Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/512

478&#93; 478] CEM brush, 'while boiling. The qmn- tity of oil to be added to the ce- ment must also be increased, or lessened, in proportion as the com- pos! Hon is required to be of a greater or le^s degree of hardness, or softness. The • t£ granted to Dr. Hiugixs, for his invention of a " Wat -r cement or stucco for build- ing, repairing, and plastering walls, &c." The component parts of this cement, are drift or quarry sand, cleansed by washing, and carefully Strained from clay, salts, and cal- careous, gypsous, or other grains hard and durable than quartz; after which it is dried, either in the sun, or on an iron plate in a fur- nace, in the manner of a sand heat. . To this must be added, fourteen pounds of the newest lime-stone that can be procured; and which heats most in slacking, and slacks soonest when duly watered : dis- solves in distilled vinegar with the least effervescence ; leaves as litde as possible of an insoluble residuum, and contains the smallest quantity of clay, gypsous or martial matter. This must be previously sifted in a brass wire sieve, as finely as pos- sible, and slacked, by being re- peatedly immersed in, and quickly drawn out of, a butt fillsd with soft water, till it be made to pass easily through the sieve : rejecting that part of the lime which is too coarse. The patentee directs to continue that process, till as many ounces have been passed through tire sieve as there are quarts of water in the butt. The impregnated liquor, must stand in ; /covered up,unti! it becomes . bca it should be drawn oil* .gh wooden cocks, as fast and .-, as the lime subsides ; being now fit for use. Dr, HtG&xs. CEM nominates this solution, Mc cement* ing liquor. Fifty-six pour.".- of lime, prepared in' the same manner as before, are next to be slacked, by gradually sprinkling on it the cementing liquor, in a close and clean place. The slacked ] >ai : must be iramedi tely lime, if not used instantly, kept in air- tight vessels ; care being taken to reject those pieces which do not pass through the sieve. This richer lime, the Doctor calls purified lime. Bone-ash is then prepared, by grind- ing the whitest burnt bones, which must be sifted mueh finer than that commonly sold for making cupels. The principal materials being thus prepared, fifty-six pounds of the coarser sand, and forty-two of the fine sand, are to be mixed on a large plank of hard wood, placed horizontally, and spread so that it will stand to the height of six inches, widi a fiat surface on the plank. This must be wetted with the cementing liquor, and what- ever superfluous quantities of it will not incorporate widi the sand, must flow off the plank. To the wetted sand are to be gradually added fourteen pounds of the puri- fied lime, tempered in the same manner as fine mortar ; widi this composition are, by degrees, to be mixed fourteen pounds of the bone- ash, and the whole beaten quickly together ; as the sooner, and more perfectly these materials are tem- pered together, and the quicker the cement thus formed is used, the better it will answer the pur- pose. This Dr. Higgins calls tire ■ cement coarse-grained i it is to be applied in building, pointing, plastering, stuccoing, &c. in a si- milar manner with mortar; the principal difference being, that as cement is shorter, and dries much soonet