CARBONIC ACID. 



CARDOON. 



carbonate it occasions upon the surface of 

 lime-water. Carbonic acid gas is found accu- 

 mulated in many caverns of volcanic. districts, 

 and particularly in the grotto del cani at Pau- 

 bilippo, near Puzzuoli ; being disengaged in 

 such circumstances by the action of subterra- 

 nean fire, and, possibly, of certain acids, upon 

 the limestone strata. It often issues from 

 fountains in copious currents, as at Franzens- 

 brunn, near Eger, in Polterbrunnen ; near Trier ; 

 and Byrreshorn. This acid gas occurs also 

 frequently in mines and wells, being called 

 choke damp, from its suffocating quality. Its 

 presence may, at all times, be detected, by 

 letting down a lighted candle, suspended from 

 a string, into the places suspected of contain- 

 ing this mephitic air. It exists, in consider- 

 able quantities, in the water of every pump- 

 well, and gives it a fresh and pleasant taste. 

 Water, exposed some time to the air, loses 

 these aerial particles, and becomes vapid. 

 Many springs are highly impregnated with 

 carbonic acid gas, and form a sparkling beve- 

 rage ; such as the Seltcrstvasser, from Sellers, 

 upon the Lahn, in the grand duchy of Nassau ; 

 of which no less than two millions and a half 

 of bottles are sold every year. The amount 

 in Saratoga water is very great. A prodigious 

 quantity of a similar water is also artificially 

 prepared under the name of aerated or soda 

 water. * 



Carbonic acid occurs in nature, combined 

 with many salifiable bases ; as in the carbo- 

 nates of soda, baryta, strontia, magnesia; the 

 oxides of iron, manganese, zinc, copper, lead, 

 &c. From these substances it may be sepa- 

 rated, generally speaking, by strong ignition, 

 or more readily, by the superior affinity of mu- 

 riatic, sulphuric, or nitric acid, for the earth 

 or metallic oxyde. It is formed whenever ve- 

 getable or animal substances are burned with 

 free access of air, from the union of their car- 

 bonaceous principle with atmospheric oxygen. 

 It is also formed in all cases of the spontane- 

 ous decomposition of organic substances, par- 

 ticularly in the process of fermentation ; and 

 constitutes the pungent, nqxious, heavy gas 

 thrown off, in vast volumes, from beer vats. 

 See DISTILLATIOX and FKHMKNTATIOX. Car- 

 bonic acid is also generated in the breathing 

 of animals ; from 4 to 5 per cent., in volume, 

 of the inhaled oxygen being converted, at each 

 expiration, into this gas, which contaminates 

 the air of crowded apartments, and renders 

 ventilation essential to health, and even to life; 

 witness the horrible catastrophe of the Black- 

 hole at Calcutta. 



Carbonic acid gas is destitute of colour, has 

 a sourish, suffocating smell, an acidulous pun- 

 gent taste, imparts to moist, but not dry, litmus 

 paper, a transient reddish tint, and weighs per 

 100 cubic inches, 46 grains ; and per cubic 

 foot, 803J grains ; a little more than 3 oz., 

 avoirdupois. A cubic foot of air weighs 

 about two-thirds of that quantity, or 527 grains. 

 It may be condensed into the liquid state by a 

 Pressure of 40 atmospheres, and this liquid 

 9iay be then solidified by its own sudden 

 spontaneous evaporation. If the air contain 

 more than 15 per cent, in bulk of this gas, it 

 becomes unfiufor respiration and combustion, 

 264 



animal life and candles being speedily extin- 

 guished by it. 



Before a person ventures into a deep well, 

 or vault containing fermenting materials, he 

 should introduce a lighted candle into the" 

 space, and observe how it burns. Carbonic 

 acid being so much denser than common air, 

 may be drawn out of cellars or fermenting 

 tubs, by a pump furnished with a leather hose, 

 which reaches to the bottom. Quicklime, 

 mixed with water, may be used also to purify 

 the air of a sunk apartment, by its affinity for, 

 or power of, absorbing this aerial acid, (lire's 

 Diet, of drts, fyc.) 



CARBURETTED HYDROGEN. A com- 

 pound of carbon and hydrogen gases, of which 

 there are several species ; such as oil gas, coal 

 gas, defiant gas, oil of lemons, otto of roses, oil or 

 spirits of turpentine, petroleum, naphtha, naphtha- 

 line, oil of tvine, caoutchoudne, and caoutchouc or 

 Indian rubber, (lire's Diet, of Arts, $T.) 



CARDINAL, SCARLET (Lobelia cardinalis). 

 An herbaceous hardy plant, a native of Virgi- 

 nia. It blows its scarlet flowers in July, and 

 again in October. It loves bog earth and 

 shade, and the root should be parted every 

 spring. Ripen the flower intended for seed 

 under a glass hung over it, for it rarely ripens 

 in this climate without assistance. This 

 superb wild flower is worth a place in every 

 garden. It continues blooming a long time. 

 Five or six species are known in the United 

 States. 



CARDOON, or CHARDON (Span, cardo, 

 an artichoke ; Lat. Cynara cardunculus}. A 

 kind of wild artichoke, which is principally 

 confined to garden culture, as it has not yet 

 been employed as an article of food for any 

 sort of live stock. 



The stalks of the inner leaves, when ren- 

 dered tender by blanching, are used in stews, 

 soups, and salads. A light rich soil is most 

 suitable to this vegetable, dug deep and well 

 pulverized. The situation must be open, and 

 free from trees, for, like the artichoke, it is im- 

 patient of confinement. It is propagated by 

 seed, which may be sown at the close of 

 March ; but, for the main crop, not until the 

 early part of April ; those plants raised from, 

 earlier sowings being apt to run at the close 

 of autumn : for a late crop, a sowing may be 

 performed in June. The best practice is to 

 sow in patches of three or four rows, four feet 

 apart each way, to be thinned finally to one in 

 each place, the weakest being removed. The 

 seedlings are nearly a month in appearing. 

 If, however, they are raised in a seed-bed, they 

 will be ready for transplanting in about eight 

 or ten weeks from the time of sowing, and 

 must be set at similar distances as are speci- 

 fied above. The plants of the first sowing are 

 generally three weeks before they make their 

 appearance ; those from the later ones, about 

 two. If, after a lapse of these times, they do 

 not appear, it should be ascertained if the seed 

 is decayed, and in that case the sowing may 

 be renewed. The seed must be sown rather 

 thin, and (Jovered with about half an inch 

 depth of mould. When about a month old, 

 the seedlings, if too crowded, must be thinned 

 to four inches apart ; and those removed may 



