6 Prof. J. Joly on the 



Analysis 2. Chloanthite (cited as smaltite and numbered 19 

 in Table II. of paper in Phil. Mag. p. 861. June 1913). 



An analysis on the apophorometer gave the following 

 results : — 



Wt. taken 10*9 mgrms. This yielded 055 mgrm. arsenic 

 in group II., heating for 60 minutes at 255° ; and 6*51 mgrms. 

 arsenic oyer the interval 100° to white heat. The residue 

 showed but little cobalt and weighed 1*3 m grins. If its 

 composition be assumed to be NiO, the deficit on the added 

 weighings is 0*39 mgrm., which is accounted for by the 

 observed evolution of a little sulphur. The percentages are 

 As 64*2 ; Ni 31'7. The observations show that the more 

 stable molecule yielded 5*4 morms. As. Assigning the whole 

 of the Ni to it we get as its composition Ni 3 As 4 , very nearly. 

 The molecule breaking up in group II. is probably As 2 S 3 , and 

 the complete formula approximates to As 2 S 3 . 5 (Ni 3 As 4 ). 



Analysis 3. A partial re-analysis of the rammdsberqite~ 

 appearing in Table II. of the former paper as No. 15. 

 was made. 



T\'t. taken 10*6 mgrms. No sublimate was obtainable till 

 over 500° C. Between 500° and 700°, 7*6 mgrms. of As 2 3 

 were taken off. At a white heat a further 0*7 mgrm. was 

 evolved. These sublimates contain 6' 2 mgrms. As. The 

 residue seemed to be mainly NiO and weighed 5*3 mgrms.. 

 containing 4*25 mgrms. Ni. Total weight accounted for 

 10*44 ; deficit 0*16. From the result As 59*6 per cent. ; 

 Ni 41*3 per cent., the atomic ratios are As 79, Ni 69. If 

 (as is probable) Ni is a little over-estimated and we take the 

 ratio as 80 : 60 the formula Ni 3 As 4 is derived. The result 

 formerly arrived at and given loc. cit. p. 864, was As 58 per 

 cent., Ni 38 per cent., giving Ni 3 As 4 as above. The analyses, 

 therefore, agree. 



In the former paper RAs 3 was placed provisionally in 

 group II. There was then no direct experimental evidence 

 in support of this assumption. Recent observations on two 

 allomontites (SbAs 3 ) from Allemont showed that the evolu- 

 tion of As 2 3 began at 200° closely in both cases. This is 

 evidence in favour of the position assigned to the tri-arsenide 

 molecule. 



SuLPHCE. 



At a low temperature sulphur yields a sublimate of the 

 element which under the microscope is found to consist of 

 highly refracting globules. At higher temperatures it is 



