834 SIB B. C. BKODIE ON THE CALCULUS OF CHEMICAL 0PEEATI0N8. 



and 



whence 



Zm2=ZiW2, 



which give 



m =2, n =0, 

 my=.ii, ni=0, 



a minimum, whatever be the values of z and z^, if only z and Zj be positive and integral. 

 This gives as the symbol of chloride of silicon a^^V', and the symbol of silicon a'; and 

 assuming 85 as the density of the chloride of silicon, 



2+4xl7-25+Zi«;(ff)=85, 

 and 



, , 14 



Again, in the decomposition of silicon-ethyl it has been experimentally ascertained 

 that putting Zg as the number of volumes of silicon-ethyl decomposed, and Zg, Z4, Zj as 

 the number of volumes of hydrogen, carbon, and silicon respectively formed by its 

 decomposition, 



13^10, ^*=^, and ^«=^, 

 where - is the ratio of the number of volumes of carbon formed to the number of 



y 



volumes of marsh-gas decomposed, in the equation expressing the result of the decom- 

 position of that substance (Sec. VII. Group 2 (1)), and z and z-^ have the values assigned 

 to them in the previous equation. Hence, putting a"';^"''(r'^ as the symbol of silicon-ethyl, 

 X? as the symbol of carbon, and (f as the symbol of silicon, and substituting the above 

 values for z^, Zj, z^, z^ in the equation 



Z2a"'x."''a^=z^u+ZiX''-\-z^a', 

 we have 



yz X a'"«'"'ff'^=10yz X a+8a-z X x'+yZi X (r't 

 whence 



and 



m=10, m^^x, W2=Zi; 



and we have for the symbol of silicon-ethyl, as determined from experiment, a'^x^ff*', or, 

 putting a^=l (Sec. VII. Group 2 (1)), as in the symbols of the other compoimds of 

 carbon, a'°xV', 



Proceeding in a similar manner with the other gaseous compounds of silicon, we have 



