On the Geological Structure of the AlpS) Carpathians^ Sfc. 207 



fusion and separation of the siliceous matter '^Gl, gave 85'03 

 per cent. 



I could detect no platinum, palladium, or any of the metals 

 usually combined with them, such as osmium, iridium, &c., in 

 this gold ; but the small amount at my disposal would not 

 allow me to employ a quantity sufficient to enable me to pro- 

 nounce absolutely on the absence of any traces of them. 



The remark of Dumas ( Traite de Chimie appliquee auxArts, 

 tome iv, p. 434-), that the proportions of gold and silver are so 

 nearly constant in the mineral from the same locality {gisement) 

 that the assayers know the composition when they have ascer- 

 tained the precise locality which furnished it, is not confirmed 

 by the above analyses, in which the gold varies from 8.5 to 90 

 per cent., nor indeed by those of G. Rose, of four specimens of 

 gold from the same spot (Boruschka), which contained re- 

 spectively 5*23, 8-35, 9*02 and 16*15 percent, of silver. 



This gold has very nearly the colour of the pure metal; 

 after fusion however it becomes of a brass-yellow colour. This 

 fact, together with the appearance of the grains under the mi- 

 croscope, would almost induce one to believe that the surface 

 of the grains was purer or ^^Jiner" than the interior, and that 

 a portion of the silver had been removed from the surface by 

 some chemical agent in nature. Prof. G. Rose, at the end of 

 his memoir already quoted, refers to the opinion prevalent 

 both in the Ural and at St. Petersburg, that the gold from the 

 washings is purer than that from the mines, and appears suc- 

 cessfully to combat both this opinion and the speculations of 

 Ferussac, who would account for it by the action of sea-water, 

 &c.; but I must refer the reader to his memoir for his argu- 

 ments, which are of great interest. 



XXX. On the Geological Structure of the Alps, Carpathians 

 and Apennifies, more especially/ on the transition fro/n SecoU' 

 daryto Tertiary Types and the existence of vast Eocene De- 

 posits in Southern Europe. By Sir Roderick Impey Mur- 

 CHisoN, F.E.S., V.P.G.S.i <^c.; Mem. Imp. Ac. Sciences of 

 St. Petersburgh, Corresp. Member of the Academies of Paris, 

 Berlin, Turin, Sj-c* 



nPHIS memoir, chiefly the result of the author's last excursion on 

 the Continent, consists of three parts, the first of, which is an en- 

 deavour to bring up to the present standard of knowledge the work 

 on the Eastern Alps, published long ago by Prof. Sedgwick and him- 



* Abstract of a Memoir read before the Geological Society Dec. 13. 1848 

 and Jan. 17, 1849. ' 



