1824.] Chemical Composition of Red Silver Ore. 31 



generated by dissolving granulated zinc in dilute sulphuric acid. 

 All the different pieces of the apparatus were carefully weighed 

 in the first place to enable me to determine what might be driven 

 off, or what addition might be made to the substances operated, 

 on during the process. 



Experiments with a Mixture of Sulphuret of Antimony and 



Oxide of Antimony. 



Antimonious acid prepared from subantimonite of potash 

 (crocus antimonii elota) by digestion in nitric acid, was. mixed by 

 trituration with its own weight of metallic antimony in fine pow- 

 der, and put into a glass globular vessel blown by the lamp,, 

 having a capacity of fully a cubic inch, the mouth of which was 

 afterwards drawn out into a capillary tube. This glass vessel 

 was put into a crucible, and was raised to a red heat, which was 

 kept up about ten minutes. When the glass was broken in 

 pieces, there was found in its upper part white or yellowish-white 

 crystals, of two different forms ; namely, octahedrons and pris- 

 matic needles. The mass found at the bottom consisted of a 

 metalline regulus lying undermost, and over it an oxide consist- 

 ing of a fused yellow-grey mass, having a crystallized fracture, 

 and containing drusy cavities, lined with white, short, needle- 

 shaped crystals. Sulphuret of antimony was prepared from this; 

 regulus by mixing it with 40 per cent, of pure native sulphur, andi 

 heating it in a little glass globular vessel. It was crystallized,, 

 and all excess of sulphur had been driven off by heat. 



The purest portions of the oxide thus obtained were pulve- 

 rised, and exactly mixed with the sulphuret of antimony, accord- 

 ing to the proportions which Berzelius has given for the consti^ 

 tution of red ore of antimony (Rothspeissglanserz), S/> + 2 S& 

 S J ; namely, 100 parts sulphuret with 43*2 parts of oxide.. A 

 quantity of this mixture was put into a glass globe blown by the 

 lamp. This quantity after being gently heated weighed 2-335 

 grammes. The glass was exposed to the flame of a spirit-lamp, 

 and as soon as the mixture became fully red-hot, it melted, and 

 was found after cooling still to weigh exactly 2'335 grammes.. 

 The product of this operation was a glass having the metallic 

 lustre and a dark steel-grey colour with a shade of red, very 

 similar to the dark variety of red ore of antimony. It appeared" 

 opaque, except those portions which had formed a thin crust on 

 the inside of the glass. These were translucent, and had a yel- 

 lowish-red colour. When reduced to powder, it had a dark 

 reddish-brown colour. As the weight was not altered by the 

 fusion, it is obvious that it had lost no sulphur nor oxygen dur- 

 ing the process. 



A portion of the powder of this crocus, or compound of sul- 

 phuret and oxide of antimony, was put into the part of the 

 apparatus marked E, which, after being gently heated, weighed' 



