238 DR BROWN ON THE PRODUCTION OF SILICON FROM PARACYANOGEN. 



and those charred products of the ferroprussiates which will be investigated in 

 another section ; and especially by BOUSSINGAULT'S own observation that the reac- 

 tion of carbon, yielding no silica on combustion, produced no siliciuret, for such 

 carbon must have been truly mineral, and not exorganic like charcoal. 



III. On the quantity of Nitrogen separated from Paracyanogen tvken it is changed 



by heat into Nitrogen and Silicon. 



It has been already implied that the quantity of silicon obtained from paracy- 

 anogen corresponds with that of the carbon known to exist in this compound. 

 The accidental observations of the foregoing section suggested the following me- 

 thod of determining that during the transformative process the whole of the 

 nitrogen is given off as such. 



1. Five grains of paracyanogen, prepared with extreme care, were mixed with 

 little shreds of fine platinum foil, weighing twice as much as would have sufficed to 

 absorb all the silicon which could be extracted from the paracyanogen employed. 

 The weighings and mixture having been made in a glass-tube, closed at one end, 

 the open extremity was drawn out just above the contents, and bent over. A 

 spirit-flame was applied to every part of the containing tube in succession, and 

 the separated gases collected over mercury. Without interval it was raised to a 

 full red heat by means of the spirit-blast lamp,* and this temperature was kept 

 up as long as any thing was given off. After the operation, the little retort was 

 found to contain nothing but the siliciuretted platinum described in II. 3. As 

 for the gaseous products, it may be observed that as much of the air of the appa- 

 ratus as possible was expelled before the application of the spirit-lamp and the 

 collection of the products ; and, being altogether certainly not more than 0.01 gr. as 

 well as partly balanced by the attenuated nitrogen which could not be driven out of 

 the tube at the close of the operation, it could not introduce any error worthy of ob- 

 servation in an analysis of this kind. The whole product was 8.9 cubic inches at 60 C 

 Fahr. and 30 bar. Potassa removed C. I. 3.8 of cyanogen, or 2.1 grs., and shewed 

 that the original 5 grs. was equivalent to only 2.9 grs. of true paracyanogen. 

 There thus remained C. I. 5.1 or 1.56 gr. of nitrogen, produced from 2.9 grs. of pa- 

 racyanogen, the calculations from measures to weights being made on the data of 

 GAY-LUSSAC, and the due corrections according to rule. 



2. Fifteen grains of the same parcel were ignited in a clean little platinum cru- 

 cible, from which the air was carefully excluded. The loss sustained was 10.59 grs., 



* The convenient little furnace, here referred to, is described and figured in Dr COKMACK'S Monthly 

 Journal of Medical Science for March 1841. 



