CANNEL COAL. - In polishing flat works of this material, such as inkstands, water of ayr stone in the stick is 1st used with water; 2ndly, charcoal dust an( soft soap on a flannel; and although 3rdly, for fine works rottenstone on the hand or flannel have been used, it is better to continue the second process until the completion, adding only additional soft soap with water as lubricator. For the working of cannel coal, see vol. 1, p. 162.
For objects turned in the lathe, the water of ayr stone is superseded by emery paper.
The Lapidary works Cannel Coal just as he would Alabaster; see Article 3 under that head.
CAP. - A term used by many of the Sheffield Cutlers to designate wooden wheels, capped or surrounded with a ring of metal to constitute laps, the edges only of which are used, see Wheels, articles 37 to 47, where their construction and application are described.
CARBON, when highly crystallized, as in the diamond, is the hardest substance in nature, and cuts all others. Next in hardness to the diamond are those mineral substances having for their bases alumina, silex, and the metallic oxides of iron and tin. See also the articles on Diamond and Charcoal.
CARBUNCLE. - The stone that is considered to have obtained this name, in ancient as well as in modern times, is the Almandine, or Precious Garnet of mineralogy; it is usually polished en cabochon, or with a rounded surface without facets, after the general manner of oriental jewellery, and is worked like Carnelian, as described in the following article.
CAT'S-EYE, a mineral consisting of quartz enclosing amianthus or asbestos, and thence possessing the property emphatically described by the French as chatoyant; the cat's-eye is polished just like Agate or Carnelian.
CHARNLEY FOREST STONE, See Hone Slates, article 2.
CHRYSOLITE or PERIDOT, a yellow gem, sometimes tinged with green or brown, that is obtained principally from the Levant. It possesses a peculiarity, inasmuch as although it is slit and facetted just like Carnelian, it can scarcely be well polished, otherwise than by means of a copper lap with rottenstone, a few drops of sulphuric acid being used instead of water to moisten the rottenstone.
CHRYSOPRASE, a variety of Chalcedony, of an apple green colour, and semi-opaque, which is much prized by jewellers. It is cut and polished after the mode of Carnelian, and frequently of a convex form, or en cabochon.
CLAY, see Loam.
CLOTH is extensively used as a vehicle for polishing powders of all kinds; woollen and felted cloths are the most in requisition. Some of the felted cloths used for marble, glass, etc, and which are called nap, are upwards of half an inch thick. Thinner cloths, such as the stout cloths used for great coats and for the blankets of printing presses, are also employed, especially when discarded from their original purposes, and also ordinary woollen cloth, including the list, or selvedges, and so on.
Old worsted stockings are used in many trades; linen and cotton cloths and rags are also employed, but, from being thinner, are less generally used than woollen cloths. Cloth Wheels, see Wheels, articles 61 to 64.