284 THE KINETIC THEORY OF GASES. 



hydrogen being- taken as 1. Similar reasoning proves the atomic 

 weight of argon to be 40, from the known fact that it is twenty times 

 as heavy as hydrogen. Moreover it is noteworthy that the difference 

 between these numbers 40 and 4 is 36. 



Mr. John Newlands, whose recent death is deplored by the scientific 

 world, as long ago as 1868 brought forward what he termed a "law of 

 octaves."" It consisted in arranging the numbers which represent the 

 atomic weights of the elements in seven rows, beginning again with the 

 eighth element, so that its atomic weight occupies a position in the 

 table below that of the first, the ninth below the second, the fifteenth 

 again below the first, and so on. The reproduction of three of such 

 rows will make the meaning clear. 



Li 7 Be 9-2 B 11 C 12 N 14 O 16 F 19 



Na 23 Mg 24-3 Al 27 Si 28 P 31 S 32 ■ CI 35-5 



K 39 Ca 40 Sc 44 Ti 46 V 52 Cr 52-5 Mn 55 

 &c. &c. 



The elements appear in this table in groups, of which the indi- 

 vidual members closely resemble each other, often in appearance, and 

 always in the nature of the compounds they form with other elements. 

 Thus, to take the first column, the three elements, lithium, sodium, 

 and potassium, together with others not here produced, but which 

 occur later on in the table, rubidium and caesium, are all white waxy 

 metallic solids, easily cut with a knife, tarnishing rapidly in contact 

 with ordinary moist air, and forming compounds which themselves 

 present the greatest resemblance to one another. Now, in Mr. New- 

 lands's view, the fact that the eighth element resembles the first 

 suggested an analogy with the musical scale, where the tones can be 

 similarly classified, each eighth note of the major scale reproducing, 

 as it were, the fundamental note. In the ordinary notation, the name 

 C refers to many notes, separated from each other by octaves. The 

 analogy may be regarded as fanciful, and in the light of more modern 

 work the word "octave" is here inapplicable; and this perhaps over- 

 strained analogy did much to discredit Mr. Newlands's views in the 

 eyes of the leading chemists of the day. It was not until 1868, when 

 the late Prof. Lothar Meyer, and Professor Mendeleef independently 

 arrived at a similar arrangement, that the attention of chemists was 

 recalled to the subject, and the justice of Mr. Newlands's ideas was 

 acknowledged. The somewhat tardy award of a medal by the Boyal 

 Society placed in its true position the work of Mr. Newlands, and was 

 regarded as an act of justice by his friends. It is deeply to be regretted 

 that his recent death has removed from our midst a man so kindly 

 and so alive to every advance in science. 



The elements helium and argon, if they be really elements and not 

 compounds (and there is no reason to doubt their elementary nature), 

 should find places in this table, now known as the "Periodic Arrange- 

 ment of the Elements." And confining our attention to only a few of 



