564 J. G. Malcolmson, Esq., on the Fossils of 



specimen, however, procured from the water of a deep well near London, passing through the 

 London clay into the chalk, which I received from Professor Daniell, contained the carbonate ; 

 but as the sesquicarbonate is decomposed by a low heat, no inference can be founded on the ex- 

 amination of specimens obtained, as this was, from the boiler of an engine. 



The absence of Lime in the water of the Lonar Lake is a remarkable circumstance, but easily 

 accounted for, as the sesquicarbonate of soda and the water itself precipitate the sulphate and mu- 

 riate of lime, notwithstanding the mutual decomposition they undergo when in a semifluid state. 

 The Lake of Ourmia, in Persia, is stated by Dr. Marcet to contain no lime, although of a specific 

 gravity of 1165'07, and abounding in sulphates and muriates. This appeared very remarkable 

 in an inland sea nearly 300 miles in circumference, situated in a volcanic country. On referring 

 to the works of travellers*, it appeared that the streams flowing into it abounded in lime, which 

 is deposited in large quantity in the form of a beautiful travertine. The lake is shallow, and at 

 certain seasons much of it is nearly dry ; the water is clear and transparent, but the mud of the 

 bottom is loaded with sulphuretted hydrogen, and thick layers of salt, formed in it under the 

 water, are redissolved on any agitation. No fish can live in it. All these phenomena are exact 

 counterparts of those exhibited at Lonar, but no information is given as to the salt collected from 

 its saline mud, except that Sir John Malcolm states, the salts are bitter and different from those 

 of the sea. I am, therefore, strongly impressed with the conviction, that sesquicarbonate of soda 

 is formed from its waters as at Lonar, and precipitates the lime. Dr. Marcet, however, has 

 given, in the Philosophical Transactions for 1819, the results of an examination of a small quantity 

 of this water, which he states to be as follows : 



1. Precipitate from 500 grains of the water by nitrate of silver 237"0 



2. By nitrate of baryta 66-0 



3. Magnesian precipitate by carbonate of ammonia and phosphate 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 pre- 

 cipitate 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 f- 



The Lake of Ourmia, like that of Lonar, contains potash, which I did not 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 surrounding precipices. The sulphuretted hydrogen adhering to the clay 

 has been supposed to be derived from volcanic sources, but I have observed 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 sulphur and, 

 I have reason to believe, sulphuric acid, although on this point the proof is defective. The effect 

 is to be ascribed to the decomposition 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 ad- 

 hesion. Similar actions have gone on in former times in the alluvium on which the city of Ma- 

 dras stands, and probably in more ancient deposits t. 



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



* Sir John Malcolm's History of Persia ; Sir Ker Porter's Travels ; Ouseley's Travels ; Jour- 

 nal of the Geographical Society, vol. iii. &c. 



t 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, which the sesqui- 

 carbonate would not. 



J 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 between the valley of 

 Berar and the Nerbudda, I have found to contain sulphuretted hydrogen and muriate of soda, 

 without lime. 



i 



