1001 



COBALTICYANIDES. 



COCK. 



1002 



radiating; before the blowpipe emits arsenical odours, and tinges 

 borax blue : it occurs in Saxony, Bohemia, Scotland, Cornwall, &c. 

 Analysis by Bucholz : 



Arsenic acid 37-9 



Oxide of cobalt 39-2 



Water 22-9 



100 



Sulphate of cobalt Red vitriol is of a pale rose-red colour, and 

 occurs investing other minerals, in small masses and in stalactites ; the 

 masses are semi-transparent and crystalline ; it is soluble in water, 

 translucent ; lustre vitreous, often dull externally. It occurs among 

 the mining heaps near Hauau and in Salzburg. 



COBALTICYANIDES. [CYANOGEN.] 



COBALTOHYDROCYAKIC ACID. [CYANOGEN.] 



COCCINONIC ACID. An acid of unknown composition, formed 

 by heating euxanthic acid with nitric acid. Its salts of the alkalies are 

 scarlet. 



COCCOGNIDIC ACID. An acid of unknown composition, said to 

 exist in the seeds of the Daphne Gnidivm. 



COCCULIN. [PICBOTOXIN.] 



COCCULUS, a genus of menispermaceous plants, for the botanical 

 descriptions of which see NAT. HIST. Div., comprises among others the 

 C'occuluz pahiiatits, of which the root furnishes calumba, a tonic of con- 

 siderable medical efficacy. 



Calumba acts chiefly upon the mucous membrane of the stomach, 

 and upon the secretion and quality of the bile. It is not however 

 without power over the nervous system, as its efficacy in allaying the 

 vomiting of pregnancy testifies. In diarrhoea, after proper evacuants, 

 and in bilious vomiting, it is superior to all other medicines. The 

 vomiting and nausea of the early months of pregnancy are much 

 alleviated by it ; while the want of appetite, accompanied with general 

 debility, of feeble children, is often removed by calumba along with 

 preparations of iron. 



Dr. Percival states that infusion of calumba will remove the dis- 

 agreeable odour of putrefying ox-gall. Calumba-root, consisting as it 

 does of one-third starch, should be given chiefly in the form of infusion 

 or of tincture. For the preparation of the former cold water alone 

 should be used, as enjoined by the Edinburgh Pharmacopoeia ; this 

 leaves the starch undlssolved, and extracts only the valuable active 

 principles. The infusion made with boiling water spoils more rapidly 

 than probably any other vegetable infusion ; muddiness, followed by 

 mouldiness, taking place very soon, especially if the infusion be 

 allowed to stand on the dregs. Such a fermentable fluid cannot be a 

 proper thing to introduce into an irritable or weak stomach, for which 

 calumba is best suited of all vegetable tonics. Infusion of calumba 

 made with cold water, combined at the moment of using with seltzer- 

 water, i an excellent means of quieting the stomach at the beginning 

 of fevers or bilious attacks. This also restores the appetite frequently 

 lost from over mental exertion, or in the dyspepsia of sedentary 

 literary persons. The common effervescing mixture made with lemon- 

 juice or citric acid and bicarbonate of potash may be substituted, but 

 it is not so good as seltzer-water. 



COCHENILLIN. [CARMINE.] 



COCHINEAL. (French, Cochenitte ; German, Kosriienilje ; Dutch, 

 Conchenilje ; Italian, Cocciniylia ; Spanish, Coclunllla, Grana ; Portu- 

 guese, Cockenilha ; Russia, Koiutend.) Referring to the NATURAL HIS- 

 TORY Division for an account of the insect, we will here simply say a 

 few words concerning the trade in this valuable dye-stuff. Previous 

 to the revolt of the Spanish American provinces almost all the trade in 

 cochineal with the different markets of Europe was carried on through 

 Spain, and chiefly through Cadiz ; but since that event, and the con- 

 sequent removal of the shackles which restricted the trade of Mexico, 

 it ha^ taken a more natural course, and the markets of consumption 

 are supplied with cochineal either direct from the places of production, 

 or from neighbouring stations, to which the article has found its way 

 in the natural course of commerce. Representing a considerable value 

 in a small bulk, cochineal is frequently used, with great convenience to 

 merchants, as'a medium for making remittances, and hence the com- 

 paratively circuitous route by which the greater part of it reaches the 

 places of ultimate consumption. The quantity imported into Great 

 Britain in 1827, was about 320,000 Ibs. ; which rose to 418,000 Ibs. in 

 1835. So rapid was the increase in the next twenty years, that the 

 importation in 1856 amounted to 2,000,000 Ibs. ; and in 1857, to 

 2 500,000 lb. About one-half the quantity' is brought from Hon- 

 duras'. Much is re-exported from England ; but the increase of the 

 trade is mainly due to the extension of dyeing, calico-printing, and 

 colour-making in England. 



