CHEMICAL NOMENCLATURE. 



CHEMICAL NOMENCLATURE. 



7M 



or, by dissolving olefiuit gM in sulphuric acid, nod decomposing the 

 compound with water 



e.ii, + ino BO, + IHO = C.H.IHO + JHO so,. 



Certain bodies, which differ widely from one another in their physical 

 properties, may be composed of the same element* in the name proportion. 

 Thus, all the oletines, ethylene, pr-ipyU-ne. l.\itylene, *c., consUt of 

 8571 per cent, of carbon and 14-29 per cent, of hydrogen. These bodiee 

 lifter physically a< to their densities, as liquids and gases, and as to 

 the temperature at which they pass from the one state into the other. 

 They all combine directly with bromine, and give rise thereby to pro- 

 ducts having complete chemical analogy with one another. The body 

 thus formed by the union of ethylene with bromine contains for every 

 two atoms of bromine four of carbon and four of hydrogen. The cor- 

 responding product from propylene contains six of carbon and six of 

 hydrogen lor every two of bromine ; that from butylene contains eight 

 of carbon and hydrogen for two of bromine, 4c. Whence the formula 

 of the bodies are respectively 



C 4 II,Br,, C.TI.Br, C.H.Br, Ac. 



and, consequently, the formula; of the olefines themselves are 



Kthylone 

 l*ropTlen 

 ButTlene 

 Amylene 



C.H, 

 C,H. 



C..H, 



Moreover, it is found that the specific gravities of these defines, in the 

 state of gas or vapour, at the same pressure and temperature, are 

 respectively 



KthTltne 

 Propylene 

 Butyltne 

 Amylrne 



9784 

 1-467 



i !-<; 



2-68 



numbers nearly in the proportion of 4, 6, 8, 10, respectively, showing 

 that in the same volume of the different vapours, the atoms of the two 

 elements are present in numbers proportional to the above. It is thus 

 that the specific gravity of a substance in the gaseous state, that is, 

 ito vapour density, shows how many atoms (relatively) ; t contains, 

 and gives thus so far evidence of it* rational formula. For the relation 

 between the rational formula of a body and its specific gravity, when 

 in the solid or liquid state, the reader is referred to ATOXIC VOLUME. 



< HKMICAL NOMENCLATURE. The experiments of the early 

 chemist* xoon increased the number of distinct substances to such nn 

 extent, as to render at least a crude nomenclature indispensable, in 

 order to define new bodies in such a manner as to enable subsequent 

 experimenters to recognise them and to apprehend something of their 

 nature. Thus, to indicate the analogies which existed between different 

 sulphates, they designated them by the name of ri trial* ; for a similar 

 reason they gave the names horn tilver, horn lead, &c., and butter oj 

 antimony, butler of bitmttth, butter of zinc, to compounds of chlorine 

 with certain metals : these names indicating the resemblance in appear- 

 ance which the first bore to bom and the second to butter. 



The names of the simple elements have been formed on no definite 

 plan ; they have been given according to the choice of their first dis- 

 coverer, or of the chemist who first described their properties. Many 

 of them, as antimony, strontium, barium, potassium, aluminium, have 

 received their names from substances in which they existed as charac- 

 teristic constituents, and which were so named before any certain 

 knowledge of their composition existed. On the introduction of the 

 present system of nomenclature, an attempt was made to give to the 

 laments names characteristic of their properties. This idea it was 

 found impossible to carry out systematically ; some of the commonest 

 names had been so engrafted in the science that it was found impos- 

 sible to root them out. Whole classes of the elements, too, have so 

 little that is characteristic, that it would be difficult to find adequately 

 descriptive names. Further, in framing a systematic nomenclature, it 

 is impossible to avoid giving it the impress of the theoretical ideas 

 prevailing at the time. These names become subsequently modified, 

 from the progress of the science and the discovery of new bodies. 

 Hence, a nomenclature, quite rational at its birth, ceases, after some 

 time, to be in harmony with the state of the science. Many of the 

 names given to the elements at the time of the foundation of our 

 present nomenclature, were in accordance with the theoretical views 

 prevailing at the time, and have been found by the further progress of 

 the science to be inappropriate. Thus oxygen, discovered about that 

 time, was named from ofwt, acid, and ytn>ttt, to generate, because it 

 was conceived to be the acidifying principle ; the subsequent recog- 

 nition of the non-existence of oxygen in bodies endowed with highly 

 acid properties, and the existence of oxygen in strictly basic com- 

 Ilium!*, showed the inappropriateness of the name. For the names of 

 the elements, see CHKMICAL FORMULA. 



Simple bodies are divided into mrtallniil* and metalt. This classifi- 

 cation was based, at first, principally on physical characteristics; but 

 the best distinction is that founded on their chemical properties, 

 namely, that metalloids, in uniting with oxygen, generally form acid 

 compound*, whilst metals, in combining with oxygen, generally give 

 rue to base*. 



Every binary compound, or compound of two elements, which can 

 be rendered liquid and a conductor of the electric current, is decom- 

 posed by the action of a sufficiently powerful battery; one of its 

 elements is attracted to the positive pole, and the other to the negative 

 |KI|.\ As opposite electricities attract each other, the rf-fro->< 

 body, or acid element, is that which goes to the positive pole; and the 

 rlrctro-iHiritire body, or basic element, is that which goes to the negative 

 ]M>le. The metalloids are consequently, as a general rule, electro- 

 negative bodies, and the metals electro-positive bodies. 



