ORGANIC COMPOUNDS. It was formerly believed that the compounds to which the term organic is applied could only be produced by a vital force acting in a more or less complex animal or vegez!tble organism. It is, however, now known that this view is altogether untenable, and that ninny substances which are products of animal or vege table organisms may also be farmed artificially in the laboratory. Thus urea, the chief amid most characteristic organic constituent of urine, may be formed by the direct union of chlorine and carbonic acid (which form phoxgene gas) with ammonia; and glycose or grape-sugar may he artificially produced from starch, woody fiber, paper, lumen, etc. Although such cases as that of urea, in which a complex organic product is produced by the direct union of three inorganic substances (and many other cases of the same nature might he adduced), show that there is no definite line of. demarkation between organic and inorganic products, it is useful, as a matter of convenience, to classify chemical comiipounds according to their natural origin.
The following are the leading characteristics of organic compounds: Those which occur naturally rarely consist of more than four elements—viz., carbon, hydrogen, miitro gen, and oxygen—although a few contain sulphur, and possibly (but this is doubtful) phosphorus. By artificial means, however, organic compounds can be formed contain taiuing chlorine, bromine, iodine, selenium, tellurium, and many of the metals. Carbon is universally present both in natural and artificial organic compounds. The number of equivalents entering into the composition of organic compounds is usually higher than in the case of inorganic compounds. There is no organic compound into which less than two equivalents of carbon enter, and, according to some chemists, both oxygen and sul phur only enter these compounds in double equivalents- -llelissic acid, for example, one of the constituents of wax), is represented by C66II66O4; that is to say, each equivalent of time acid is composed of 124 equivalents of the elements entering into its composition= and each equivalent of the solid fat, commonly known as stenrine. contains 114 equiva
lents of carbon, 113 of hydrogen, and lw of oxygen. No instance is known in which an organic compound has been formed by the direct union of its elements in a free state, as many sulphides, chlorides, and oxjdes (for example) are formed in inorganic chemistry. Their extreme readiness to decompose under the influence of heat, fermentation, putre faction, etc., is another claracteristic s f organic compounds, although some artificially prepared inor ,mic compounds—us, for example, chloride of nitrogen—are also very unstable.
The following scheme may serve to elucidate the arrangement of the elements in organic compounds. Such compounds may be composed of carbon and oxygen, as car bonic oxide, or of carbon and hydrogen, as oil of turpentine, C:6H,6; or of car Mn and nitrogen, as cyanogen, C,N; or of carbon, hydrogen, and oxygen, as grape sugar, C„II„0,,; or of carbon, nitrogen, and oxygen, as anhydrous cyanic acid, C,`O; or of carbon, hydrogen, and nitrogen, as nicotine, or of carbon, hydrogen, and sulphur, as oil of garlic, or of carbon, hydrogen, nitrogen, and oxygen, ms caf femme, ('jmIIroN,O,: or of carbon, Kydrogen, nitrogen, and sulphur, as oil of mustard, or tinally, of carhop, hydrogen, nitrogen, oxygen, and sulphur, as taurine, Ilence organic compounds msy be binary, ternary, quaternary, or quinary in thoii composition.