COCK, or STOP-COCK, a kind of valve contrived for the purpose of 

 permitting or arresting at pleasure the flow of a liquid through a pipe. 

 The contrivances adopted for this purpose are very various ; but those 

 in most common use consist of a short tube of brass, intersected by a 

 nearly cylindrical plug, capable of being turned on its axis, and so 

 perforated or cut, that, while in one position it completely prevents the 

 JJassage of fluid through the pipe, it may be so turned as to permit the 

 fluid to pass through it, and consequently to flow through the pipe 

 aa though there was no plug to intercept its progress. In addition to 



the differences in the construction of the plug or valve itself, many 

 varieties are required in the form and arrangement of cocks, to meet 

 the various circumstances under which they are applied. Those which, 

 under the name of taps, are employed for drawing off the contents of 

 barrels, simply need to be driven into the holes provided for them, 

 which, before the barrels are broached, are filled with corks to 

 prevent the escape of their contents. This kind of cock, which has 

 been selected for illustration in the following figures, usually termi- 

 nates in a curved nose, or spout, from which the liquor may bo con- 

 veniently received in a jug or other open vessel ; but where it is 

 desired to transfer the liquor from the cask immediately to bottles, the 

 nose is prolonged into a long slender tube, which will enter the neck 

 of a bottle, and obviate the necessity for a funnel. Other kinds of 

 taps are adapted for insertion in metallic cisterns or boilers, or for 

 soldering to the ends of leaden pipes. Fly. 1 represents, in section, 



Fig. 1. 



Fig. 3. 



one of the most common kinds of cock or tap, constructed for inser- 

 tion in a barrel, as represented by the dotted lines at d ; a is the end 

 driven into the barrel, and perforated with a number of small holes, 

 through which the surrounding liquor passes into the interior of the 

 cock, but which, by their minute size, prevent the entrance of foreign 

 bodies which may be floating in it ; b is the nose or spout through 

 which, when the cock is opened, the liquor runs out into the vessel 

 placed to receive it ; c c is a nearly cylindrical plug, rather smaller at 

 the lower than at the upper end, accurately turned, and ground into 

 the opening formed through the cock to receive it, and having a 

 vertical slit or passage formed transversely through its axis, which 

 may, according to the position of the plug, either coincide with or be 

 made to lie across and be totally disconnected from the tubular 

 passage through the cock. This point is more fully explained by Figs. 

 2 and 3, which represent horizontal sections of the plug and its socket 

 or barrel, Fly. 2 showing the plug in the position represented in Fig. 1, 

 in which position it completely intercepts or closes the passage 

 through the cock, and Fig. 3, the plug turned one quarter round, so as 

 to cause its passage to coincide with that of the tube of the cock. 



One of the first improvements on this contrivance which claims 

 notice is that of securing the plug in its place by means of a screw in 

 its lower end, instead of by riveting ; by which arrangement the plug 

 may be readily withdrawn for the purpose of cleansing the cock. Of 

 the many improved cocks in which the common form of the plug is 

 departed from, that represented in fig. 4 is highly ingenious. In this 



the horizontal tube or bore of the cock opens into a vertical cylin- 

 drical chamber or barrel which is lined with a hollow cylinder of cork, 

 and within the cylinder of cork is another hollow cylinder of metal, 

 which constitutes the moveable plug of the cock. Through one side of 

 this hollow plug a circular hole is formed in such a way that in one 

 position of the plug it will coincide with the horizontal passage of the 

 cock, which is continued through the cork lining of the vertical 

 chamber, and thereby allow the liquor to escape by the vertical nose 

 or spout, while turning the plug half round the solid side of the plug 

 is exposed to the passage of the cock, so as effectually to close it. 

 Separate cuts are given to show the transverse section of the plug, 

 Fiy. 5 showing it in the same position as Fig. 4, so as to' close the 

 passage, and Fiy. 6 representing it as turned round to open the passage. 

 This cock is represented without the usual T-shaped handle, the top 



