Page:The American Cyclopædia (1879) Volume III.djvu/785

CARBONIC OXIDE CAKBURETTED HYDROGEN 775 lump of the gas was kept for a minute in a red- hot crucible, and a pound of mercury was im- mediately afterward frozen with it. The vapor given off from the solid gas possesses a higher tension than that from any other substance; and, unlike the vapor from other bodies, it is developed by lowering instead of raising the temperature. -According to modern notation, carbonic acid gas is more properly to be called carbonic anhydride, or carbon dioxide. No definite hydrated carbonic acid is known, the anhydride, both in the form of gas and in its denser conditions of liquid and solid, being, as its name indicates, free from water; but it ap- pears convertible into a true acid by solution in water, COa + HjO, yielding HjCOs; this in turn combines with bases to form the well known series of salts called carbonates. (See CARBONATES.) CARBONIC OXIDE, or Carbon Monoxide, a gas containing one equivalent less of oxygen than carbon dioxide, being a combination of one equivalent each of carbon and oxygen hence represented by the symbol CO. It contains 42'86 per cent, of carbon and 57'14 per cent. of oxygen. Its weight compared with air is 0'9G7. It is a product of imperfect combus- tion, and is generated in large fires in close furnaces in enormous quantities, mixed with carbonic acid gas and other gaseous products of combustion. By the introduction of atmos- pheric air to it while highly heated, it com- bines with another atom of oxygen, burning with a blue flame and becoming carbon dioxide. It is visible by night undergoing this change, as it meets the air when issuing from the tops of chimneys of large furnaces, indicating im- perfect combustion within the furnace. In large iron establishments this gas is utilized by causing it to burn with the fresh air admitted under the boilers of the steam engines, or in the chambers constructed for heating the air blown into the furnaces. If the flow of the gases be obstructed, or in any way irregular, explosions may result by sudden admission of oxygen or of atmospheric air to them when highly heated. When mixed with pure oxygen, carbonic oxide is by the electric spark con- verted into carbon dioxide with an explosion. The oxide may be reobtained by passing the dioxide through tubes containing red-hot charcoal or metallic iron, which take up one atom of oxygen. Carbonic oxide is a colorless gas, without smell or taste, but more irrespira- ble and poisonous than carbon dioxide. Its in- halation as it issues from furnaces sometimes causes immediate asphyxia to the workmen. It undergoes no change, like carbonic acid gas under heavy pressures at the lowest tempera- tures ; nor is it taken up by water like this gas, nor does it produce similar acid reactions in changing vegetable blues to red. Heat and electricity produce no change in it when alone ; when mixed with carbonic acid gas, it may be separated and obtained pure by introducing quicklime or potash, which absorbs the higher oxide. Carbonic oxide may be obtained with facility by heating oxalic acid with five or six times its weight of oil of vitriol, and absorbing the carbonic acid gas by quicklime, as stated above. Cuprous chloride gradually absorbs carbonic oxide if agitated with it. CARBUNCLE, an unhealthy inflammation of the surface, accompanied by a sloughing of a circumscribed portion of the subcutaneous cel- lular tissue ; of the same nature as a boil, only deeper seated and of larger size. It begins by a hard, tense swelling, of a livid and shining appearance, and with severe burning pain; it is generally accompanied by feverish symptoms, often of considerable severity, and is slow in its progress ; in from one to three weeks the skin becomes thin and perforated by numerous openings, from which issues a thin whitish dis- charge ; the ulcers finally unite into one of large size, at the bottom of which is seen a soft grayish mass, the slough of the cellular tissue, with a very disagreeable odor ; this slough or core is soon separated, leaving a deep excavation, with thin edges, and sur- rounded by a livid skin. The swelling may vary in size from one to six inches in diameter, and is usually found upon the back, nape of the neck, and nates ; it may occur also on the shoulders, chest, lower jaw, and lower extrem- ities. It is most common in adults and old persons whose constitutions have been broken down by intemperance, exposure, hard study, or mental anxiety ; it is always an evidence of a vitiated state of the blood and of derange- ment of the digestive organs. If of large size, in an enfeebled constitution, or on or near the head, a carbuncle may endanger life. The lo- cal treatment which has been found the best is to make free incisions into the tumor, to al- low the escape of the discharge and sloughs, to relieve the engorged tissues by the loss of blood, and to excite them to healthy suppura- tion and granulation; warm and stimulating poultices, ointments, and lotions hasten the cure. At the same time the diseased secretions of the alimentary canal should be removed by purgatives; the strength supported by nourish- ing diet, bark, and the mineral acids ; irritabil- ity calmed by small doses of opium ; and the blood renovated by a judicious exhibition of preparations of iron. CARBUNCLE, in mineralogy, the name of a precious stone much valued by the ancients, said by some to be the ruby, while others regard it as the garnet. The Latin name carbunculw, like the term ruby, seems to have been applied to very different minerals, and may have compre- hended the red sapphire, or oriental ruby, the spinelle ruby, the red topaz, and the red garnet. CARBURETS, or Carbides, combinations of carbon with the other elements. Cast iron, being a mixture of carbon with iron, is called carburet of iron. For carburet of sulphur see CABBON DISULPHIDE. CARBURETTED HYDROGEN, the name of two compounds of carbon and hydrogen, one dis-