.R.S., Vice-President, in the Chair. 



Charles E. S. Phillips, Esq., F.R.S.E. M.R.L 



Electrical and other Properties of Sand. 



This material, which flows so freely through my fingers and which 

 may be poured in the manner of a liquid from one vessel to another, 

 is common sand. 



Specimens from various parts of the world are exhibited upon the 

 table. There are sands from the Sahara Desert, from New Zealand, 

 France, Scotland, and several parts of England. I am indebted to 

 Mr. Harrison Glew and Mr. George Draper for many of these. 



There are also bottles of the coloured sands from Alum Bay in the 

 Isle of Wight and Redhill. It may be pointed out at once, that this 

 colouration is merely due to the presence of an adherent layer of 

 oxides or hydroxide of iron, for even varieties which appear under the 

 microscope to contain little or no coloured particles, generally have a 

 trace of iron clin2:in2: to the srrains. 



For instance, a small quantity of white sand from Charlton, having 

 been wetted with strong sulphuric acid before the lecture, will yield 

 on the addition of water a solution containing iron. A few drops of 

 ferrocyanide of potassium give a strong blue characteristic precipitate. 



Further, the so-called black iron sand from New Zealand (for a 

 specimen of which I have to thank Mr. Morison) consists almost 

 entirely of magnetite. If some of it is poured out upon a sheet of 

 paper and brought near to a powerful magnet, you see that the grains 

 fly eagerly to the poles and form large clusters there. This powder, 

 on account of the regularity of its grains, their highly magnetic 

 character and freedom from dust, is particularly useful in the labora- 

 tory for tracing lines of magnetic foi'ce. It is interesting to compare 

 this with the black oolitic sand from Compton Bay in the Isle of 

 Wight, for that is a silicate of iron and therefore non-magnetic. I 

 am indebted to Mr. Colenutt, of Ryde, for the specimen upon the 

 table. 



I wish now to direct your attention to some of the phenomena 

 connected with sand in large quantities, such as are met with upon 

 wide stretches or drifts. 



Blown sand, having been stopped by hedges and grass, gradually 

 accumulates to a mound (Fig. 1) — in some cases with serious con- 

 sequences. Dr. Vaughan Cornish, who has made a special study of 



