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Geology. — “Examination of specimens of sand from borings done 
at the works of the outer harbour at Scheveningen”. By J. A. 
GRUTTERINK. (Communicated by Prof. J. L. C. SCHROEDER 
VAN DER KOLK). 
H. Worrman Esq. engineer at those works, was kind enough 
to send six specimens of sand to the Geological and Mineralogical 
department of the Polytechnical Institute at Delft. 
‘Those specimens had been taken, respectively at depths of 26.50 M., 
27.50 M.; 28.50 M.; 29.50 M. 3150 M. and 32.50 M. under New 
Amsterdam level. It could however not be guaranteed with perfect 
certainty that the exact order had been observed. 
Stated was that sand, up to 26.50 M., being ordinary dunesand, 
had not been collected. 
The fact that all the specimens contained gross-grained matter 
rendered it impossible to use at once the separatory-funnel. So they 
were sieved ; the sieve having openings of 0.5 cM. 
The examination of the gross-grained matter yielded not much 
of a result. 
In it were found pieces of colourless and of white quartz, up 
to the size of 1 eM., pieces of slate and fragments of shells. 
Granite was not found. 
The percentage of heavy minerals in the finer matter was fixed 
by separating it in a separatory funnel, with the help of Bromoform. 
For the purpose two samples of 5 Gr. of each specimen were taken. 
The percentage was very low: 
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Microscopic examination showed the grains to be rather sharp-edged. 
Amphibole was found in all specimens, even more abundant 
than garnet; only in specimen LV, amphibole was not predominating. 
The size of the grains was also settled microscopically, by moving 
the object-glass parallel with itself across the stage and accepting as 
the size of the grains, not its greatest dimension, but its projection 
on the micrometer. 
So as to avoid passing over a disproportionate number of big 
grains, part of which easily remain out of the field of observation, 
