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MINEKAIX)GY. 



[Sect. VIII. 



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hazardous to attempt the wet method of investigatioiu but 

 by a little practice, much knowledge may be acquired by 

 the blowpipe, or what may be termed the dry method. 

 Works are especially dedicated to this mode of inv 



stiga- 



tion. As these may not be at hand, Mr. Warinoton 

 Smjth, Mining Geologist of the Geological Survey of the 

 United Kingdom, and who has long employed the blow- 

 pipe in his researches, has prepared the following short 

 notice of the mode in which this instrument may be ren- 

 dered useful : 



The ordinary blowpipe is so well known as scarcely to need descrip- 

 tion, Varioiis forms have been recommended by their inventors, but 

 for common purposes it is only important that the orlSce be not too large, 

 and that the tube be provided with a reservoir for the reception of the 

 moisture which is carried into it with the breath. The flame of a neatly 

 tninmedlamp is undoubtedly the most convenient, but that of a common 

 candle is quite applicabk to the qualitative tests with which we shall 

 have occasion to deaL 



In looking at the flame of a candle, we may observe two principal 

 divisionsj which it is necessary by the assistance of the blowpipe to use 

 separately, since their action on the same substances is so different, as on 

 the one hand greatly to facilitate certain processes of analysis, and on 

 the other to cause much perplexity unless clearly understood. 



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The outer and larger part of the flame c, d, e, which is the source of 

 its light, is caused by the full combustion of the gases derived from the 

 oil, wax, or tallow which rises into the wick, and is called the reducing 



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