Lakes 309 



perature observations to show the effect of a vertical sun on 

 large bodies of water at a moderate elevation, and removed 

 from the disturbing influence of oceanic circulation. 



As might be expected, in salt lakes which have no overflow, 

 the yearly rise and fall is often considerable. In the Great 

 Salt Lake in Utah, the greatest depth of which is 56 feet, 

 changes of level are accompanied by great changes in water 

 surface, and also in saltness of water. In the rainy season the 

 Dead Sea stands ten or twelve feet higher than in the dry 

 season. The table, p. 310, shows the chemical composition 

 of the waters of various salt lakes, that of the sea-water in the 

 Suez Canal being added for comparison. 



This table embraces examples of several types of salt lake. 

 In the Kokonor, Aral, and open Caspian seas we have examples 

 of the moderately salt, non-saturated waters. In the Kara- 

 bugas, a branch gulf of the Caspian, the Urumieh, and the 

 Dead Sea we have examples of saturated waters containing 

 principally chlorides. The Van Sea is an example of the 

 alkaline seas which also occur in Egypt, Hungary, and other 

 countries. Their peculiarity consists in the quantity of car- 

 bonate of soda dissolved in their waters, which is collected by 

 the inhabitants for domestic and for commercial purposes. 

 The chemical reader will be struck by the quantity of magnesia 

 'lissolved in water which contains so much carbonate of 

 soda. The analysis in the table is by Abich, quoted by Schmidt 

 in his interesting "Etudes Hydrologiques," published in the 

 Bulletin de I' Academic de St Petersbourg. Another analysis by 

 De Chancourt, quoted by Bischof, omits all mention of sulphate 

 of magnesia, but inserts the carbonate. 



The limits of this article do not admit of the discussion of 

 tin- many interesting phenomena connected with salt lakes. 

 With regard, however, to .1 former connection of the Caspian 

 with the Black Sea, which has been so often suggested, it seems 

 improbable, both on chemical and on physical grounds, that 

 were ever connected as seas, that is in the same way as 

 tli-- Black Se :inected with the Mediterranean; but. it 



we con-id, r tin- topography of the Caucasus district, we see that 

 the lowest summit N-vel of the land between the two seas is 



