CIMOLIAN EARTH 803 



of chromate of potash is to bo saturated with weak sulphuric acid, and then to every 

 8 Ibs. are to be added 1 Ib. of common salt, and half a pound of concentrated sul- 

 phuric acid ; the liquid will now acquire a green colour. To be certain that the yellow 

 colour is totally destroyed, a small quantity of the liquor is to have potash added to 

 it, and filtered ; if the fluid is still yellow, a fresh portion of salt and of sulphuric 

 acid is to be added : the fluid is then to be evaporated to dryness, redissolved, and 

 filtered ; the oxide of chrome is finally to be precipitated by caustic potash. It will 

 bo of a greenish-blue colour, and being washed, must be collected upon a filter. 

 H.M.N. 



CHRYSAWIIiINE. See ANILINE YELLOW. 



CHRYSOBERYXi, or Golden Beryl, is composed of alumina 80'2 and glucina 

 19-8 = 100. It is of various shadea of yellowish and light green, sometimes with 

 a bluish opalescence internally. It has a vitreous lustre, and varies from trans- 

 lucent to transparent. Fracture, conchoidal, or uneven. Specific gravity = 3'5 to 3'8. 

 It belongs to the trimetric system. 



This stone, when transparent, furnishes a beautiful gem of a yellowish-green 

 colour, which is cut with facets, unless it be opalescent, in which case it is cut en 

 cabochon. It occurs in the Brazils and Ceylon, in rolled pebbles in the alluvial 

 deposits of rivers ; in the Ural, in mica-slate ; and at Haddam, Connecticut, U.S., in 

 granite, traversing gneiss. H.W.B. 



For varieties of Chrysoberyl, see CAT'S EYE, and CYMOPHANE. 



CHRYSOCOIiIiA. The Greeks gave this name to Borax. It is now applied to 

 the hydrous silicate of copper, a mineral with the composition of silica 34-3, protoxide 

 of copper 45'2, water 20 - 5. It is often mixed with carbonate and oxide of copper. It 

 is found in Chili, in the Lake Superior district, in the copper mines of South Australia, 

 and the West Indian Islands ; also in Cornwall, Saxony, and indeed in most localities 

 where copper-mines occur. Bischof observes, that silicate of copper may be formed 

 through the action of an alkaline, lime or magnesia silicate, on sulphate or nitrate of 

 copper in solution. He also shows that this silicate is decomposed by carbonated 

 waters, producing carbonate of copper. In nature the alkaline silicates are often 

 furnished by the decomposing granite, and the sulphate of copper by the changes 

 which constantly occur in copper pyrites. 



CHRYSOLITE, or Pertilot. The name given to the paler and more trans- 

 parent crystals of olivine, the latter name being restricted to imbedded masses or 

 grains of inferior colour and clearness. It is usually found in angular or rolled 

 pieces, rarely crystallised. The crystals (generally, 8, 10, or 12-sided prisms), 

 belonging to the rhombic system, are variously terminated, and often so compressed 

 as to become almost tabular. They are generally very fragile, and therefore unfit 

 for ornamental purposes. The chrysolite is a silicate of magnesia, with more or less 

 protoxide of iron. An analysis of an oriental chrysolite by Stromeyer gave : silica 

 3973, magnesia 50'13, protoxide of iron 9'19, alumina 0'22, protoxide of manganese 

 0-09, oxide of nickel 0'32 = 99'68. 



As a gem, chrysolite is deficient in hardness and play of colour ; but when the stones 

 are large and of good colour, and well cut and polished, it is made into necklaces, &c., 

 with good effect. From its softness, which is little less than that of glass, it requires 

 to be worn with care, or it will lose its polish. The best mode of displaying the 

 colours to the greatest advantage is to cut it in small steps. To give it the highest 

 polish, a copper wheel is used, on which a little sulphuric acid is dropped. During 

 the process a highly suffocating smell is given out, produced, probably, by the oxida- 

 tion of the copper and the decomposition of the acid. Chrysolite is supposed to have 

 been the topaz of the ancients. It is found near Constantinople ; at Vesuvius ; and 

 the Isle of Bourbon ; at Heal del Monte, in Mexico ; in Egypt ; and at Expailly, in 

 Auvergne.- H.W.B. 



CHRYSOPRASE. An apple-green or leek-green variety of chalcedony, the 

 colour of which is caused by the presence of nickel. It occurs at Kosemiitz, in Silesia, 

 and Belmont's lead-mine, St. Lawrence County, New York. 



This stone was probably the chrysoberyl of the ancients. H.W.B. 



CHRYSOTILE. A fibrous or asbestiform variety of serpentine. 



CHTJTf AIVI. A cement made of shell-lime and sea-sand, commonly used in India. 



CHURCHITE. A hydrated phosphate of protoxide of cerium, found in minute 

 crystals, forming a thin coating on quartz and clay-slate, in a Cornish tin-lode. Mr. 

 C. Greville Williams has detected didymium in churchite. 



CICHORIUM IWTYBUS. See CHICORY. 



CIDER. See CYDEK. 



CXMOXiXAN EARTH. Cimolite (Cimolia, Pliny). This earth is found in the 

 island of Argentiers, the ancient Cimolus, in Bohemia, and some parts of Russia. 

 It has been frequently confounded with fullers' earth, because it has been used for 



