134 ON STIBICONI3E, A NATURAL OXIDE OF ANTIMONY FROM BORNEO. 



Mineralogists are not agreed npon the quantity of combined water 

 contained in Stibiconise, but the analyses I have made of the Borneo 

 mineral appears to leave no doubt as to that question. The following 

 record of one of the best analyses will show in what ratio the water stands 

 to the antimonious acid : — 



Stibiconise from Borneo. 



Oxygen. Ratio. 



Water 3-75 3-33 1 



Antimonious acid, Sb 65'00 12-30 4 



Oxide of Iron 



I 



Sulphur, silica, &c 21 - 25 



Alumina 



10000 



From this we may, therefore, deduce as the formula of Stibiconise : — 

 Sb O 4 , H 0. 



The specific gravity of Stibiconise, according to several authors, is 3 - 80 ; 

 but all the samples of the Borneo mineral gave me densities, varying from 

 4-64 to 4'68, whence I concluded they woidd probably contain silver. 

 However, I could not find in them sufficient silver to account for this in- 

 crease of specific gravity. Neither does the Borneo Stibiconise show more 

 than a trace of arsenic. 



As the Stibiconise (antimonious acid) of which I speak, accompanies 

 Stibine (sulphide of antimony) in Nature, and affects the same crystalline 

 form as the latter, it is very probable that the oxide in cpiestion has been 

 formed in Nature at the expense of the sulpiride, by means of water or 

 steam heated under pressure, as we see it act in the beautiful experiments 

 recently made by my friend, M. Daubree, where Wollastonite, and some 

 other minerals, were artificially formed in perfect crystals by the mere 

 action of superheated steam upon glass in closed tubes. The chemical 

 reaction which Nature appears to have used in forming Stibiconise from 

 Stibine is as follows : — 



SbS 3 + 3 HO = SbO 3 + 3SH. 

 Stibine. Water. Oxide of anty. Sulph. hyd.; 

 and Sb O 3 combining with one proportion of oxygen from the air gives 

 Sb O * antimonious acid or Stibiconise. 



If we suppose, for a moment, that the transformation in question was 

 effected by air (oxygen), instead of water, we find that it would require nine 

 equivalents of oxygen to produce the same effects as three equivalents 

 of water : — 



SbS 3 + 90 = Sb0 3 + 3S0 2 



Stibiconise has been regarded as a somewhat rare mineral in Europe, 

 but Borneo seems to possess large quantities of it. Another argument in 

 favour of its formation from Stibine is, that it always accompanies the 

 latter in Nature. 



The Stibiconise of Borneo is readily dissolved in a warm mixture of 

 hydrochloric acid and tartaric acid. To transform it into metallic antimony, 



