1840.] 



of the Great Basaltic District of India. 



91 



1. Precipitate from 500 grains of the water hy nitrate of sil- 

 ver 2370 



2. By nitrate of baryta 66 0 



3. Magnesian precipitate by carbonate of ammonia and phos- 

 phate of soda 10'5 



and he infers, that although it contains no lime, it yields twenty times as 

 much sulphuric acid and six times as much muriatic acid as sea water 

 does. But Dr. Marcet had only 150 grains of this water to operate on, 

 and merely gives in a tabular form, along with many specimens of sea 

 water, the quantity of precipitate caused by the various reagents ; and 

 there is no evidence that the precipitate from muriate of baryta was not, 

 in part, caused by carbonate of soda. It is, at all events, worthy of the 

 inquiry of future travellers*. 



The Lake of Ourmia, like that of Lonar, contains potash, which 1 did 

 not detect in the springs running into the latter, but its source is no 

 doubt in the decaying (and when I visited it, burning) trees on the sur- 

 rounding precipices. The sulphuretted hydrogen adhering to the clay 

 has been supposed to be derived from volcanic sources, but I have ob- 

 served the same phenomenon in the salt water inlets along the Indian 

 coast, wherever the bottom contained argillaceous and carbonaceous 

 matter ; and it even goes so far as to form considerable quantities of sul- 

 phur and, I have reason to believe, sulphuric acid, although on this point 

 the proof is defective. The effect is to be ascribed to the decomposi* 

 tion of the sulphates of the water by the carbon ; and the clay probably 

 only prevents its passing off into the air or mixing with the water, by the 

 power of adhesion. Similar actions have gone on in former times in the 

 alluvium on which the city of Madi'as stands, and probably in more 

 ancient depositsf. 



The ancient crater of Lonar seems never to have been an active erup- 

 tive vent, as no scoriae or lava currents can be traced around its margin, 

 which is too distinct and unaltered to admit of any probability of these 

 having been subsequently removed by denudation. A certain degree of 

 forcible elevation was sustained by the margin of the lake, when the 



• If a carbonate exists in the water, it must be of the same composition as that of 

 Fezzan, Maracaybo. and Lonar, as the carbonate "would precipitate the magnesian salt, 

 vrhich the sesquicarbonate would not. 



+ No sulphuretted hydrogen can be detected in the water of the springs running into 

 the lake. The hot spring of Anhoni Simhoni, in the sandstone and basaltic district be- 

 tween the valley of Berar and the Nerbudda, I have found to contain sulphuretted hy- 

 drogen aad muriate of soda, without lime. 



