302 Scientific Intelligence — Geology. 



in^ the valley of Sakaria, and penetrating into the Gulf of Nico- 

 media, by way of Sabandja. M. Ilommaire has, therefore, taken 

 the level to determine the height of the hills which separate the basin 

 of Sabandja from the Propontis. He has found that the least ele- 

 vated point reached an elevation of 40^*99 above the level of the Gulf 

 of Nicomedia. The Bosphorus being closed, the waters of the Black 

 Sea might then rise, flow above the plains of Manitch, and unite in 

 the Caspian Sea, without finding any issue into the Sea of Marmora. 

 Such a junction could not, perhaps, take place in the present day, in 

 conscc[uence of the changes Mhich are taking place in the rivers. 



The same phenomena which M. Hommaire has remarked on the 

 northei'n shores of the Black Sea, he has again found on the coast of 

 Bulo-aria, Romelia, and Anatolia. Everywhere there exists traces 

 of a greater elevation of level in the waters of the Black Sea. These 

 traces consist of modern deposites rising everywhere nearly to the 

 same height, rarely exceeding from 25 to 30 metres, and containing 

 uninjured marine shells, all the species of which now live in the 

 Black Sea. Unless we suppose a complete and regular i-ising upwards 

 of all the countries surrounding the Euxine and the Sea of Azof, pos- 

 terior to all the geological revolutions hitherto indicated, a supposition 

 which, after his own observations, M. Hommaire considers scarcely 

 admissible, we must necessarily have recourse to the notion that the 

 Bosphorus was anciently closed up and burst forth from its boun- 

 daries. 



M. Hommaire has determined the saltness of lake Van. The 

 densimeter of M. Collardeau gave 102, water being 100. The me- 

 thod by evaporation gave 102, 029. 



He concludes by giving the result of his observation, and his cal- 

 culations of the following latitudes :— 



10. Decomposition of Rocks. — M. Ebelmen's memoir on the sub- 

 ject contains new analyses, made by the author, of rocks in a state of 

 decomposition under the influence of atmospheric agents. In deter- 

 mining in this way the nature and proportion of the elements which 

 disappear by decomposition, the author has endeavoured to confirm 

 the conclusions of a former work. By the comparative analysis of the 

 unchanged and altered rock (consisting of trap, called grey-stone, from 

 the neighbourhood of St Austel in Cornwall, and basalt from the 

 vicinity of Linz), he has ascertained that the silex, lime, magnesia, 

 the oxide of iron, in certain cases, and the alkalies, have a tendency 



