78^700 





78 gr *700 



99°*49 





99°*49 



22°-01 





22°*70 



2°*2739 





2°-2986 



464s r -48 





464s r -48 



01732 





0-1767 





0-1' 



^50 



120 Prof. Regnault on the Specific Heat of some Simple Bodies. 



At my request M. Caron was good enough to melt this into a 

 single regulus. 1 then obtained the following results : — 



M . . . 



T . . . 



6' . . . 



A0' . . . 



A . . . 



C . . . 



Mean 



The experiments made with the silicon melted by M. Caron 

 are evidently the most reliable, because they were made with a 

 sufficient quantity of substance. They lead to the result that 

 the specific heat of silicon is 0*1750, which is virtually the same 

 as that of crystallized silicon (p. 119). 



The mean specific heat, 0*176, multiplied 



by the atomic weight, 266*7, gives the product 46*92 



1778 v „ 31*29 



88*9 „ 15*64 



None of these results is comprised within the limits of varia- 

 tion which we have found in the case of other bodies. We must 

 assume either that silicic acid has none of the formula? which 

 chemists have hitherto assigned to it, or that crystallized silicon 

 is not a simple body, but contains another element which has 

 escaped the sagacity of observers, or, lastly, that silicon forms an 

 exception to the law of the specific heats of simple bodies. It is 

 difficult to admit that this anomaly arises from a numerical error 

 in the determination of the equivalent of silicon ; for this equi- 

 valent has been determined by the synthesis of silicic acid, and by 

 the analysis of chloride of silicon. 



In order that silicon should obey the law of the specific heats 

 of simple bodies with the value which we have found for its 

 specific heat, it would be necessary to write the formula of silicic 

 acid, Si 2 5 ; it would then resemble that of nitric, phosphoric, 

 and arsenic acids. The atomic weight of silicon would be 222*3, 

 and the product of this atomic weight by its specific heat would 

 become 39-12, which agrees with the analogous product which 

 the other simple bodies give. 



If we are only guided by apparent analogies, it is not difficult 

 to find resemblances between silicon, phosphorus, and arsenic. 

 Thus :— 



Silicic acid being a polybasic acid, could form, like phos- 

 phoric and arsenic acids three kinds of salts, — monobasic, bibasic, 

 and tribasic; it would thus be easier to explain the great number 

 of silicates with multiple bases which nature offers us in beau- 



