540 



NATURE 



[April Sy 1888 



That the two signs for the royal name are not engraved 

 immediately above the cone may have resulted from the 

 space above the king's right arm being too contracted. 

 There is another change in the characters on the king's 

 right side which is noteworthy. It will be seen that both 

 the ideograph of the country and the numerals giving the 

 name are inverted. On the left side of the king the 

 characters were to be read from left to right of the reader, 

 but on the right side they are to be read from right to left. 

 This change is in accordance with the boustrophedon 

 manner of writing previously mentioned, but it is a 

 change which seems totally incompatible with the idea of 

 forgery. 



( To be continued^ 



ELEMENTS AND META-ELEMENTS. 



THE President of the Chemical Society, in his address 

 at the anniversary meeting, has further developed 

 views which he had already propounded in his address to 

 Section B of the British Association at Birmingham, and 

 in a subsequent Friday evening lecture at the Royal 

 Institution. He would have us believe that the atoms of 

 an element are not all precisely of one absolute pattern ; 

 that atomic weights, in fact, are not constants, as gener- 

 ally supposed ; but that we must regard each element as 

 a species of which many varieties exist almost infinitely 

 more like unto each other than to the atoms of any other 

 approximating species of element ; and that what we term 

 the atomic weight is but a mean value around which the 

 actual weights of the individual atoms of the species 

 range within certain limits. Could we separate atom 

 from atom, we should find them varying in weight within 

 very narrow limits on each side of the mean. 



Mr. Crookes supports his arguments by a wealth of 

 illustration culled chiefly from his own unique experience ; 

 and, whatever the ultimate intrinsic value to science of 

 his hypothesis, there cannot be a question that the study 

 of the transcendent problem of the nature of the elements 

 will have gained greatly in fascination by its promulga- 

 tion ; that lines on which such study may be carried on 

 will have been indicated ; and that he will have light- 

 ened the inexpressibly wearisome labours of fractiona- 

 tion by casting around them the poetic play of fancy. 

 The subject is of such importance that it appears desir- 

 able to consider the position which chemists may fairly' 

 take up, and from which it is permissible to criticize the 

 arguments that have led to the suggestion of the 

 existence of meta-elements. 



Apart from the higher interest which Mr. Crookes has 

 now infused into them, his researches on the rare earths 

 will ever excite admiration in all who study them, as 

 models of scientific investigation ; and they will afford 

 undying testimony to his determination and patience in 

 search of truth, as well as to the incomparable fertility 

 of resource in experimenting of which he is possessed. 

 Among the individual observations are many of a most 

 suggestive and striking character which, sooner or later, 

 must claim attention ; but it cannot be denied that the 

 data are as yet insufficient for their exact interpretation. 

 This is true also of Kriiss and Nilson's remarkable obser- 

 vations ; indeed, it may be questioned whether their 

 results all admit of the absolute interpretation which they 

 are inclined to put upon them. In the paper in which 

 the omnipresence of samarium is demonstrated, in giving 

 an account of the many anomalies which he encountered 

 in his search for x — the substance characterized by an 

 orange-coloured band in the phosphorescent spectrum, 

 and which subsequently turned out to be samarium — 

 Mr. Crookes tells us how he came to the conclusion 

 that samaria {x), which of itself gave little or no 

 phosphorescent spectrum in the radiant-matter tube, 



became immediately endowed with this property by ad- 

 mixture with certain other substances — lime, for example 

 — which substances likewise of themselves had no 

 power of phosphorescing with a discontinuous spectrum. 

 Many substances were found effective ; and there was 

 a general resemblance between the spectra, but nearly all 

 of them differed from one another in detail. Mixtures 

 of samaria and yttria gave spectra differing to a very 

 marked extent according to the proportions in which the 

 two substances were present. All who take note of these 

 observations must agree that they are of a most remarkable 

 and significant character : they certainly leave no room for 

 doubt as to the necessity of exercising the utmost caution 

 in inferring the absence or presence of particular sub- 

 stances from spectral appearances and changes. Judging 

 from Mr. Crookes's obsei-vations, and from our general 

 knowledge of the rare earths, it would almost appear that 

 they have the power to form double oxides akin to double 

 salts, and the effect on the spectrum produced by asso- 

 ciating one oxide with another may be compared with the 

 somewhat similar effect of a solvent on the spectrum of a 

 coloured substance. The part that such double oxides 

 perhaps play appears as yet to have been left out of con- 

 sideration. It is desirable also to take into account the possi- 

 ble presence of double salts, and of their influence on the 

 spectrum, before deciding as to the bearing of Kriiss and 

 Nilson's observations. 



Reference is made by the President of the Chemical 

 Society in his address to Carl Auer's investigation of 

 didymium. Now the differences between Auer's neo- and 

 praseodymium — the reputed constituents of didymium — 

 are very marked ; but as yet unfortunately we have no 

 information respecting their atomic weights. This is true 

 also of the various reputed constituents of the rare earths 

 studied by Mr. Crookes and Kriiss and Nilson. Until 

 such information be forthcoming, the suggestion that 

 what is commonly regarded as the atomic weight of an 

 element is but an average value, therefore, can only serve 

 to direct attention anew to the extreme importance of the 

 most exact and exhaustive study of atomic weights. 



What is called yttria, according to Mr. Crookes (Proc. 

 R.S., xl. 506) is a highly complex substance capable of 

 being separated into several simpler substances, each of 

 which gives a phosphorescent spectrum of great sim- 

 plicity, consisting for the most part of only one line. 

 Now, supposing that the several constituent meta- 

 elements of ordinary yttria be found when isolated to 

 differ almost imperceptibly from each other both in 

 chemical properties and in weight, yet the spectral differ- 

 ences will admittedly be very marked — as marked per- 

 haps as are the differences between elements which 

 exhibit very diverse chemical properties and atomic 

 weights ; and it will be illogical to deny to these meta- 

 elements the right to rank as elements proper — as distinct 

 species, not mere varieties. 



Why, then, does Mr. Crookes think it inadmissible in 

 the elementary examination to open the doors so wide 

 that the number of admissions will be limited only by the 

 number of applicants? It is because bethinks that the 

 periodic system of classifying the elements offers an 

 insuperable barrier to this course. Undoubtedly, if 

 this were granted, there would be little choice left 

 us ; but can it be granted ? We think not. The 

 scheme at present accepted is after all but a very im- 

 perfect and provisional classification. The successional 

 order of the elements in the horizontal series is indeed 

 determined in all cases in which the atomic weight is 

 known with a sufficient approximation to truth ; and in 

 certain cases where the properties are clearly marked it is 

 possible to assign the true position in the order of succes- 

 sion to an element even when the atomic weight is very 

 inexactly ascertained ; tellurium is an example, having 

 been placed before iodine long ere its atomic weight was 

 ascertained to be lower and not higher than that of 



