X 



162 Silt lield in suspension in the Hooghly. [No. 2, 



Kunkur from the leach at Kedgeree. 

 This is a true kunkur* as to external form, and may at a little 

 distance be easily mistaken for one of the common iron laterites, to 

 which indeed it in some measure approaches ; for singular to say it 

 contains a mere fraction of two or three per cent, of lime ! and is 

 in fact a loose and coarse-grained, siliceous sandstone kunkur, of 

 which oxide of iron and not lime forms the cohesive element. 

 "When we recollect that this is in progress of formation on the shore 

 of the estuary of a river, the waters of which are abundantly 

 charged with lime and the tidal water, with magnesia, while the 

 v oxide of iron forms a mere trace in it, it is certainly a most singular 

 Geological fact and one which may give rise to many speculations, 

 ' For the present I only note it and that a fair average of it gave in 

 100 parts as follows. 



Earthy Silicates, 84.75 



Carbonate of Lime, 2.50 



Carbonate of Magnesia, 0.61 



Peroxide of Iron, 12.00 



99.86 

 Loss, „ 0.14 



Total, 100.00 



Dredgings from Lloyd's Channel. 

 These are principally a fine micaceous sand which gives but a 

 very little effervescence, and thus contains but an exceeding small 

 proportion of carbonate of lime. It separated naturally in the bot- 

 tle into two parts, of which the lower one was the sand above 

 described, and the upper one a black fetid mud ; so strongly impreg- 

 nated with sulphuretted hydrogen, that it immediately and strongly 

 discoloured silver foil placed in it, thus shewing that the vast 

 amount of decomposing animal matter of which the Hooghly is, we 

 know, made the receptacle, is by a wise provision of nature, so to 

 say, imprisoned beneath the waters ! where it doubtless serves as 

 food for millions of the inferior animals. 



* Using the word in the native sense, Jconhra, any thing rough, jagged or puck- 

 ered ; for it is applied both to concretionary limestone and also to the ferruginous 

 concretions usually called by us Laterite. 



