Pro!:. J. Joly on the Apophorometer. 307 



u more normal specimen, one was chosen which gave the 

 -characteristic cobalt bead with borax. 



Smaltite highly cobaltiferous. Weight taken 1-4*7 mgrms. 

 As in the case of the other smaltites there was some de- 

 flagration at very low red heat and a copious sublimate 

 collected. This white sublimate weighed 1,3*2 mgrms. and 

 ■contained 10*1 mgrms. of As. The weight of the residue, 

 which was a very dark ash-red colour, was 7*2 mgrms. 

 If this is C03O4 it contains 5*4 mgrms. of Co. The added 

 weights amount to 15*4 mgrms. and the As found was just 

 70 per cent, of the weight dealt with, and therefore agrees 

 with the formula. 



Molybdenite. MoS 2 . S 40 ; Mo 60. Weight takenSO'S mgrms. 



Having found by trial that only S0 2 was evolved at a low 

 red heat, the substance was roasted with the upper glass 

 removed. A crystalline residue of M0S3 remained on the 

 ribbon. This was swept off and weighed: =19*1 mgrms. 

 Hence Mo = 12*7 and tS = 8*l by difference. The formula 

 gives Mo 12*5; S 8*3. 



Argentite. Ag 2 S. Ag87*J ; S 12*9. Weight taken 14*lmgrms. 



At a cherry-red heat S0 2 escaped and Ag was left. This 

 was swept into the lower glass and any still adhering silver 

 sublimed off the ribbon. Weight of Ag = .12*4 and, by 

 difference, S = l*7. On the formula Ag = 12*3 ; S = l*8. 



These few initial results will be sufficient to illustrate the 

 applications and uses of the apophorometer. I do not think 

 there is any doubt that for rapid determination of mineral 

 species it will be found of use. Percentage estimates as 

 •cited above would take many hours to obtain by the ordinary 

 processes of chemical analysis. A good result can easily be 

 obtained in an hour by the apophorometer and on a very 

 few milligrams of material. A very large number of mineral 

 species may be partially analysed by its means and, by 

 weighing and qualitatively testing the residue, complete 

 analyses can, in many cases, be obtained, to a degree of 

 accuracy sufficient for determining the species or investigating 

 new ones. 



But it will, I think, be found that something more than 

 the discrimination of substances, mineral or other, may be 

 accomplished with it. We can by its means determine the 

 relative stabilities of the constituents of many volatile com- 

 pounds at high temperatures. It is not improbable that 

 light will in this way be thrown on the internal constitution 



