MADAN ON SOME POINTS IN THE VI.-Remarks on some Points in the Nomenclature of Salts. By H. G. MADAN F.C.S. (Read December 2nd 1869.) IT is very much to be regretted that the subject of chemical nomenclature is in such an ynsettled state. It seems a real reproach to chemists that scarcely two text-books can be found in which the same system of names is adopted and that there is hardly a single number of a scientific periodical which does not contain specimens of totally different systems. The extreme difficulty of teaching the science under such conditions is pal- pable and it is a poor apology to say that text-books iii other branches of science and even classical text-books (e.g. the Public Schools’ Primer as compared with +,he Eton Grammar) vary greatly in their terminology.But while our ablest chemists appear to agree to differ in their views on the subject it is hard to suggest what should be done. The following remarks are offered with great diffidence ; they may have at most the value of calling more attention to the subjcct. The ftict observed by chemists is that certain radicles (L6 elec-tronegative radicles ”) of whi’ch chlorine is an example unite in one or more than one definite proportion with certain other radicles (“ electropositive radicles ”) of which mercury is an example to form distinct series of compounds or salts. NOMENCLATURE OF SALTS. The problem is-In the first place to provide a general name for each group of salts which is characterised by contairiing the same electro-negative or electropositive radicle.In the next place to provide special names which may serve to distinguish the several members of each of the above groups and to mark the position which each member holds in the seriea to which it belongs. The first part of the problem has been solved by general consent (so far as regards the electronegative radicles) as fol- lows :-The termination of the received name of the electronegative radicle is altered into -ide -ite OF -ate ; the two latter terrnina- tions denoting that oxygen is considered to be present in the radicle. Thus salts containing the chlorine radicle are all called chlorides ; salts containing a radicle in which chlorine is asso-ciated with a certain amount of oxygen are called chlorites or chlorates according to the amount of oxygen they contain.* It appears unlikely that these terminations will at present be changed.The second part of the problem has been solved in two ways at least. 1. By adding a prefix such as proto-(or mono-) di- th-,per- &c. to the existing generic name for the salts of the electro- negative radicle ; with it is associated the name of the electro- positive radicle unchanged in form and used either in the yos-sessive case or adjectivally. Thus we have ‘‘protochloride of mercury” (or mercury proto- cliloride) and ‘‘ dichloride of mercury ” (or mercury dichloride or perchloride) as the respective names for the two combina- tions which mercury forms with chlorine. 2. By changing the termination of the name of the electro- positive radicle into ic or ous the generic name for the salts of the electroiiegstive radicle being left unaltered.* Some few substances such as chlorine and sulphur are found to form in a-sociation aitb oxygen mvre than two radicles. Probably tlie3e cases might be best met by making an alteration in the vowel immediately preceding the -te as proposed long azo tv hlr. Griffin. Thus the “perclilorate ” radicle might be called ’g chlorote.” The piinciple of indicating the amount of oxygen in the radicle by B shange of a vowel in the name has been already accepted there seems no reason why we should not extend it. MADAN ON SOME POINTS IN THE Thua we have the names ‘‘mercurous chloride ” and “ mer-curic chloride ” for the two mercury aalts alluded to above.The first system of nomenclature would seem preferable to the second since- a. It requires the minimum of change in existing name8. The salts in which chlorine is the electro-negative radicle are all termed chloridcs ; those in which mercury is the electro- positive radicle are all termed mercury salts. When we wish to denote certain classes of chlorides we merely add a prefix instead of interfering with the termination of a word. b. It is the more elastic system of the two. It can be adapted to any series of aalts however extensive while the ic and ous system is applicable only tu a aeriee consisting of two members. The latter is quite inadequate for instance to express the series of nitrogen oxides in such a way as to show their stoichiometrical relations.” It is quite true that it ia at present rare to find a radicle forming more than two well defined series of salts (except oxides) but what we want is a system which will adapt itself to future discoveries without giT-ing us the trouble of re-con-structing it ; for the preseirt it would be very coiivenierit to retain the old prefixes proto-and per-; the7 are to say the least open to no greater objections than -ous and -ic.f Both indicate merely relative position ;both are applicable to series consisting of only two members.But in using proto- and per- we approach most nearly to the usual nomenclature for series consisting of rrrany members such as the oxides (protoxide8 dioxides trioxides &c.).There