CYDER 1019 



bianco to sapphires ; the hardness, however, is considerably less, It is notable that 

 the hardness of cyanite varies in different faces of the same crystal the old name 

 Disthcne (Sis, twice ; trQevos, strength), having reference to this unequal resistance 

 which the crystal offers in two different directions. 



CYANOGEN. C 2 N (CM 1 ). A compound salt-radical, analogous in its character 

 to chlorine and the other halogens. It was the first body discovered possessing the 

 characters of a compound radical, and the investigations made upon it and its deri- 

 vations have thrown more light upon the constitution and proper mode of classifying 

 organic substances than any other researches whatever. In consequence of its acting 

 in all its compounds as if it were a simple body or element, chemists generally have 

 acquired the habit of designating it by the symbol Cy. Like the haloids, it combines 

 with hydrogen to form an acid, and with metals, without the necessity for the presence 

 of oxygen. Fora few illustrations of , its analogies with chlorine, &c., see HYDRO- 

 CYANIC ACID. In the article CYANIDES several of the conditions under which it is 

 formed have also been pointed out. The modern French chemists of the school of 

 Gerhardt very justly regard cyanogen in the light of a double molecule, thus Cy Cy, 

 or C 4 N 2 . The reason of this is because most of the phenomena of organic chemistry 

 are more easily explained by the use of four-volume formulae than any others. This 

 latter mode of condensation has been shown by M. Wurtz, in his admirable work on 

 the compound radicals, to undoubtedly exist in the case of radicals belonging to the 

 strict hydrogen type, not as ethyle and its homologues ; and numerous theoretical and 

 experimental results are in favour of the supposition that all radicals in the free state 

 are binary groups. 



If we assume the truth of the above hypothesis, we shall regard cyanogen in the 

 free state as a cyanide of cyanogen, analogous to hydrocyanic acid, which is a cyanide 

 of hydrogen. 



Cyanogen may very conveniently bo prepared by heating cyanide of mercury in a 

 retort of hard glass. A considerable quantity of the gas is given off, but a portion 

 remains behind in the state of paracyanogen. The latter substance is a black matter, 

 the constitution of which is by no means understood. It has, however, the same 

 composition in the hundred parts as cyanogen itself, and is therefore isomeric with it. 



Cyanogen is a colourless combustible gas, with a sharp odour. Its density is 1'81. 

 theory requires for two volumes 1 - 80. If cooled to a temperature of between 13 

 and 22 F., it liquefies into a transparent, colourless, and very mobile fluid, having 

 a specific gravity of 0'866. A little below 22 the fluid congeals to a mass resembling 

 ice. The flame of cyanogen is of a pale purple or peach-blossom colour. 



Some of the properties of cyanogen are very remarkable, and quite distinct from 

 those of the true halogens. For instance, it combines directly with aniline to produce 

 a body having basic properties. The latter is callted Cyaniline or Cyananiline, and 

 is formed by the coalescence of two molecules of cyanogen with two of aniline, tho 

 resulting formula being consequently C 28 H 14 N 4 (C^H 14 !^ 4 ). There are a variety of 

 singular compounds produced by the action of cyanogen and its halogen compounds 

 upon aniline ; they have been studied with remarkable skill by Hofmann. C.G.W. 



CYAXTOSE or Cyanosite. Native sulphate of copper. 



CYANURIC ACID. When cyanate of ammonia is heated it passes into urea; 

 and urea by further heating may be converted into ammonia and cyanuric acid. This 

 acid may also be prepared by the action of sulphuric acid on melam. Cyanuric acid 

 contains C 6 H S N 3 8 (C'H'WO 3 ), and at a very high temperature may be resolved into 

 three molecules of cyanic acid. 



CYDER ( Cidre, Fr. ; Apfelwein, Ger.) : the vinous fermented juice of the apple. 

 The ancients were acquainted with cyder and perry, as we learn from the following 

 passage of Pliny the naturalist : ' Wine is made from the Syrian pod, from pears and 

 apples of every kind.' (Book xiv. chap. 19.) The term cyder or cidre in French, at 

 first written sidre, is derived from the Latin word sicera, which denoted all other fer- 

 mented liquors, except grape- wine. Cyder seems to have been brought into Normandy 

 by the Moors of Biscay, who had preserved the use of it after coming into that country 

 from Africa. It was afterwards spread through some other provinces of France, 

 whence it was introduced into England, Germany, and Russia. It is supposed that 

 the first growths of Normandy afford still the best specimens of cyder. Devonshire 

 and Herefordshire are the counties of England most famous for this beverage. 



Strong and somewhat elevated ground, rather dry, and not exposed to the air of the 

 sea, or to high winds, are the best situations for the growth of the cyder apple. The 

 fruit should be gathered in dry weather. The juice of apples is composed of a great 

 deal of water ; a little sujrar analogous to that of the grape ; a matter capable of 

 causing fermentation with contact of air; a pretty large proportion of mucilage, with 

 malic acid, acetic acid, and an azotised matter in a very small quantity. The seeds 

 contain a bitter substance and a little essential oil ; the pure parenchyma or cellular 



