118 M, Berzelius on Silicium. [Aug. 



much deeper. Being now washed and dried, it constituted sili- 

 cium in a state of purity. 



Silicium obtained in this manner has a dark nut-brown colour, 

 and is wholly destitute of metallic lustre. When rubbed upon 

 a polishing stone, it does not communicate a shining streak. It 

 is incombustible both in atmospheric air and in oxygen gas ; and 

 it appears to be highly infusible, for it undergoes no change in 

 the flame of the blowpipe. This circumstance appears contra- 

 dictory of what I have already stated respecting the easy com- 

 bustibility of the silicium which is obtained immediately after 

 its reduction by potassium. The difference between its proper- 

 ties in these two states is indeed highly remarkable ; and I have 

 fully ascertained that it is not occasioned, on the one hand, by 

 the adherence of potassium, or, on the other, by the subsequent 

 digestion in fluoric acid. Most probably, the combustibility of 

 the silicium proceeds from its being combined with a small 

 (quantity of hydrogen, for if it be burned in oxygen gas, even 

 after having been ignited in an atmosphere of hydrogen gas or 

 in vacuo, there is invariably formed a certain quantity of water, 

 although its amount indeed is inconsiderable when compared 

 with the high saturating capacity of silicium. The sihcium 

 obtained by treating the reduced brown-coloured mass with 

 water is therefore a hydruret. The reduced mass is originally a 

 siliciuret of potassium, which is decomposed by the water ; the 

 potassium converted into potash, passes into solution ; the 

 greater part of the hydrogen separates in the state of gas, and a 

 smaller portion enters into combination with the silicium. In 

 the incoherent condition in which it is separated from potassium 

 by the action of water, silicium may be compared to the loose 

 tinder (a hydruretted carbon) ])repared from linen, which may 

 be easily kindled by a spark from steel ; but after having been 

 exposed to an elevated temperature, it may be compared to coke, 

 which is, by itself, quite incombustible. 



Silicium has an extreme tendency to soil even when in a state 

 of dryness, and it adheres strongly to the glass vessel in which 

 it is kept. It is a non-conductor of electricity. 



The incombustible silicium is not altered by ignition with 

 chlorate of potash. In nitre it does not deflagrate until the tem- 

 perature has been raised so high that the acid undergoes decom- 

 position, when the affinity of the disengaged alkali co-operates 

 with that of the oxygen. In carbonate of potash it is oxidized 

 with great readiness, and with intense ignition ; carbonic oxide 

 is at the same time disengaged, and the mass assumes a black 

 colour in consequence of the reduced carbon. This property 

 gives occasion to a very paradoxical phaenomenon. If the 

 incombustible silicium be moderately heated with nitre, no 

 action ensues between the two substances ; but if a bit of anhy- 

 drous carbonate of soda be now introduced, the silicium at the 



