August i8, 1910] 



NATURE 



LETTERS TO THE EDITOR. 

 {I'he Editor does not hold himselj responsible jor opinions 

 expressed by his correspondents. Neither can he undertake 

 to return, or to correspond with the writers of, rejected 

 manuscripts intended for this or any other part o/ Nature. 

 No notice is taken of anonymous communications.] 



Wiltshireite : a New Mineral. 



The dolomite quarry near Binn (Vulais) affords such a 

 iarge variety of grey sulpharseiiites, mainly of lead and 

 topper, that a new one is received with much hesitation ; 

 but a crystal recently obtained at Binn gives results which 

 leave little doubt as to its independent character. The 

 specimen consists of a number of very small crystals aggre- 

 gated together in parallel orientations, and a single well- 

 defined image is obtained from several minute end-lacets. 



The crystal belongs to the oblique system. The zone of 

 _pinakoids consists ol smooth faces, 201, 302, 101, 001, and 

 ioi, which give good images. Two other important zones 

 are placed symmetrically on opposite sides of the symmetry- 

 plane; they sliow the forms 522, 211, iii, 122, oil, in, 

 and others. Tlie faces, placed vertically, are striated 

 parallel to their zone-axis, and give very imperfect images, 

 save when they are obtained across the zone ; the forms 

 are 100, 310, 320, 010, and some others. The elements 

 adopted are: — 100:001 = 79° 16'; 100:101=48° 473'; and 

 on : 001 = 46" 2oj'- 



I propose for it the name wiltshireite, after the late 

 Prof. Wiltshire, who was a most generous benefactor to 

 the Cambridge museums of mineralogy and of geology. 



Cambridge, August 13. W. J. Lewis. 



The Nomenclature of Radioactivity. 



.'\ FEW years ago I wrote to N.iture (vol. Ixxvi., p. 638) 

 protesting against the proposal of Prof. Boltwood to call 

 the member of the uranium-radium series, which he had 

 just discovered, by the fanciful name of " ionium " instead 

 of by a name based upon the system of nomenclature 

 started by Sir William Crookes and extended by Prof. 

 Rutherford. Prof. Rutherford replied (p. 661) that the 

 lime had not yet cozne for the establishment of a definite 

 system of nomenclature, but that he hoped that some day 

 " physicists and chemists would meet together to revise 

 the whole system." After such a decision from the first 

 authority on the subject I could do nothing but collapse ; 

 but there are three reasons why the present moment seems 

 to me suitable for a renewal of vitality. 



First, Prof. Rutherford said that he thought it un- 

 desirable (I did not agree with him) to fix a method of 

 naming until nearly all the products to be named appeared 

 to have been discovered. I believe it is about two years 

 since the last new member was added to any of the series 

 previously known. Second, there is at hand an admir- 

 able opportunity for the meeting together of physicists 

 and chemists which he suggests — the congress at Brussels 

 next month. Third, it appears to me that reform has 

 been made urgent by a particularly disastrous attempt at 

 unsystematic nomenclature. In a recent number of tlie 

 Comptcs rendus Sir William Ramsay, after determining 

 more certainly the molecular weight of radium emanation 

 by a beautiful experiment, and finding the result to con- 

 firm his suspicion that this substance belongs to the group 

 of inactive gases, proposes that it should henceforward be 

 called " niton." (By a curious oversight, he suggests that 

 the symbol should be " Ni," which is, of course, already 

 appropriated.) 



The purpose of a systematic nomenclature is to express 

 relations between the objects named. So long as elements 

 were regarded as wholly independent objects, the practice 

 of naming them, as if they were dogs, on purely senti- 

 mental grounds was more or less justifiable, for there 

 were no relations between them to express. As soon as 

 the first general relation between the elements, the periodic 



law," was discovered, "a systematic nomenclature was 

 desirable, and some feeble steps tow^ards if were taken. 

 ^\ ith the discovery of the radio-active elements, the whole 



NO. 2I2q, VOL. 84] 



importance of which lies in their relations to each other, 

 a complete system becomes a necessity. 



