Vallet/ of Oodipooj', 267 



in medicine. It consists principally of carbonate of soda, with 

 associated sulphate of soda and chloride of sodium, and is con- 

 sequently a natron. As purchased in the bazaars, it is mixed 

 up with a great quantity of impurities, such as quartz grains, 

 carbonate of lime, &c., the alkaline salts being in the proportion 

 of about one-fourth of the whole. 100 grains of the alkaline 

 salts obtained by crystallization from a solution of impure reh 

 in water, aftbrded me of dry carbonate of soda 32.492. 



I shall not inquire by what chemical process this efflorescence 

 is formed. A certain degree of moisture seems necessary to its 

 development, as also the presence of carbonate of lime, which 

 last very generally exists as a constituent of the soils of this por- 

 tion of India. The felspars and sodalites of the granites, and 

 other compound rocks, might furnish the alkaline basis in abun- 

 dance. This efflorescence must be carefully distinguished from 

 another, consisting principally of chloride of sodium, which is 

 an abundant production of certain extensive tracts in India. 



I shall now proceed to consider the hock-fokmations of the 

 Valley of Oodipoor. Commencing, then, with the surface, our 

 attention is immediately arrested by numerous beds of that sin- 

 gular calcareous deposit well known in India under its native 

 appellation of kunkuk. 



Kunkur is a term applied to an imperfect rock-formation, 

 very extensively distributed throughout Hindustan*. It is a 

 name, however, used very indefinitely by the natives to indicate 

 a variety of substances of distinct origin, which possess nothing 

 in common, except their capability of affording lime for econo- 

 mical purposes. The deposit to which I am about to call your 

 attention, overlies, geologically speaking, all the true rock for- 

 mations as yet discovered in India ; it does not, however, ap- 



• Mr Calder, in his Outline of the Geology of India, has the following re- 

 marks : — " Its (Kunkur's) prevalence is very extensive, although less abun- 

 dant in the southern portion of the peninsula, neither has it yet been observed 

 on the Malabar coast, and in Bengal it appears to be bounded to the eastward 

 by the Gundak river.'* He adds in a note, that " the prevailing laterite of 

 the Malabar coast is characterized by a proportion of calcareous matter." 

 (See Trans. Ph. Class, Asiatic Society, part i. p. 17-) The laterite, Captain 

 Franklin believes to have been formed by " diluvian agency," and it is pos- 

 sible that this rock may be of cotempuraneous origiu with the kunkurs. 