T.i name a binary compound, we enunciate first the name of the 

 electro-negative body, giving to it the termination ide or ur 

 follow it by the genitive case of the name of the electro-positive body : 

 thus, oxide of silver, stilphuret of mercury. 



Of binary compounds, by far the most important are those which 

 the elements form with oxygen. They afford the best examples of the 

 principles on which nomenclature is applied. From their properties 

 they may be divided into acids and bases. 



Nomenclature of acid*. The name*; of acids are obtained by affixing 

 to the names of the elements, or some abbreviation of those names,' 

 the termination ic. Thus the combinations of sulphur and of titanium 

 with oxygen are respectively sulphuric and titanic acids. \\ I 

 element combines in more proportions than one with oxygen t<> form 

 an acid, the termination ota is applied to tluit which contains least 

 oxygen : thus we have tidphurov* arid and mlphnrie acitl. At the 

 time when these rules were established, it was thought that a body 

 could not form with oxygen more than two acid compounds ; but mili- 

 sequently cases were discovered in which the body formed four or live 

 coinl, inations with oxygen. These cases were provided for by tl 

 of the Greek prefixes v*o (under) and inrtp (above). Thus an 

 containing less oxygen than sulphurous acid was called hyposul/iiiiiniiM 

 iii-i:/, and an acid between sulphurous and sulphuric acid was called 

 hypotul/thtiric arid. In the series of acids which chlorine forms with 

 oxygen, we have hypochlorom afid (CIO), cMurota acid (CIO,), /.//,,.- 

 Merit acid (CIO,), and chloric acid (CIO,) ; on the discovery of an 

 acid (CIO,) containing more oxygen than chloric acid, it was termed 

 hi/perchloric, or briefly, perchloric acid. There are, similarly, y 

 and permanganic acid*. A class of bodies exists which have acid pro- 

 perties, but in which sulphur is contained in the place of oxygen ; 

 thus, AsS ? , AsS,, CS V which are termed respectively, 

 fiitji/iarsrnioiu, and iitiphocarbonic acid*. Certain elements, as chlorine. 

 sulphur, iodine, form acid compounds with hydrogen. These are 

 respectively termed hydrochloric, hydrofitlphuric, and hydrlodie aciih. 



Nomenclature of BOM*. The compounds of metals with oxygen are 

 generally bases. In accordance with the principle of nomenclature 

 before stated, they are termed oxides. In certain cases, metals combine 

 with several proportions of oxygen ; these combinations are always in 

 simple ratios, and according to the law of multiple proportions. To 

 the one containing an atom of oxygen for an atom of nut.il, tin- .TTU 

 protoxide (wpum,Jirtt), or simply oxide is applied; and to the otlirr*. 

 the terms tetquioxide, binoxide, teroxide, according as they contain 

 11, 2, or 3 times as much oxygen as is contained in the protoxide. 

 Thus we have MnO, protoxide ; Mn,0,, seequioxide ; and MnO,, bin- 

 oxide of manganese. A similar nomenclature obtains with higher 

 oxides, but these have generally acid properties. For instance, man- 

 ganese combines with three atoms of oxygen to form a compound 

 (MnO,) which is termed manganic acid. It also combines, in the pro- 

 portion of 2 equivalents of manganese to 7 of oxygen, to form an acid 

 which is termed permanganic acid. The term peroxide is frequently 

 applied to that oxygen compound which contains most oxygen, if it be 

 not an acid ; thus we say indifferently sesquioxide and psradds i if in >u. 



Certain oxides exist containing less oxygen than the protoxides. These 

 are termed mboxide* : as Cu,O, suboxide of copper ; Pb,0, luboxide of 

 lead. They are generally not very stable compounds. 



The combinations of the other elements are similarly named. The 

 combinations of sulphur, phosphorus, chlorine, carbon, and nitrogen 

 with other elements are termed respectively sulphides, phosphides, 

 chlorides, carbides, and nitrides. The termination uret is becoming 

 gradually replaced by ide. 



Where several combinations of the same clement* exist, the same 

 rules are applied as in the case of the oxides. Thu, | Tot ..chloride of 

 iron, Fed, and sesquichloride of iron, Fe.Cl, ; protochloridc of tin, 

 SnCl, and bichloride of tin, SnCl, ; terchloride of antimony, SnCl,, and 

 pentachloride of antimony, SbCl,. 



In the series of combinations which sulphur forms with phosphorus, 

 we have the hemisulphide, I'.S; inonosulphide, 1'S ; tersulphide, P8, ; 

 pentaHulphide, P8, ; and dodecosulphide, 1'S,,. We have also iodide 

 of cop|ier, Cul ; and siibiodide of copper, Cu,I. 



A'ltmenrlature of Kail*. Acids in combining with bases give rise to 

 ternary compounds which are called salts. To form their names those 

 of the acid and base are combined, so that the name of the first deter- 

 mines the kind, and of the latter the species ; the termination ic and 

 nut of the acid being respectively changed into ate and ite. Thus, we 

 should say lulphatr ./ ^n>tiu-idt of iron, tu/pliite of protoxide of iron, 

 hypoiul/i/iiiii i if protoxide of iron, to express the combinations of sul- 

 phurous, sulphuric, and hypnsulphuric acid, respectively, with oxide of 

 iron ; or the existence of oxygen in the base being supposed, we may 

 say lalphate of iron, tulphite of iron, hypotuJphate of iron. 



In cases in which an acid for example, sulphuric acid combines 



