1840.] Museum of Economic Geology of India. 977 



the same thickness. They should be carefully numbered, both on the 

 specimens themselves, and on the envelope in which they are wrapped ; 

 one copy of the list to which the numbers will refer, should be trans- 

 mitted by dawk, and another placed in the box with the specimens. 



Specimens of slates, with the dimensions, quantity, and rate at which 



Building materials, they Can be obtained ; also of marbles, and building 

 stones, cut into six inch cubes, will be desirable. The expense of quarry- 

 ing and of transport to the nearest water conveyance should be detailed. 

 One side of the cubes should be left to exhibit the exposed or weather- 

 ed surface of the rock, the others roughly chiselled. The cubes of 

 marble may be polished, except on their under surfaces. 



The quality of water at the issue of springs, and the sediment depo- 

 Examination of ^^^^^ ^y them, should be particularly noticed, as they 

 springs. Pise to the surface, generally, at some fault or disloca- 



tion of the strata, and will probably be imbued with matter derived from 

 the metallic bodies with which they may have been in contact. Thus, 

 water percolating through a bed of coal has often its surface coated 

 with a thin film of oxide of iron, derived from the decomposition of 

 iron pyrites, diffused through the coal. When traces of coal are dis- 

 covered, it would be very desirable to transmit pieces of the strata of 

 rock with which it is supposed the coal is associated, stating the extent 

 of surface which the deposit is believed to cover, and the depth at 

 which it is found ; accompanied, if possible, by a vertical section, with 

 figured dimensions of the accompanying beds. 



Descriptions of native mining operations, and complete series of 



Operations of mi- Specimens showing the processes followed in the re- 



ning and reduction of ductiou of ores, in their various stages of progress, 



°^^^' to the metallic state, will be highly valued, when 



accompanied by explanations of the modes of procedure. 



Specimens of soils should always be forwarded in connection with 

 communications, and inquiries of agricultural interest. 



Soils being generally the upper decomposed portions of subjacent 

 Soils. mineral substances, whether hard rocks of various kinds, 

 or clays, marls, sands, &c., mingled either naturally or artificially 

 with vegetable and animal matter, it becomes very desirable in col- 

 lecting specimens of them, that they should be accompanied by 

 others of the hard rocks, clays, marls, sands, &c., on which they rest ; 



