716 CARBO.HYDRIDE 



bevel ring e. A mode of shifting these is essential ; because the two toothed rings, 

 and their driving -worm and pinion, give different speeds, and, of course, cannot be 

 both in operation at the same time. 



The worm of the shaft / being placed in gear with the teeth of the ring g, on 

 applying rotatory power thereto, by means of winches 

 424 attached to the ends of the shaft, the barrel or body of 



the capstan will be made to revolve with a slow motion, 

 but with great power ; and thus two men at the winches 

 will do the same work as many men with capstan bars 

 in the ordinary way. 



If a quicker movement than that of the endless screw is 

 desired, then the driving power may be applied by a winch 

 to the axle g of the bevel pinion, that pinion being put into 

 gear with the bevel ring e, and the endless screw with- 

 drawn. It should, however, be hero remarked, that the 

 patentee proposes to employ two short axles g, placed opposite to each other, with 

 bevel pinions acting in the bevel-toothed ring, though only one is shown in the 

 figure to. avoid confusion. He also contemplates a modification of the same con- 

 trivance, in which four short angles g, placed at right angles, with pinions taking 

 into a bevel ring, may be employed, and made effective in giving rotatory motion to 

 the barrel of a capstan by means of winches applied to the outer ends of the axle, 

 and turned by the labour of four men. 



CAPUT MORTinritX. A term employed by the alchemists to express the resi- 

 duum of distillation or sublimation, the volatile portions having been driven off. 

 CARATURA. A red dye stuff: see CHICA, RED. 



CARAlVIEIi. Burnt or dried sugar, used for colouring spirits and gravies. It is a 

 black, porous, shining substance, soluble in water, to which it imparts a fine dark 

 brown colour. The French are in the habit of dissolving the sugar, after it has been 

 exposed for some time to a temperature sufficiently high to produce the proper colour, 

 in lime-water : this is sold under the name of ' colouring.' 

 CARAPA Oil.. See CKAB OIL. 



CARAT. The term carat is said to be derived from the name of a bean, the pro- 

 duce of a species of Erythrina, a native of the district of Shangallas in Africa, a famous 

 gold-dust mart. The tree is called kuara, a word signifying ' sun ' in the language of 

 the country, because it bears flowers and fruit of a flame-colour. As the dry seeds 

 of this pod are always of nearly uniform weight, the savages have used them from 

 time immemorial to weigh gold. The beans were transported into India at an 

 ancient period, and have been long employed there for weighing diamonds. The 

 carat of the civilized world is, however, an imaginary weight, consisting of four nominal 

 grains, a little lighter than four grains troy (poids de marc). It requires 74 carat 

 grains and ith to equipoise 72 of the other. The diamond carat, though containing 

 4 diamond grains, is equal to only 3| grains Troy. 



It is stated that the karat, a weight used in Mecca, was borrowed from the Greeks, 

 and was equal to the 24th of a denarius or denier. The Encyclopedists thus explain 

 the carat : ' The weight that expresses the fineness of gold. The whole mass of 

 gold is divided into 24 parts, and as many 24th parte as it contains of pure gold it is 

 called gold of so many carats. Thus gold of twenty-two parts of pure metal is gold 

 of twenty-two carats. The carat of Great Britain is divided into four grains ; among 

 the Germans into 12 parts; and among the French into 32.' Among assayers, even 

 in this country, the German division of the carat is becoming common. 



CARAWAY SEEDS. The fruits, commonly called seeds, of the Carum Carui, 

 an umbelliferous plant. They are used for flavouring cordials. The oil of Caraway 

 is employed to correct, by its aromatic properties, the nauseating and griping qualities 

 of some medicines. 



CARBAMXC ACID. The combination of gaseous ammonia with carbonic-acid 

 gas produces a white substance formerly called anhydrous carbonate of ammonia, but 

 now recognised as a salt of carbamic acid. This carbamate of ammonia readily 

 combines with water, and passes into normal carbonate of ammonia. 



CARBAMIDE. A white crystalline powder obtained by the action of gaseous 

 ammonia on phosgene gas, or oxychloride of carbon. 

 CARBAZOTXC ACID. See PICRIC Acn>. 



CARBIDES. A term synonymous with carburets. Thus, cast-iron being a 

 combination of iron and carbon may be called a carbide or carburet of iron. In like 

 manner the hydrocarbons are sometimes termed carbides of hydrogen. 



C ARBO-HYDRATES. Organic compounds containing carbon and the elements 

 of water ; such as starch and cellulose. 

 CARBO-HYDRXDE, commonly Hydrocarbon. A term used to denote those 



