43o] C EM the mixture of coarse and fine sand, may be selected ; provided due attention be paid to the quan- tity of lime, which is to be increas- ed, when the sand is fine, and to be diminished, in proportion to its coarseness. In situations where sand cannot be procured, any dur- able stony body, or baked earth, grossly powdered, and sorted in a similar manner, may be substituted bv measure, but not by weight, unless such gross powder be of the gravity. — Sand may be cleansed from softer, lighter, and less durable matter, and from those particles which are too fine, by various methods, preferable in . i;i circumstances to that above d<- nibed. Water may be found naturally ft.*; from fixible gas, selenite, or claj ; and may be employed in- stead of toe cementing liquor- in v. !.:li state, the water will not require so much lime for its pre- paration. Where stone-lime can- not be procured, chalk-lime, or shell-lime, which approaches near- est to stone-lime, may be substi- tuted, in the manner above direct- ed ; with Uiis exception, however, that fourteen pounds and a half of chalk-lime will be necessary, in- stead of fourteen pounds of stone- lime. The proportion of lime may, without inconvenience, be increas- ed, when the cement, or stucco, is to be applied, where it is not liable to dry quickly: on the con- trary, it may be lessened, and the deficiency supplied, with consider- able advantage; by causing an ad- ditional en the cementing liei.or to soak gradually into the
- . aredus matter
of this liquor. .' I ->iic fluid attracted from the ■atmosphere, may fill and stren .. ; e CEM ship. The powder of almost eve- ry well-dried, or burnt, animal matter, may be substituted for bone-ash , and several earthy pow- ders, especially the micaceous, and the metallic, as well as the calca- reous ashes of mineral fuel, and the elixated ashes of various vege- tables, the earth of which cannot, by burning, be converted into lime, will, in some measure, answer the purposes of bone-ash : in short, the quantity of the latter may be less- ened, without injuring the cement, particularly in those circumstances which admit of a diminution of lime, and whore the cement is not liable to dry quickly. For inside work, it will be very use- ful to mix hair with the cement. The last patent, which we shall notice, was granted in November, 1800, to Mr. John Baptist De- nize, chemist, for a cement, ap- plicable to various purposes. The basis of this is petroleum, or rock oil, in any form ; in which a small portion of sulphur is dissolved, by melting j to which is added any kind of vitrescible, earthy matter, such as clinkers, and scorice, from iron, or glass furnaces j puzzolane, or any volcanic ashes, &c. These are to be powdered, and stirred in- to the melted sulphur-oil, till the whole becomes of such a consist- ence as to be easily spread with a trowel, and does not adhere to the fingers, when cool. This cement is firm, durable, and impervious to moisture. Those of our readers, who may be desirous of additional informa- tion, relative to this interesting subject, wc refer to the translation of ivl. Loriot's " Practical Essay on Cement and Artificial Stone," (Svo. is. -6d. Cadell, 1/74); and to Dr. Higgins's (< Experi- ments
