Action of Nitric Acid and Charcoal. 393 



so concentrated, that during evaporation it thickens, coagu- 

 lates, and deposits portions of the earth, in the form of gummy 

 transparent masses. The siliciuret of potassium, heated with 

 sulphur, burns vividly, and when dissolved, leaves the pure si- 

 licium. Silicium takes fire in chlorine at a red heat, and a 

 liquid results, colourless, or of a light-yellow colour, of an 

 odour resembling that of cyanogen, very* volatile, and which, 

 with water, congeals and deposits gelatinous silica. I have 

 not as yet examined its conducting power for electricity and 

 heat, its specific gravity, &c. 



Nothing is easier than to procure this substance ; the fol- 

 lowing is the mode I have ultimately adopted : The double 

 fluate of silica with potash or soda, heated almost to redness 

 to drive ofFhygrometric water, is introduced into a glass tube, 

 closed at one extremity ; pieces of potassium are then to be 

 introduced, and the metal carefully mixed with the powder, 

 by heating it till it fuses, and then lightly striking the tube. 

 It is then to be further heated by a lamp; and before it attains 

 a red heat there is a slight detonation, and the silicium is re- 

 duced. The mass is to be cooled, and then washed with wa- 

 ter as long as any thing dissolves. There is at first disengage- 

 ment of hydrogen gas, because a portion of siliciuret of potas- 

 sium has been formed, which cannot exist in contact with wa- 

 ter. The washed substance is a hydruret of silicium, which at 

 a red heat burns vividly in oxygen gas, although the silicium 

 is not completely oxidized ; it is to be heated in a covered 

 platinum crucible, slowly augmenting the fire to redness ; the 

 hydrogen only oxidizes, and the silicium will no longer burn 

 in oxygen gas, though chlorine attacks it very easily. The 

 little silica produced may be removed by fluoric acid; but if 

 the silicium has not been strongly heated, the acid will dissolve 

 a little of it, with the disengagement of hydrogen. According 

 to the synthetical experiments which I have made, silica con- 

 tains about 0-52 of its weight of oxygen. 



Zirconium is obtained in an analogous manner. It is as 

 black as carbon, does not oxidate in water or in muriatic acid, 

 but nitro-muriatic and fluoric acids dissolve it, the last with 

 the disengagement of hydrogen. At a temperature but slightly 

 elevated it burns with great intensity. It combines with sul- 

 phur. In sulphuret is of a chesnut-brown colour like silicium, 

 and insoluble in muriatic acid or the alkalies. It burns with 

 brilliancy, producing sulphurous acid <ras and zirconia. — Ann, 

 d< ('him. xxvi. H. 



ACTION OF HITRIC ACID AND CHARCOAL. 



Professor Silliman formerly pointed out the production of 

 Vol. 64. No. 319. 2Vbr. 1821." 3D hydrocyanic 



