148 Miscellaneous Intelligence. 



termination of the composition and nature of certain sulphuiets, 

 such as those of the alkaline and earthy metals. " They have," 

 says M. Berthier, " given me the means of resolving the 

 question, till now undecided, whether the alkalies and alkaline 

 earths are or are not in the metallic state in the sulphurets pre- 

 pared by fire. They are so simple, that one is astonished they 

 have not been made before ; and it may be seen they conduct, 

 in the most evident and direct manner, to the knowledge of the 

 nature of the alkalies and alkaline earths." 



The method by which M. Berthier reduces sulphates to sul- 

 phurets is not by directly mixing them with powdered charcoal, 

 and heating them in a crucible, but by placing them in the 

 centre of a crucible, thickly lined with charcoal, covering them 

 •with the same substance, and after having luted on a cover, 

 heating the whole in a furnace. In this way the sulphates are 

 reduced by cementation, as it were, the time required being 

 proportioned to the temperature, the fusibility of the sulphurets, 

 and the volume of the substance. All are reducible at a white 

 heat, and, where the sulphuret is fusible, very quickly ; but 

 when it is infusible, it lemains interposed between the charcoal 

 and the sulphate, and the action is slowei*. An ounce of sul- 

 phate may in this case require above two hours. In this way not 

 only are pure sulphurets obtained, but the result may be col- 

 lected without the smallest loss, its weight ascertained, and the 

 weight of oxygen evolved accurately estimated. 



If a sulphate of baryta, strontia, or lime, be thus reduced to 

 a sulphuret, and weighed, the loss will be found to equal ex- 

 actly the quantity of oxygen contained in the base and acid. 

 If the sulphuret be dissolved in muriatic acid, nothing will be 

 liberated but pure sulphuretted hydrogen ; no sulphur will be 

 set free, nor any acid, containing sulphur and oxygen, formed ; 

 finally, if a portion of the sulphuret be heated in a crucible of 

 silver, with nitre equal to three or four times its weight, the sul- 

 phate regenerated will correspond with the quantity of sulphu- 

 ret employed, and will contain neither acid nor base in excess. 

 These three experiments prove that the sulphuret produced 

 contains no oxygen, and, consequently, that the base is in the 

 metallic state ; and if, in addition to these means of analysis, 

 the experiment be made in close vessels, and the gaseous pro- 

 ducts collected and analyzed, it will be found that the loss of 

 weight sustained by the sulphate is exactly made up by the 

 quantity of oxygen given off. 



