292 M. Hertzberg*s Observations on the 



with small crystals of heavy-spar of the same kind as that 

 which replaces the crystals of witherite. 



VIII. Changes in Minerals containing Antimony. 

 The chemical changes of the minerals containing antimony 

 have not been sufficiently attended to. It is certain that the 

 native antimony takes up oxygen, and then presents a white 

 opaque mass, showing every peculiarity, in respect of form, of 

 the original substance, as I have seen in a specimen in the mu- 

 seum at York. This is probably the oxide of antimony. The 

 prismatoidal antimony-glance consists of sulphuret of anti- 

 mony, a mixture of one atom of the metal and three atoms of 

 sulphur, Sb S 5 , the ratio of antimony and sulphur being 72.77 

 and 27.23. It is converted by decomposition into a yellow- 

 ish opaque mass, of an earthy aspect, which is proved by ex- 

 periments with the blowpipe still to contain a notable quantity 

 of sulphur, beside water and antimony. In this case the form 

 is preserved. Sometimes, however, as at Braunsdorf in 

 Saxony, the decomposition is complete, and attended with 

 change of form, in the same manner as the lead-glance. The 

 decomposition begins from the surface, which is corroded, and 

 becomes perfectly smooth. In the cavities thus produced, 

 crystals of the antimony-baryte are deposited, which consist 

 of pure oxide of antimony, one atom of the metal combined 

 with three atoms of oxygen, or Sb, the two ingredients being 

 in the ratio of 84.32 to 15.68. Each atom of sulphur is ex- 

 actly replaced by an atom of oxygen. 



(To be concluded in next Number.) 



Art. XIV. — Observations on the Barometer and Thermome- 

 ter made at Malmanger and Ullensvang in Norway, during 

 a period of' thirty years, from 1798 to 1828. By Provost 

 Hertzberg of Ullensvang. Communicated by the Author. 



In the Thirteenth Number of this Journal we have already 

 published a table of the minimum and maximum height of the 

 barometer, deduced from twenty-nine years' observations, by 

 M. Hertzberg, Provost of Hardunger, and pastor of Kings- 



