252 liLlLCTRO-MOTIVE SERIES OF THE METALS. 



In the present paper 1 have endeavoured to show that the 

 Elactro-motive Series .affords a valuable aid to classifying the 

 metals with regard to many of their fundamental chemical pro- 

 perties. The matter is in general not new, but it seems sufficiently 

 important from a teaching standpoint, to be thought out and put 

 into print. It will be found that practically every property of a 

 metal dealing with its tendency to salt formation can be better 

 correlated by means of the Electro-motive Series than by the aid 

 of the Periodic Classification. To the advanced student of 

 chemistry the value of a thorough understanding of the Electro- 

 motive Series is even greater, since fhe ionisation tendencies can 

 ibe expressed in actual figures. It may be that the final classifi- 

 cation for Inorganic Chemistry will be one resting on the prin- 

 ciples of energy. In such an ideal classification every reaction 

 would be characterised by a definite numerical value representing 

 its driving force, instead of by the v,ague term, affinity, or ten- 

 dency, as it has to be at present. Such a system, however, will 

 be based on electrical measureiments, and will be a later develop- 

 ment of the classification, according to the Electro^notive Series. 



Le VaillanT'S Grotto.— In the January issue of the 

 Gcograpliical Journal (vol. 39. pp. 40-47) an interesting descrip- 

 tion of the grotto at Heerenlogement, nearly 20 miles north-west 

 of Clanwilliam, where le Vaillant inscribed his name in 1783, 

 is given by Prof. II. H. W. Pearson. Amongst other illustra- 

 tions the article has a photograph of part of the north wall of 

 the grotto, where, in addition to the name of the celebrated 

 South African traveller, some other well-known names appear, 

 including Andrew Geddes Bain (1854), Baron von Eudwig 

 (T853), and Zeyher (T829). Dr. Pearson remarks regarding the 

 condition of the grotto : — 



" It is used as a shelter for stock, and some of the inscriptions are 

 so worn down by friction that they are now ahnost obhterated, and of 

 the few who have visited it in recent years a considerable proportion have 

 felt impelled to inscribe or paint their own names on the walls at the 

 risk of confusing the earlier and more interesting records. The situation 

 of the cave renders any adequate measure of protection exceedingly 

 difficult, if not nnpossible, and there is every probabiiit>- that before 

 many years have passed, it will have lost the principal tcaturc of the 

 interest which it possesses to-day." 



The names of \^an der Stel, Ecklon, and Zeyher are 

 curiously misspelt m Dr. Pearson's article. 



