Composition of White Light. 



103 



of the work, states that other philosophers, among which, 

 the author is in some instances included, have adopted 

 opinions opposed to it; this contradiction, which must 

 necessarily extend to the branches connected with this im- 

 portant part of the subject, not only indicates a state of un- 

 certainty in science, which it is desirable to remove; but it 

 also presents to the inexperienced reader a source of diffi- 

 culty, which must considerably impede his progress; on 

 both these accounts, and for many other reasons which have 

 been stated in the progress of this inquiry, the question 



claims our consideration. 



Paul Cooper. 



Bawlish, 25th November, 1835. 

 To the Editor of the Records of General Science. 



Article III. 

 Water of the Elton, Dead, and Caspian Seas.* 

 The Elton Sea lies to the east of the Volga, 274 versts 

 (181 \ miles), south from Saratov. Its greatest diameter, 

 from east to west, is 17 (ll£ miles), and its smallest dia- 

 meter 13 versts, (8J miles). 



The specific gravity of the water, at 53|°, is 1*27288, 

 according to Rose. 



Its contents are according to Rose and Erdmann :— 



Chloride of sodium, . . 

 Chloride of potassium, 



Chloride of magnesium, . 

 Sulphate of magnesia, 



Sulphate of lime, . . . 



Sulphate of soda, . . . 



Carbonate of magnesia, . 

 Water and organic matter, 



1000-0 • '. • 1000-00 

 When the temperature of the sea falls, Epsom salt pre- 

 cipitates. Here it is evident that the specific gravity and 

 composition must change with the temperature. The shore 

 of the Elton sea exhibits, in summer, crystals of gypsum 

 and common salt; and, in winter, besides these, Epsom 

 salt, which, in summer, is again dissolved, so that pure 

 • Poggondorff'i Araaleo, xxxv. 169. 



