1836.] the Sdmar lake salt-works. 805 



A circumstance of chief importance elicited by Lieut. Conolly's 

 specimens, is the presence of the carbonate and sulphate of soda 

 in considerable abundance among the saline products of the Sambhur 

 lake. The greater part of the substance described by the manu- 

 facturers as refuse or scum, which is stated to be thrown away as 

 useless, turns out on analysis to be carbonate of soda, contaminat- 

 ed with sulphate and muriate ; and it is well deserving of inquiry, 

 whether the discovery of so extensive a store of natron in a state of 

 great purity, may not be turned to profitable account. In all the 

 strata cut from the neglected kiydrs the carbonate is seen overlying 

 the mixed sulphate and muriate, of an efflorescent snowy consistence. 

 Sometimes the formation of the salt is prevented by its abundance as 

 (in A 4, 5, 6) ; No. 5, 1 find on analysis to contain 40 per cent, of 

 carbonate, with 30 of each of the other salts — and a little care in 

 separating the crystals of these 'would leave it nearly pure. 



Spicular crystals resembling nitre are seen in some of the speci- 

 mens (All); they bear a very small proportion to the general mass. 

 It is but necessary to refer to Mr. Stephenson's examination of other 

 specimens, to form a clear idea of the conditions best suited for the 

 separation and collection of the different salts ; thus in the old desert- 

 ed pits (B No. 1), the sulphate is obtained nearly pure : in A 6, 10, 

 it is mixed with carbonate ; in A 5, the latter predominates. As for 

 the muriate, from its inferior solubility, this salt is readily separated 

 in a state of purity from the brine. 



The small proportion of lime in the earthy residue of A 1 , from the 

 bed of the lake, rather militates against the expectation entertained 

 by Lieutenant Conolly from native report, of a subjacent stratum of 

 this mineral. 



The points now wanted to complete Lieutenant Conolly's descrip- 

 tion of the Sambhur salt manufacture, and the questions naturally in- 

 duced from the information he has already given, are : 



1. A topographical account of the lakes, their extent, general 

 depth, position relatively to adjacent plains, sands, or hills. 



2. The extent of the manufacture, produce, possible increase, price, 

 and other statistical data. 



3. Whether the carbonate and sulphate are worked and used ? 

 the quantity and price of these. 



4. The exact process followed by the native manufacturers or 

 collectors. 



5. The specific gravity of the water, both of the lake and of the 

 brine pits, at different seasons ; which may be found in the absence 

 of the means of determining it on the spot, by bottling off a portion 



