CYANIDES 1017 



articles. Nothing is subjected to this operation but what is made of cast steel, and 

 has been previously hardened and tempered. 



The polisher consists of a circular piece of wood covered with buff leather, the 

 surface of which is covered from time to time, while in use, -with the crocus of iron, 

 called also colcothar of vitriol. 



The polisher requires to run at a speed much short of that of the stone, or the 

 glazer. Whatever may be its diameter, the surface must not move at a rate exceed- 

 ing 70 or 80 feet in a second. 



CUTTI.E FISH. Mollusca belonging to the class Cephalopoda. The internal 

 calcareous shell of one species (Sepia officinalis) is used as pounce. See SEPIA. 



CYANANXIiXNE. A crystalline body formed by the action of cyanogen upon 

 aniline. See CYANOGEN. 



CYATTATES. The combinations of the various bases with cyanic acid, C-HNO 2 

 (CHWO). The cyanate of potash, C 2 NK0 2 (CWXO), is employed for the prepara- 

 tion of artificial urea. There are two modes of preparing cyanate of potash, both of 

 which yield a good product: the first is that of Clemm, the second -of Liebig. (1.) 

 8 parts of ferrocyanide of potassium and 3 parts of carbonate of potash are intimately 

 mixed and fused, care being taken not to urge the heat too much. The fluid mass is 

 allowed to fall somewhat in temperature, but not to such an extent as to solidify ; 15 

 parts of red lead are then added by small portions. The crucible is now to bo re- 

 heated with stirring, then removed, and the contents poured on to a clean iron plate. 

 (2.) The cyanide of potassium of commerce (prepared by the method described in the 

 article under that head) is to be melted in an iron crucible or ladle, and 3 parts of 

 dry litharge in fine powder are to be added with constant stirring. When the lead 

 has all collected at the bottom, the whole is poured on to an iron plate. The mass 

 obtained by either of the above processes is to be reduced to powder, and boiled with 

 repeated quantities of alcohol, until no more cyanate is extracted. This maybe known 

 when the alcohol filtered from the residue no longer yields crystals of cyanate in cool- 

 ing. C. G. W. 



CYANHYDRXC ACID. See HYDROCYANIC ACID. 



CYANIDES. The combinations of cyanogen with metals or other bodies. It 

 is. remarked in the article HYDROCYANIC ACID that cyanogen, C-N (CUT) is a compound 

 salt-radical, analogous to the halogens chlorine, iodine, and bromine. Like the latter, 

 it unites with metals without the intervention of oxygen, and with hydrogen to form 

 a hydracid corresponding to the hydrochloric, hydriodic, and hydrobromic acids. 

 The cyanides are both an important and interesting class of salts. The most impor- 

 tant is the cyanide of potassium. The latter is formed under a great variety of 

 circumstances, especially where carbonate of potash is heated in contact with 

 carbonaceous matters. The nitrogen to form the cyanide in the greater number of 

 instances is principally, and in a few entirely, derived from the atmosphere. Many 

 chemists have experimented on this subject, and their results are by no means in 

 harmony ; but thus much is certain, that success or failure depends solely upon the 

 circumstances under which the experiments are conducted. It has been shown that, 

 when carbonate of potash mixed with charcoal prepared from sugar (see CARBON) is 

 exposed to a very high temperature in a current of nitrogen gas, the potash in the 

 carbonate is, at times, absolutely converted into cyanide, not a trace of carbonic acid 

 remaining. Experiments of this class, when made with animal charcoal or coal, are 

 less conclusive because those matters contain nitrogen. But even then the amount 

 of cyanogen found is out of proportion to the quantity of nitrogen in the coal or 

 other carbonaceous matters. In fact, it would seem that the presence of a certain 

 quantity of nitrogen in the coal, &c., exercises a predisposing tendency on the 

 nitrogen of the air so as to induce its combination with carbon with greater facility 

 than would be the case if pure carbon were employed. Cyanide of potassium has 

 been found on more than one occasion oozing from apertures in iron-smelting furnaces. 

 In fact, it has been produced in such abundance at one furnace in Styria as to be sent 

 into the market for sale to electro-platers. 



Cyanide of potassium is largely prepared for the use of electro-platers and gilders. 

 The proportions of the materials used are those of Liebig, who first made known the 

 process. The modes of manipulation, however, differ in the details in all laboratories. 

 The following method can bo recommended from the experience of the author of this 

 article as giving a white and good product. It can, moreover, be worked on a very 

 large scale. The ferrocyanide of potassium and salt of tartar are to be separately 

 dried, pulverised, and sifted through cane sieves. The salt of tartar must be free 

 from sulphates. To 8 parts of dry ferrocyanide of potassium 3 of dry salt of tartar 

 are to be added, and the two are to be incorporated by sifting. A largo and strong 

 iron pot is then to be suspended by a chain from a crane in such a position that it 

 can be lowered into the furnace and raised with ease ; there must also be an arrange- 



