GEOLOGY. 



27 



On this subject Dr. Warth remarks :* " the analysis seems to justify 

 " expectation. The natives assert the Kohat salt to be less saline to 

 " the taste than the Cis-Indus, and it appears they are right as far as 

 " the admixture of foreign salts is concerned ; it is the latter which give 

 " a more intensely saline taste to the rock-salt of the Cis-Indus mines." 

 <( Annexed is a comparative table of the chemical constitution of the 

 " Kohat salt as compared with that of the Mayo Mines in this respect. 





No. 1. 



No. 2. 



No. 3. 





Xohrft salt 

 analysis above. 



Pure trade salt, 

 Mayo Mines. 



Impure waste salt, 

 Mayo Mines. 



Insoluble matter 



Sulphate of lime 



Magnesia ...""l 



Calcium ... y 



1 



Sulphates, &c. ...J 



0-5 

 0*0 



Trace. 

 0-8 



17 



1-0* 

 2-5 



2*5 



" From this it is seen that the Kohat mineral contains no foreign salts 

 " at all, while the best Cis-Indus salt contains almost £ per cent. Further, 

 " the Kohat salt contains a considerable amount of sulphate of lime and 

 " of insoluble matter, approaching in this respect the bad salt (No. 3 above) 

 " of the Mayo Mines. Thus the salt of Bahadur Khel is purer than 

 " that of the Mayo Mines as regards foreign salts, and less pure as regards 

 " insoluble matter and sulphate of lime." 



Stratification. — Except where the salt is very massive and crystal- 

 line, its stratification is generally well marked, though sometimes con- 

 cealed in the eastern quarries partly from the homogeneous structure 

 and partly by the marks of the miners' picks. The slight admixture 

 of clay at the western exposures favours the recognition of the lines of 

 bedding which are frequently as clearly seen as in any other rock, and 

 which also determine the local method of working. 



* MS. letter, May 1874. 



( 131 ) 