Let me take an analogy. If Sir William Ramsay takes 

 a house in the country, where buildings are scattered at 

 random, nobody will care what he calls it. But if he takes 

 a house in the street of a city and proposes to replace the 

 number on the door by " Bellevue," or " Glencoe," or 

 " Chatsworth," or any other of the names dear to lodging- 

 house proprietors, he will meet with scant sympathy from 

 the postal and municipal authorities. His case will not 

 be much better if, like Prof. Boltwood, he builds a house 

 where there was none before, instead of merely improving 

 one that existed already. 



The only defence Sir William Ramsay can offer for his 

 proposal is that it is in accordance with chemical, if not 

 with radio-active, nomenclature. If this were true, the 

 question would arise whether the chemical or the radio- 

 active properties of the element were more important ; I 

 cannot conceive that anyone would doubt the superior 

 interest of the latter. But it is not true. The name which 

 he proposes, interpreted according to chemical usage, 

 suggests (1) that the substance is non-metallic, and (2) 

 that it is not an inactive gas. It suggests (i) because it 

 ends in -on ; it suggests (2) because the root is Latin. 

 The only names of elements ending in -on which are not 

 those of inactive gases — carbon, boron, silicon — all have 

 Latin roots ; all the names of inactive gases have Greek 

 roots. By the choice of a Latin name, radium emanation 

 is placed in the former and not in the latter group. Surely, 

 also, when in the names of the argon group we have a 

 rare instance of terms, invented recently, which are 

 linguistically correct, it is a crime to spoil the group by 

 the intrusion of one of those philological barbarities the 

 toleration of which does so little credit to the general 

 intelligence of men of science. I do not know whether 

 Sir William Ramsay has been troubled by the fact that 

 the most familiar Greek w^ord for " bright," aryits. is 

 clearly inadmissible, but I am sure that any classical 

 scholar could provide a suitable synonym. 



I am not going to propose a system of radio-active 

 nomenclature, for, if I succeeded in attracting any atten- 

 tion, people would then confine themselves to abusing my 

 system, and not to considering whether any system is 

 desirable. But I should like to point out the faults of 

 the present method, and direct attention to two possibilities 

 for a new method. 



The faults of the old system are (i) that it does not 

 permit of interpolation ; (2) that it separates systems which 

 are now known to be connected, such as uranium and 

 radium ; (3) that it lays far too much stress on the acci- 

 dental fact that some of the elements are gases at ordinary 

 temperatures ; and (4) that it is anomalous in making X 

 precede A. 



The first possibility for a new system is to order the 

 elements by numbers, and not by letters. Such a system 

 admits of indefinite interpolation ; between i and 2 there 

 can be interpolated, first, the q terms i-i-i-q, then the 

 qo terms i-oi-i-qq, and so on. The second possibility 

 lies in the fact that the rays emitted by the elements are 

 distinguished by single letters, so that the radiation from 

 an element might be expressed by the terminations -o (for 

 no rays), -a (for o rays), -ob (for 18 and 7 rays only), -ab 

 for all kinds of rays. Of course, the form " radiob " 

 would have to be avoided on account of prior rights 

 (Nature, vol. Ixxii., p. 7q), and modification would be 

 needed if the additional termination -g were rendered 

 necessary by a discovery that /3 and 7 rays could occur 

 separately. 



A scientific system of names need not displace com- 

 pletely such well-known terms as " radium " any more 

 than the appropriate name, according to the excellent 

 svstem of organic chemistry, has displaced that of (s.iy) 

 " indigo." But I maintain strongly that every radio- 

 active element ought to have a name discoverable from 

 its properties, and a name from which, conversely, its 

 properties mav be discovered. Such a olan would not 

 help greatly those who are so accustomed to radio-active 

 \vork that the association of a fanciful name with definite 

 properties is intuitive, but it would be an inestimable boon 

 to those who now, when they hear of " mesothorium,'' 