is moreover an occasional advantage in being able to speak of a group of substances as “protosalts,” in poiiiting out analogies between them. I do not know that it has been proposed to talk of “ic salts ” and “ om salts.” I have some difficulty ir_ seeing the advantage of another practice which is becorning commoii viz. that of calling certain * I am quite aware Ohat there is a very great difference in properties bebaeen oxides ; between for instance the substance represented by the formula N,O and that represented by the formula N,O,<. But I cannot help thinking that if we mnst choose an alternative it is preterable thab the name should express place in a series rctther than difference in chemical properties.Monatomic mercury and diatomic mercury S~IOW in combination. an equally remarkable coiitiazt of properties ;but we do not assign them totally distinct uames ; at the most we change the termination of the name. t Perbaps meio- as haviug a purely relative meauing wonld be preferable to proto ef. (‘meiocenc.” KOMEKCLATURE OF SALTS. 25 radicles by their Latin names. Why for instance should we speak of ‘‘ argentic nitrate,” when we obtain (besides oxygen and nitrogen) siluer and only silver from the substance. We cause hydrogen chloride to act upon excess of iron and we obtain a salt which it is proposed to call ferrous chloride. It might be convenient to distinguish the atom from the molecule by some such distinct name but if so the system should be carried out fully and consistently or not at all.We must have kalic natric stibic hydrargic &c. At present no such consistency is observed and until we are sufficiently educated to talk of a ferrum saucepan a cuprum tea-kettle and an argeiitum spoon it would seem preferable to adhere to names in common use. The more sparingly we alter ordinary names against which there is no serious objec- tion the more acceptable and intelligible will be our nomen- clature. I cannot help thinking that the system of terminology origin- ally proposed I believe by Mr. Harcourt which is adopted by Professor Roscoe in his ‘‘ Lessons in Elementary Chemistry,” and by Mr. Watts in the new editiofi of ‘‘ Fownes’ Chemistry,” has more of the elements of simplicity permanency yet elasti- city than any other.It differs in a comparatively slight degree from the older nomenclature and hence old chemists have little difficulty in understanding it. It is so far as one can see readily adaptable to the progress of chemical discovery and hence young students may learn it without much risk of having to un- learn it. It is difficult to see why we should occup-j ourselves in criti- cising the euphony of adjectival tevminations (e.g. nickelic ironous) when our language undoubtedly permits US to dispense with them. No one would speak of a golden watch a carl->onic filter or a mercusic barometer. It may not be too much to hope that the terminations -ic and -ous may disappear altogether from our nomenclature if the purpose they serve can be fulfilled as well or better in other ways.From the unwieldy names which we are now manufacturing for chemical substances it would seem possible to endeavour to express too much in a name. What is mainly required ap- pears to be that the name should be a rational and sufficiently distinct mark for the sulnstance to which it is applied. MADAN ON SOME POINTS IN THE Professor Attfield thought the chief point about a name should be that it was unalterable. Re objected to the use of vowels or of Latin or Greek numerals to express the name of a salt as our views of the constitution of a substance sometimes change and when such is the case it becomes necessary to alter the name. The President said that Mr.Madan’s proposal to revert to the use of such terms as proto- sesqui- and per- in order to designate the place of bodies which differ in their quantity of oxygen and chlorine in a series implies that the series is known whereas we are constantly altering our knowledge of such series. These words have been productive of considerable in- convenience and confusion and he thought the terminations -ous and -ic as used by most writers including Dr. Roscoe and Mr. Watts were far more convenient. These terminations only denote a kind of difference in the constitution of certain substances such a difference may be ascertained as a matter of fact. We may find other terms of each series and a body which was first may become second but if it contains less oxygen than another it is correctly distinguished by the ter- mination -ous instead of 4.Mr. Madan seems to thiiik it necessary always to retain Latin words if they are used in certain cases. It is held by some persons that a variety of name is in many cases desirable amongst such compounds as Prussian blue where iron figures in two capacities. He the President was not aware that those who advocate the view against which Mr. Madan contends have ever asserted that a Latin name if used at all ought universally to be employed; and if English names are insisted on we should be led into eccentricities not less remarkable than those against which the author contends. Carbon and sulphur are Latin words which if discarded in favour of the English words would lead to words like char- coalic oxide and charcoalic acid