STATE GEOLOGIST. 340 
Amount of Water.—The amount of water used in making the mortar 
has considerable influence on the resulting strength, as is indicated by 
the following series of tests made by E. S. Larned :* 
eens Tensile strength neat cement. Pounds per square inch. 
pe eeeenwe eee eter los con 
meee eee e ee eel al | astas b months | mocha. i moneee 
; eae / ; 
Guns | ip | qa | au | en | Ge | cae | on F Zen | 787 
is 16 | 29 | 297 | 303 | 750 | 973 | 1008 | 735 | 816 
& 1 | SO | B85 | B80 | Cho | ee) eel | RP as 
a a 1a | am | oe | eo 1 Ge | mG | Gn | are 
i DD | 3 | 2B | Tel BAG | Cae | ass | GO | eee 
es ot | 37 | O12 || Tey | SSO | CAD | GAe | Ge | wae 
Atlee oo.) 98 13.1) S70 |) 366 775 59 | 1067 | 892 | 832 
a Mo 18 | soe |) 202 F Wao | eon | Oe Bae Fei 
1G. || 22) Bar | SEB GO I OR | Bae | eas | yee 
( | 78 | i | S383] S08 | By@ | yee | 7RR | ws ae 
ee 30 | S&B | FOR | 2B | sO | mS | no | BA | aE 
DO oe Seam GG) eeos4 816490) | 73Ie 8643. | G04 
Boa DA) 1a | one M2 | Si | GL) GOR | CO | Be 
The proper amount of water to be used with each cement must be 
determined by experience. 
Crushing Machines.—The crushing test is ordinarily performed on a 
very elaborate and expensive machine which can be employed only in 
large laboratories and testing stations. 
However, there are certain machines on the market that permit of 
carrying out crushing tests, such as the Amsler-Laffon, which are not 
too expensive and still give good results. The machine mentioned is 
hydraulic in principle and uses as liquid heavy glycerine which does not 
leak between the piston and the cylinders. Pressure is applied by movy- 
ing the piston by means of a geared crank and compressing the liquid. 
The pressure is indicated by a mercury manometer. In principle as well 
as in design this machine is,a most excellent apparatus, eliminating the 
usual errors of hydraulic machines of this kind most completely. It de- 
*American Society for Testing Material, July, 1903. 
A 
