1822.] Method of analyzing the Ores of Nickel. '445 



called grey nickel, to indicate that its composition is analogous 

 to that of grey cobalt. 



It is evident, that the quantity of arsenic found in the mineral 

 is too small to form a biarseniuret with the whole of the nickel ; 

 and the variable quantity of iron indicates that the sulphuret 

 of this metal, or its arsenio-sulphuret, is mixed with it, and not 

 combined in definite proportion, either with the arseniuret of 

 nickel, or the arsenio-sulphuret. 



IV. Detailed Account of the Method of analyzing the Arseniurets, 

 or the Arsenio-sulphurets of Nickel and Cobalt, by Means of 

 Chlorine Gas. 



It has been seen, by what has been stated, that arsenic and 

 other metals were completely separated, only by the decom- 

 position effected by means of chlorine gas ; and notwithstand- 

 ing each of the other methods has given an approximation to 

 the true composition, they cannot be regarded as good ; for 

 every experiment which leaves the operator in doubt, must be 

 considered as inconclusive, unless it be confirmed by an- 

 other less questionable process ; but then it is better imme- 

 diately to employ the most certain method. 



I am, therefore, now going to relate more particularly the 

 method of analyzing nickel ores by chlorine gas, and I shall 

 notice the precautions which are requisite to obtain the object. 



At three inches from one of the ends of a barometer tube, 

 blow a bulb of such a size that it shall be only one-third filled 

 with the powder of the substance to be examined. On the other 



