CHARCOAL, WOOD 759 



kept in a well-corked bottle. They are decomposed by water, but dissolve in weak 

 water of potash. On diluting this, decomposition of the salt ensues, with all the 

 chameleon changes of tint ; red, blue, and violet. Sometimes a green solution of this 

 salt becomes red on being heated, and preserves this colour even when cold, but 

 . resumes its green hue the moment it is shaken : it might, therefore, furnish the votaries 

 of St. Januarius with an admirable means of mystifying the worshippers at his shrine. 

 The original calcined mass, in being dissolved, always deposits a considerable quantity 

 of a brown powder, which is a compound of the acid and peroxide of manganese 

 combined with water. Much of the potash remains unchanged, which may be re- 

 covered. 



The permanganate of potash is made by fusing with a strong heat a mixture of 

 equal parts of peroxide of manganese and hydrate of potash, or one part of peroxide 

 and two parts of nitre. The mass is to be dissolved in water, and if the solution bo 

 green, it should be reddened by the cautious addition of a few drops of nitric acid. 

 The clarified liquor is to be evaporated to the point of crystallisation. Even the 

 smallest crystals of this salt have such an intense red colour, that they appear black 

 with a green metallic reflection. In the air they gradually assume a steel-grey hue 

 without undergoing any essential change of nature. A very little of the salt reddens a 

 large body of water. The least portion of any organic matter added to the solution of 

 this salt reduces the permanganic acid to the state of peroxide, which precipitates com- 

 bined with water; the liquor becoming green or colourless, according to circumstances. 

 A more permanent permanganic salt may be made as follows : Melt chlorate of 

 potash over a spirit lamp, and thaow into it a few pieces of hydrate of potash, which 

 immediately dissolve and form a limpid liquid. When peroxide of manganese in 

 fine powder is gradually introduced into that melted mixture, it immediately dissolves, 

 with the production of a rich green colour. After adding the manganese in excess, 

 the whole is to be exposed to a gentle red heat, in order to decompose the residuary 

 chlorate of potash. It is now a mixture of manganate of potash, chloride of potassium, 

 and peroxide of manganese. It forms with water a deep green coloured solution, which, 

 when boiled, assumes a fine red colour, in consequence of its becoming a permanga- 

 nate, and it ought to be decanted off the sediment while hot. By cooling, the per- 

 manganate of potash separates in crystals possessed of great lustre ; but towards the 

 end colourless crystals of chloride of potassium are deposited. See MANGANATES. 



CHATVTO1SITE. A hydrated silicate of alumina and protoxide of iron, occurring 

 as a compact or oolitic iron-ore, at Chamoison, near Saint Maurice, in the Valais. 



CBAMOIVXIIiE FLOWERS. The Anthemis nobilis of Linnaeus. The chamomile 

 grows very abundantly in Cornwall, and some other parts of England. It is culti- 

 vated at Mitcham and in Derbyshire, for the London market. The chamomile is used 

 medicinally, and is employed by some brewers to substitute hops in bitter beer. It 

 would be well if no more objectionable bitter was employed. 



The essential oil of chamomile is remarkable for its blue colour. In a paper read 

 before the Chemical Society by Dr. Piesse, ' On the colouring matter of volatile 

 oils,' this blue body was shown in an isolated state, and was named by the author 

 azidene, 



CHAMPAGNE. See WINES. 



CHANARCIXiLITE. An arsonio-antimonial silver-ore, occurring at Chanarcillo, 

 in Chile. 



CHAPAPOTE. A local name for Mexican asphalt. 



CHARBOXT STTIiFtTRIQUE. This name is applied to the product obtained by 

 treating pulverised madder, either at ordinary or at higher temperatures, with a con- 

 siderable quantity of rather strong sulphuric acid. MM. Persoz and Gauthier do 

 Claubry had shown that the true colouring principles of madder are soluble without 

 alteration in strong sulphuric acid, and it was on this observation, turned to practical 

 account by M. Sobriquet, that the preparation of his charbon sulfurique was based. 

 After the action of the acid has been continued for several hours, the mass is diluted 

 with water, the liquid filtered, and the residue well washed and dried. Charbon sul- 

 furique dyes very strongly, and produces fine colours. 



CHARCOAXi. The fixed residuum of organic substances when they are exposed 

 to ignition out of contact with air. 



WOOD CHARCOAL. As wood charcoal may be regarded as, especially, the repre- 

 sentative of the practically useful charred substances, a description of it naturally 

 precedes that of the other varieties. The earliest plan of coaling wood, as the 

 manufacture of charcoal was termed, and is still called, is carried on as follows : 

 A piece of ground is levelled at some convenient spot in the forest, which is 

 termed the ' hearth ' or ' earth. ' In the centre of this a thick pole or bundle of 

 brushwood is placed, around which the wood is arranged, some of the pieces being 

 laid horizontally and others set up at an inclination; or the wood may be placed 



