In works where it is important to have a first-class cement the specifications should read about as follows, and all brands submitted should be carefully tested, and those which do not meet the requirements should be rejected:
Specification. - The whole of the cement shall be Portland cement of the very best quality, weighing not less than no pounds to the striked bushel, ground so fine that not over 10 per cent, will be rejected by a sieve of 2,500 meshes per square inch (No. 35 wire) and capable of maintaining a breaking weight of 350 pounds per square inch after hardening one day in air and six days in water, and shall show no cracks or blotches when left under water twenty-four hours.
This is a patented preparation of cement similar in character to Portland cement, made from a limestone of hydraulic properties. It is hydraulic in character, but, unlike Portland or Rosendale cement, does not stain marble, limestone and other porous stones when used in setting them, and therefore is especially desirable for setting such stones.
For setting large stones mix 1 part by volume of lime paste to 4 parts of the cement; to retard the setting of the cement until the stones are well bedded.