Page:The American Cyclopædia (1879) Volume XII.djvu/490

 476 NOMENCLATURE ber of equivalents of the latter are usually acids ; those containing but few equivalents of oxygen, are bases ; while not unfrequently the intermediate degrees of oxidation are indif- ferent bodies. Thus, of the oxides of manga- nese just referred to, the proto- and sesqui- oxides are bases, and the bin- (or per-) oxide is an indifferent body ; there are also two com- pounds containing more oxygen which are acids, viz. : Manganic acid, containing Permanganic acid, " 1 eq. of manganese, 3 eqs. of oxygen. 2 eqs. of manganese, 7 eqs. of oxygen. The compounds which oxygen forms with the metals are, however, for the most part bases, those with the metalloids acids. Many of the binary compounds of sulphur are analogous to those of oxygen. They are termed sulphides, and as a rule correspond with the oxides. Like the latter, they may be classed as acids, bases, and indifferent bodies. Members of the first two classes, like the oxyacids and bases, unite with each other to form sulpho-salts. They have, however, comparatively little affini- ty for the other elements, or for compounds not containing sulphur. The sulphur bases and the indifferent sulphides are distinguished by the same prefixes as the oxides. Thus, the three sulphides of iron are termed respective- ly : protosulphide of iron, symbol FeS ; sesqui- sulphide of iron, Fe 2 S 3 ; and persulphide of iron, FeS 2. The sulphur acids are named by prefix- ing the term sulpha to the name of the corre- sponding oxygen acid ; thus, the compound of carbon and sulphur analogous to carbonic acid is called sulpho-carbonic acid. The binary compounds of chlorine and of several other elements are named in a similar manner. Thus, with the other elements, oxygen forms oxides ; sulphur, sulphides (sulphurets) ; chlorine, chlo- rides; bromine, bromides; iodine, iodides; fluorine, fluorides ; phosphorus, phosphides (phosphurets) ; carbon, carbides (carburets) ; nitrogen, nitrides, &c. When several chlo- rides, bromides, iodides, or fluorides of any one metal occur, they are distinguished by the same prefixes as the oxides. The binary com- pounds of these elements are, however, usually regarded, not as acids and bases, but, like the ternary oxygen compounds, as salts. This ex- ception is one of the fruits of the too hasty as- sumption by the founders of the nomenclature, that oxygen was the universal acidifying prin- ciple ; an error which lies at the basis of their system, and constitutes one of its greatest faults. It has since been ascertained that the metalloids in question, as well as some others, by uniting with hydrogen, form acids as ener- getic and as well characterized in every respect as the oxy-acids ; for example, chloride of hy- drogen, fluoride of hydrogen, &c. These are called hydracids. Instead of being written out in full, as they have just been given, the names of these compounds are formed by fusing to- gether those of their constituents, as chlorhy- dric acid, fluorhydric acid, &c. The synony- mous names, as hydrochloric and hdyrofluoric acids, are still often used, but are not in ac- cordance with the general principle that the name of a compound must commence with that of its electro-negative component; their inaccuracy was pointed out simultaneously by Thenard and Dr. Hare of Philadelphia. The hydracids are capable of uniting directly with basic oxides or with metals, with separation of hydrogen in either case; in the first in- stance the hydrogen unites with the oxygen of the metallic oxide to form water, in the latter it is evolved as gas. The compounds thus formed were at first thought to contain oxygen, the hydracids being supposed to be oxygenated, and were admitted as salts without question ; indeed, one of them, common sea salt, is that from which the very idea of a salt was originally derived. An attempt has since been made to refer them to the oxygen class by supposing that they constitute when in so- lution, not simple binaries, but compounds of the original undivided hydracid with an oxide. Thus the compound of chlorine and sodium (common salt) was at one time often called chlorhydrate (or hydrochlorate) of soda; it being claimed that the elements of an equiva- lent of water had united with its constituents to form chlorhydric acid and oxide of sodium (soda). From this (conventionally admitted) property of chlorine, and the metalloids allied to it, to form salts by direct combination with metals, they have been termed halogens (salt producers; Gr. aAf, [sea] salt, and yevvaeiv), and their salts have been called haloid (from a/If and eldoc, in the likeness of) to distinguish them from the oxygen salts. The names of ternary compounds or salts, in the original ac- ceptation of the term, are formed by combining the names of the acid and base of which they are composed, the name of the acid or electro- negative component supplying the generic, the base or electro-positive compound the specific name. If the name of the acid terminates in ic, this termination is changed into ate ; if in ous, into ite ; and to the words thus formed the name of the base is added. For example, sulphuric acid and oxide of lead form sulphate of the oxide of lead ; sulphurous acid forms a sulphite of the same oxide ; while hyposulphu- rous acid produces a hyposulphite, and hypo- sulphuric acid a hyposulphate. In like manner the compounds of nitric acid are nitrates, and those of nitrous acid nitrites of the bases with which they may be combined. When a salt contains as its base the oxide of a metal which forms but one well defined base with oxygen, its name is usually shortened by leaving out the words " of the oxide," which are always under- stood. Thus, it is customary to say sulphate of lead, instead of sulphate of the oxide of lead ; nitrate of potassa, instead of nitrate of the oxide of potassium. In case more than one basic oxide of the same element is capable of