134 D. Forbes, Esq., on the Determination of 



quite accurate results ; but the heat required was found in- 

 conveniently great, and considerable difficulty was found in 

 decomposing the last traces of sulphate ; in consequence, 

 therefore, the method now about to be noticed was tried and 

 found much more convenient in practice, and to afford very 

 accurate results. 



Upon analysing the residue left after incinerating the 

 sulphurets produced by precipitating these metals, it was 

 found to consist of a mixture of the disulphuret and oxide 

 of the metal, and containing a small amount of sulphate ; — 

 this will be seen from the following results : — 

 (a) 13*27 gr incinerated sulphuret of nickel (precipitated by 



hydrosulphuret of amnion 



Nickel, 

 Sulphur, 

 Oxygen, 

 Sulphuric acid, 



um), yielded on analysis, 



10-35 

 0-60 

 2-21 

 0-11 



13-27 

 which by calculation will be equivalent to- 

 Nickel, . . . 2-21 



Sulphur, • . . 0-60 



Nickel, . . . 8-08 



Oxygen, . . . 220 



Oxide of nickel, . . 0-09 



Sulphuric acid, . . 0*1 1 



2-81 Ni 2 S 



10-28 NiO 



0-20 NiOSO, 



13-29 

 which shews a difference of only 0*02 gr. from the ob- 

 tained results. Again, in case of copper, 

 (/>) 2*24 gr. incinerated sulphuret of copper (precipitated by 



a stream of sulphuretted 



Copper, 

 Sulphur, 

 Oxygen, 

 Sulphuric acid, 



ydrogen), afforded- 



1-760 

 0-058 

 0-392 

 0030 



2-240 



