724 CARD, CARDBOARD 



much denser than common air, can be pumped out of any place containing it. Milk 

 of lime quicklime mixed with water may be used with advantage to purify the 

 nir of a sunk apartment, by its affinity for, or power of absorbing this aerial acid. 



In the actual condition of the atmosphere, from 4 to 6 volumes of carbonic acid 

 exist in every 10,000 volumes of air. 



This acid gives the fresh and pleasant taste to spring-water and to all fermented 

 drinks. Champagne and bottled beer owe their sparkling properties to carbonic acid 

 gas generated by fermentation after the liquid has been bottled. 



Many springs are very highly charged with this acid, and form a sparkling beverage, 

 as Seltzer water (Selterswasser) and the like. Large quantities of similar water are 

 made artificially in this country, and sold under the names of Soda Water, Aerated 

 Water, &c. See Watts's ' Dictionary of Chemistry.' 



CARBONIC ANHYDRIDE. See CARBONIC AciD. 



CARBONIC OXIDE. (Symbol, CO ; Atomic weight, 14). This gas is known in 

 modern chemistry as carbon monoxide or carbonous oxide. Carbonic acid is readily 

 deprived of half its oxygen at a red heat by charcoal and other deoxidising substances, 

 and so reduced to carbonic oxide. 



This gas is presumed to contain two volumes of carbonic vapour and one volume 

 of oxygen condensed into two volumes, so that its combining measure is two volumes. 

 Carbonic oxide is 14 times heavier than hydropren. It is very fatal to animals, and 

 when inspired in a pure state almost immediately produces coma. It has never been 

 liquefied. It is easily kindled, and burns with a pale blue flame like that of sulphur, 

 combining with half its volume of oxygen, and forming carbonic acid, which retains 

 the original volume of the carbonic oxide. This combustion is often witnessed in a 

 coke or charcoal fire. The carbonic acid produced in the lower part of the fire is 

 converted into carbonic oxide as it passes up through the hot embers, and afterwards 

 burns with a pale-blue flame where it meets the air. Graham. 



Carbonic oxide plays an important part as a reducing agent in many metallurgical 

 operations. 



CARBONIFEROUS LIIVIESTONE, or MOUNTAIN X.IIVXESTONE. A 

 sub-division, of the Carboniferous System, which yields some of the finest British 

 marbles, such as those of Derbyshire and Bristol. The same limestone in Ireland is 

 also rich in marbles. Lead-ore is common in the Carboniferous Limestone of Derby- 

 shire, Yorkshire and Cumberland, and red haematite in that of Ulverston and 

 Whitehaven ; whilst in the North of England and in Scotland the Carboniferous 

 Limestone series contains interstratified beds of coal ; indeed, a large part of the 

 workable coal of East and Mid-Lothian is referable to this series. 



CARBONIFEROUS SYSTEM. That geological formation which, in order of 

 time, succeeds the OLD RED SANDSTONE, and is succeeded by the PEEMIAN SYSTEM, 

 although in the absence of that system, they may be overlaid by rocks of still later 

 geological age. The carboniferous system comprehends : 



The Lower Limestone Shale : The Carboniferous or Mountain Limestone : Yoredale 

 Socks ( Upper Limestone Shale) : and the Coal-Measures, Lower, Middle, and Upper. 



CARBON PRINTING. See PHOTOGBAPHY. 



CARBUNCLE. A term applied to the garnet when cut with a convex face 

 (en cabochon). This gem was much prized by the ancients, and in high repute during 

 the middle ages, from its supposed mysterious power of emitting light in the dark. 

 Bcnvenuto Cellini affirms, in his treatise on jewellery, that he had seen the carbuncle 

 glowing like a coal with its own light. 



' The garnet was, in part, the carbunculus of the ancients, a term probably also 

 applied to the spinel and oriental ruby. The Alabandic carbuncles of Pliny were so 

 called because cut and polished at Alabanda. Hence the name Almandine now in 

 use. Pliny describes vessels of the capacity of a pint formed from carbuncles, non 

 claros ac plerumque sordidos ac semper fulgoris horridi,' devoid of lustre and beauty 

 of colour, which probably were large common garnets.' Dana. 



CARBURETS. Compounds of carbon, now called Carbides. 



CARBURETTED HVDROCEN. A compound of carbon and hydrogen. 

 Marsh-gas or fire-damp is frequently called Light Carburetted Hydrogen. See GAS- 

 COAX, and consult Watts's ' Dictionary of 'Chemistry.' 



CARD, CARDBOARD, called also Pasteboard, from the circumstance that 

 several sheets of paper are pasted together to form the board or card, which is then 

 subjected to a very great pressure between rollers. 



A patent machine for cutting cards was invented by Mr. Dickinson. It consists of 

 a pair of rollers with circular revolving cutters, the edges of which are intended to 

 act against each other as circular shears ; and the pasteboards, in passing between 

 these rollers, are cut by the circular shears into cards of the required dimensions. 

 These rollers are mounted in suitable standards with proper adjustments, and are 



