54 
SEA SAND. 
In a series of papers by Prof. Lamplugh, published in the 
Proceedings of the Yorkshire Geological and Polytechnic 
Society, some account is given of the larger boulders found 
along the coast near Flamboroh He enumerates carboniferous 
limestones, carboniferous sandstones, and basalt, as the com¬ 
monest of these, with distinctly smaller proportions of granite 
and quartzite. My impression is that in the Cornelian Bay 
gravel the granite and quartzite are more conspicuous than 
amongst the boulders, and if so, this is probably on account of 
their great hardness. 
We can continue the grinding process begun by the waves 
by rubbing down some sand in a mortar, and washing away 
the finer particles. This still leaves a large proportion of a 
very hard powder, hard enough to scratch glass. This is the 
silica, and if sand is largely silica, it is because silica being 
extremely hard wears down slower than other materials. To 
powder the silica itself, we heat it to redness in a platinum 
crucible and throw it into cold water. After this it is easily 
broken up, and shows under the microscope as sharp angular 
transparent splinters. 
But Scarboro' sand is not all silica : it contains limestone as 
well. Whitby sand and River Ouse sand also contain lime¬ 
stone. But the Bedfordshire and Calais sands are practically 
free from limestone, and so are the sand beds found in the 
ground in several places near York; the yellow sand excavated 
for the Railway Company near the Waterworks; the sand dug 
out to make mimic earthworks on Strensall Common; the 
fertile orange sand from Messrs. Backhouse’s Gardens at 
Cattal, and the beautiful white sand from Huttons Ambo. 
The York Glass Works have made special efforts to secure 
a pure silica sand for making white glass, and are rewarded by 
the sand from Fontainbleau, near Paris, quoted at 99*8 per 
cent, pure silica. 
We have attempted to measure the amount of limestone in 
Scarboro’ sand. The fraction dissolved out by acid is variable, 
and appears to depend on whether that acid is weak acetic 
dissolving carbonates only, or strong, hot hydrochloric, dis¬ 
solving other substances as well. 
