168 ACIDIFIABLE COMBUSTIBLES. 



into which it enters, the principal object of 



inquiry in this section will be into the atomic 



weight of silica. This inquiry is of great im- 



Proofs that portance ; because upon it the exact knowledge 



the atom of r 



silica or the constitution of most stony bodies depends. 

 I am of opinion that the atomic weight of silicon 

 is precisely 2, and I shall proceed to state the 

 evidence upon which that opinion is founded. 



*' In the y ear 1810j Berzelius published a 

 set of experiments, containing an analysis of 

 silica which he made in the following manner :* 

 He mixed together determinate proportions of 

 iron filings, silica, and charcoal in a crucible, 

 and exposed the mixture, properly covered, to 

 the greatest heat of a blast furnace. The united 

 action of the iron and charcoal decomposed the 

 silica, and the silicon as it was evolved, entered 

 into combination with the iron. The silicious 

 iron thus formed was whiter, and had a smaller 

 specific gravity than common iron. When dis- 

 solved in muriatic acid, it gave out a greater 

 proportion of hydrogen gas than common iron, 

 and this hydrogen gas contained a certain pro- 

 portion of carbon. It left undissolved a quan- 

 tity of silica. He dissolved a given weight of 

 this iron in muriatic acid, collected the hydro- 

 gen gas evolved, and by burning it over lime 

 water determined the quantity of carbonic acid 

 formed, from which he deduced the carbon 



* Afhandlingar. III. 117. 



