54- Results of Mr. White's Experiments on Cements. 



Cohesive 



Strength per 



^square Inch. ^ 



lbs. mean. 



Cement in bars, age 94 days, 1 dry 2101 



2 var 618 V 380 



3 wet 312S 



age 187 days, 1 dry 534 "^ 



2 var 708V519 



3 wet 336 j 



Meanofthedry 433 



variable ... 562 



wet 288 



With salt-water 924. 



With 51 per cent, of water 330 



With 64 do 215 



3 parts cement, 2 parts sand 455 



1 part cement, 1 part brickdust ... 312 



Bricks. — 3 parts cement, 2 parts sand, 6 months 375 



3 2? 362 



All cement 9 months 360 



Paving bricks, best sort 253 



seconds 194, 



Common building bricks, London* ... 4.3 



Common bricks, Soho 412 



Brick cylinders laid in cement 27 



-■ in cement and sand gg 



48 



53 



Brick piers laid in cement, 2 parts ;'^ 



rough lime, 1 part; > 1 month. 41. 



sand, \\ part; J 



pozzolano, 3 parts 1 „ , 



T\ 1 • r 1 , r 6 weeks. 7 

 Dorking lime, 1 p' J 



pure cement 21 



pozzolano, 1 ; stone-lime, 1... gi. 



Atkinson's cement, 1 ; sand, 1 25i- 



Ditto 491. 



cement, 4; lime, 1 17 



The apparent deficiency of strength in these experiments 

 probably arose from the position of the resultant and strain 

 in being on one side instead of in the middle of the piers ? 



• Stourbridge fire-bricks have a strength of "J^d pounds per square inch. 

 The bricks I used at Greenwich Well were made at Fenny Stratford, and 

 would support 715 pounds per square inch, equal to the strength of York- 

 shire stone. 



