a new Mineral of Organic Origin. 469 



below after deduction of the mean percentage of ash, 8*14; 

 analysis V. after deduction of 8 per cent, of ash ; and analyses 

 VII. to XI. after deduction of 12*24 per cent, of ash. 



Carbon . 



79-34 



Hydrogen . . . 

 Sulphur . 

 Oxygen (by diff.) . 



10-41 

 5-32 

 4-93 



These numbers may fairly be taken as representing the cente- 

 simal composition of Tasmanite ; the most noteworthy point re- 

 garding them is the high percentage of sulphur. Tasmanite is, 

 I believe, the first carbonaceous mineral which has been found to 

 contain a large amount of sulphur in combination, not with a 

 metal as in pyritic coal, but in intimate union with the carbon 

 and hydrogen of the substance. It would seem to be allied to 

 retinite, although that mineral contains no sulphur; yet the 

 chief constituent of many specimens of retinite yields, on ana- 

 lysis, percentages of carbon and hydrogen almost exactly the 

 same as those just recorded. The formula C 10 H 16 O,orC 40 H 64 O 4 , 

 has been suggested for retinite. A similar formula, in which 

 sulphur is introduced, requires Dearly the same percentages as 

 those yielded in the analysis of Tasmanite : — 





Experiment. 



Theory, C 40 H 62 O 2 ,S. 



Carbon . . 



. 79-34 



79-21 



Hydrogen . 



. 10-41 



10-23 



Sulphur 



. 5-32 



5-28 



Oxygen . . 



. 4-93 



5-28 



100-00 100-00 



It will be seen that the experimental percentages of carbon and 

 hydrogen are a little higher than the theoretical : as one can 

 easily account for this excess in the case of a substance which is 

 hygroscopic and contains sulphur, I have been led to prefer the 

 suggested formula to one or two others which demand a higher 

 percentage of carbon and hydrogen. The sulphur determina- 

 tions are accordant ; but there is an apparent deficiency of oxygen 

 — 4'93 per cent, instead of 5*28. If, however, we accept the 

 theoretical percentages of carbon and hydrogen and the experi- 

 mental percentage of sulphur, we arrive, by difference, at the 

 following percentage of oxygen : — ■ 



Experiment. Theory, C 40 H 62 O 2 , S. 



Oxygen . ^ . 5 24 5*28 



Sulphur . . . 5-32 5'28 



If we accept the formulae C 40 H 64 O 4 and C 40 H 62 O 2 , S for 

 pure retinite and for Tasmanite respectively, we may compare 



