Page:Willich, A. F. M. - The Domestic Encyclopædia (Vol. 1, 1802).djvu/513

479&#93; C E M Sooner than mortar, or common stucco, it ought to be worked ex- peditiously in all cases ; and, in stuccoing, should be laid on by- sliding the trowel upwards on it ; and that the materials used with this cement in building, ought, when it is laid on, to be well moistened with the cementing li- cjuor; which is also to bo em- ployed, if necessary, in wetting the cement, or reducing it to a fluid state. When such cement is required to be of the finer sort, ninety-eight pounds of the fine sand are directed to be wetted with the cementing liquor, and tempered with the purified lime and bone-ash in the manner already described ; with this only variation, that fif- teen pounds of lime are to be used instead of fourteen, if the greatest part of the sand be as fine as Lynn sand. This is called, water fevtent Jine-gralnecl, and is to be used in giving the last coating to, or finish- ing, any work intended to in the finer grained stones, or stucco : it may, nevertheless, beappli all the uses of water cement c<. grained, and in a similar manner. Whenever, for any of the al mentioned purposes of pointing, building, &c. a coarser grai 1 and cheaper sand is required, fifty-six pounds of the a arsest band, or of fine rubble well wash- ed, twenty-right of the coarser, and fourteen pounds of the fine sand, are to be mixed toge- ther, and wetted with the gen ieg liquor, as above direct.:.' ; to which fourteen pounds, or some- what Less, of the purified lime, and a similar" quantity of the bone-ash, nre to be added ; and the whole tempered together in the manner already mentioned. When the ce- ment is required to be white, CEM [479 colourless sand, lime, and the whitest bone-ash, are to be select- ed. Grey sand, and grey bone- ash, formed of half-burnt bon :s, are to be chosen for making the cement grey. Other colours may be obtained, by employing coloured sand, or by mixing the necessary quantity of coloured talc in powder, vitreous ormefaijicpowders,or other durable ingredients, usually employ- ed in making paint. This water ce- ment, whether coarse, or fine grain- ed, may be used in forming artificial stone, by making alternate layers of the cement, and of flint, hard stone, or brick, in the moulds of the intended stone, and by expos- ing the masses, thus formed, to the open air, in order to harden. When such cement is wanted for water-fences, two-thirds of the prescribed quantity of bone-ash are to be omitted, and an equal proportion of powdered tarras to be substituted : and if the sand be not of the coarsest sort, more tarras must be added, which should not exceed in weight, one-sixth part of the former. When a cement of the finest grain, and in a fluid form, is required, so that it may be ap- plied with a brush, flint-powder, pounded quartz, or other hard, earthy substance, may be used, in- stead of ?and, but in a smaller quantity, and in proportion to the fineness of the flint, or other powder, so that it shall not amount to more than six times, nor le^s than four times, the weight of die lime. Ac- cording to die greater, or smaller quantity of lime, the cement will be more or less liable to crack, by quiek drying. Where the sand above de- scribed, cannot be conveniently procured, or, where it cannot be washed and sorted, that which bears the greatest resemblance to the