and brimstonic acid and brim- stonous acid a change which did not appear to him avery great improvement.It is exceedingly desirable that everybody should bring forward his own impression in the matter because it is only by general consent that any important system can be established. Mr. Vernon Harcourt thought the difficulty attaching to the choice of names was inevitable in the present state of chemistry. Either a name must be unsystematic and merely NOMENCLATURE OF SALTS. express one or two facts about the particular substance e.g. corrosive sublimate; or if it be systematic and expresses a relation between the particular substance and others it must embody a theory not yet definitely established.With reference to English and Latin names sulphur has for so long a time been used as an English word that it is in reality no less so than brimstone. The latter he supposed was a German word and sulphur was originally Latin but it has now become as thoroughly English as my word in the language. With regard to using ic and ous he thought that the terminations pqoto and per might equally be said to express facts; and it appeared to him that the objection raised by Mr. Madaii that the termina- tions ic and ous served only for two terms of a series and that this mode of expression cannot be extended in cases where the series extends beyond two terms was a just one. At the same time he thought that where there are two parallel series of salts (such as mercurous and mercuric salts ferrous and ferric salts) it is a great convenience to have these terms and ‘‘ ferrous salts ” is perhaps a better expression than ‘‘ iron proto-salts,” which Mr.Ma dan recommends as a substitute. Mr. McLeod remarked that there is a certain excuse for the use of Latin words for in almost all cases they refer to the symbol. Dr. Odling said that Mr. Madan spoke of the convenience which occasionally attached to the use of such a word as “proto-salts,” and to speaking of proto-salts in general. It would be a real aclvantage if all proto-salts were conceived to have the same constitution; but as the word proto-salts does not express the coiistitution any more than -ic and -ous he could not admit that argument to have any weight in favour of the use of such words as proto-and per-rather than of -ic and -ous.He was rather inclined to agree with Mr. Harcourt’s observations in defence of the English. Respecting such words as mono-chloride and bi-chloride of mercury it is quite true that if we use them we mean that the one contains double the quantity of chloriiie in the molecule to the other and not merely double the ratio of the mercury and the chlorine. The President hoped it would not be understood that he insisted on Latin names in preference to the English. When Latin names are more easily modified than English by all means use them; but when such is not the case refuse them. MADAN ON SOME POINTS ETU.It would not be worth while to employ English words instead of the Latin aluminium chromium &c. ; and it should not be argued that because we use English words in some cases that therefore we must use them in all cases. The whole genius of the English language is at variance with such a proposition. We want an intelligible principle to guide us instead of the fixed names which imply particular theories of the constitution of bodies. With regard to -ic and -uus adapting themselves only to one term of a series he conceived that as long as we have to do with the properties of bodies in chemistry tho difference between acid and basic bodies will be one of the chief things to refer to; and if the business of names is to recall the chief properties of bodies he thought it must be an advantage in describing terms of a series to use some name to distinguish those which are not acid from those which are.Professor Voelcker said that in one aspect uniformity of nomenclature has great advantages ; but he was not sure that one and the same chemical compound having two three or four different names was an unmitigated evil. In teaching chemistry he would not object to a substance being called by the empirical name if by this means certain properties were fixed upon the mind of the student by which he became fami- liar with a certain definite substance. He might afterwards be told to call it by another name arid then by a third ; and when he was once familiar with the real nature of the substance it was immaterial whether he knew it by one name or the other.By the same combination haviiig different names the teacher would be able to illustrate the different views entertained by chemists of the constitution of a substance. [P.S. I think we should be justified in considering such names as aluminium &c. to be naturalised English words if indeed they ever were Latin at all. But this is beside the point; exception is taken not to the use of a Latin name qud Latin but to the use of a Latin name where there exists a respectable English name for the same substance. That system of nomenclature seems to me preferable in which there is the nainimum of modification (which might prove a disguise) of the names themselves the necessary variation being gained by prefixes. Take as an instance the iiomencla- ture of the metric weights and measures.-H. G. M.]