97 



Art. IX. PROGRESS OF FOREIGN SCIENCE. 



1. On Titanium and its Combinations with Oxygen and Sulphur, by 

 Henry Rose, of Berlin. 



In the first half of his paper, Mr. Rose treats of the peroxide of 

 titanium, (called by him, properly enough, titanic acid,) and its 

 combinations with the alkalis and acids. We do not find here any 

 thing very worthy of extract. After trying in vain to reduce that 

 oxide to the metallic state by zinc, and a stream of hydrogen gas 

 at high temperatures, he finally had recourse with happier effect 

 to sulphuret of carbon, employed in similar circumstances. 



The titanic acid should not be used in a pulverulent form, since 

 it is impossible to separate mechanically, the resulting sulphuret 

 of titanium from the residuary titanic acid. Hence he brought it 

 into the state of a thick paste with water, which he squeezed 

 strongly between folds of blotting paper under a press, so as to 

 obtain cohering pieces, which retained their cohesion on being ig- 

 nited. These lumps he put into a porcelain tube, to one end of 

 which a retort was luted air-tight, containing rectified sulphuret of 

 carbon. The other end of the tube terminated in a small glass 

 tube, which was left open. After the porcelain tube had been 

 heated red for half an hour, he applied a lamp to the retort, and 

 the gas was kindled as it issued from the end of the glass tube, in 

 order to shew, by the force of the flame, whether a suitable quantity 

 of sulphuret of carbon was evaporated. As the result was more 

 satisfactory in proportion to the slowness of the evaporation, he 

 reduced the flame to a size scarcely visible, by removing the lamp 

 to a considerable distance from the retort. The operation gene- 

 rally lasted from four to six hours, care being taken that some sul- 

 phuret of carbon should always remain in the retort. By means 

 of a spirit lamp, he then fused the extremity of the small glass 

 tube, and withdrew the apparatus from the fire, so that the sul- 

 phuret of titanium should be surrounded during the cooling with 

 an atmosphere of alcohol of sulphur, a precaution essential to pre- 

 vent the action of air on the ignited sulphuret, which would recon- 

 vert it into titanic acid. 



Sulphuret cf titanium, thus formed, has a dark green colour. 

 The slightest rubbing with a hard body, gives it instantly a strong 

 metallic lustre ; the metallic streak is brass yellow. When heated 

 in open vessels, it takes fire as soon as it becomes red hot, burn- 

 ing with a blue sulphureous flame, and is converted into titanic 

 acid. The metal of the compound gets oxygenated sooner than 

 the sulphur, by roasting in the air. On pouring nitric acid on the 

 sulphuret, nitrous vapours exhale, the mixture becomes hot, and 

 finely comminuted titanic acid falls to the bottom of the vessel. 

 The simplest and most accurate method of analyzing this sul- 

 phuret, was by its combustion, on platinum foil over a spirit lamp, 

 in this way, hard fragments were obtained, which on the slightest 



Vol. XVI. II 



