XVI. W. E. COOK. 
Yellow Coloured Sample. 
Crushed sandstone, 729 cubic inches, weighed 37 ‘2ibs. 
Same sand washed, 668°25 __,, 3. oe 
Slime washed from 
729 cubic inches 112 i Ps, 218. ae 
Lost in washing ae xan sie a: OZ 
The 34°2lbs. of washed sand consisted of— 
3°8Ibs. of coarse sand caught on ... 400 mesh sieve. 
706") -,, “standard”, . 900 
23°3 ~,, fine 5, passed through 900 
99 
99 
Lighter Coloured Sample. 
Crushed sandstone, 729 cubic inches, weighed 37°2 Ibs. 
Same sand washed, 658 = * oo Owen 
Slime washed from 
729 cubic inches, 138 3 5 oo” Ge 
Lost in washing oe La hp i 0°08 5; 
The 33°8tbs. of washed sand consisted of— 
3°18lbs. of coarse sand caught on ... 400 mesh sieve. 
6°06 ,, standard ,, eer es!) 0)() x 
24°56 4, fine 55 passed through 900 +8 
That is, only about 20% of the washed material was stan- 
dard sand, or 18 of the original sample. And yet there 
does not appear to be much gain in strength by washing 
crushed sandstone, as the following experiments show :— 
Briquettes made with standard sand, unwashed and 
washed samples of same crushed stone broke as follows: 
Standard. Unwashed. Washed. 
7 days-: 0 ~-213° —6 e 
Dh. az 336 ae 316 a 333 
Thus washed sand proved superior to unwashed by 53+ 
at both 7 and 28 days, and inferior to steadard by 3% 
at 7 days, and less than 1% at 28 days. 
These results are the average of seven tests. Again, 
taking theaverage results of 21 tests of unwashed crushed | 
