Chemistry. 177 



ed, it is important to subject the compound to some operation by which 

 the metal may be obtained in a separate state. Professor Orfila, in his 

 work on Toxicology, (vol. i. p. 465, third edition,) states, that the pre- 

 cipitate in question, '' dried on a filter, and mixed with charcoal and the 

 potash of commerce, gives a button of metallic antimony by the action of 

 heat. This reduction of the oxide of antimony by charcoal may be made 

 in an earthen crucible, and is completed in the space of about ten or tyvelve 

 minutes." It is chiefly to this part of the process for detecting antimony 

 that I have found reason to object. I do not, indeed, deny that the pro- 

 cess will succeed perfectly, when a considerable quantity of the materials 

 is employetl ; but in operating on such quantities as are likely to be met 

 with in medico-legal investigations, my attempts to procure the metal in 

 this way have proved completely fruitless. Thus, four grains of the sul- 

 phuret, precipitated from tartar emetic by sulphuretted hydrogen, and 

 well dried, were mixed with an equal weight of charcoal and dry carbonate 

 of potash. The mixture, protected on all sides by charcoal, was placed in 

 a Hessian crucible, carefully luted, and was then exposed to heat during 

 fifteen minutes. The experiment was twice repeated ; and on one occasion 

 a full red, and on the other a commencing white heat was employed, but 

 in neither case could I perceive any trace of the metal. On examining the 

 residue chemically, I found that some particles of metallic antimony were 

 diffused through the mass, though they could not be discovered by the 

 eye ; while another portion still remained as sulphuret, and was dissolved 

 by the potash on the addition of water.* These experiments were varied 

 by mixing the sulphuret with black flux, and heating the mixture in a 

 glass tube by means of a spirit lamp ; but a metallic globule was not pro- 

 cured, though the heat was augmented by aid of the blowpipe. It is 

 worthy of remark, that in none of these trials was there any appearance of 

 a metallic subli^nate; so that, were colour insufficient for distinguishing 

 orpiment from the sulphuret of antimony, the black flux would afford an 

 easy mode of distinction. 



Having failed in my attempts to procure the metal by the preceding 

 process, I had recourse to another whicli proved successful. It is founded 

 on the property hydrogen is known to possess, of separating sulphur from 

 antimony at an elevated temperature, — a property, of which advantage 

 has been taken for the purposes of analysis. In performing this operation, 

 the dry sulphuret is placed in the middle of a glass tube about three inches 

 long, and a quarter of an inch in diameter. One end of the tube is con- 

 nected by means of a cork with a vessel, from which hydrogen gas is 

 evolved ; and to its other extremity is adapted a bent tube, which opens 

 under water, so as to conduct away the hydrogen, and at the same time ex- 

 clude atmospheric air. After the air within the apparatus has been expel- 

 led, heat is applied by means of a spirit lamp to the part of the tube on which 

 the sulphuret is placed. The decomposition of the sulphuret commences 



• This, we apprehend, is owing to the formation of a double sulphuret of anti- 

 mony and potassium — E. T. 



VOL. VIII. NO. I. JAN. 1828. M 



