CARBON AND SILICON. 6l 



tion of a compound, we have several methods of studying the 

 character of the compounds of carbon, most important of 

 which are the determination of their molecular weights, boil- 

 ing and melting points. 



Like carbon, silicon forms a large number of compounds, 

 as any mineral collection will bear witness. Many minerals 

 of which silicon is a component occur in differing crystalline 

 forms, although their chemical composition is the same, indi- 

 cating a different molecular structure. The methods used to 

 identify different carbon compounds of the same percentage 

 composition cannot be applied in the case of these mineral 

 substances. As an example, molecular weights are mostly 

 determined by finding the vapor density of the substance. But 

 as we cannot get the silicon substance into the state of vapor, 

 this means is shut off. The methods depending on the raising 

 of the boiling point and the depression of the freezing point 

 are unsuitable, because any known liquid that will bring a 

 silicate rock into solution will also decompose it. 



Thus our knowledge of the isomeric silicon compounds 

 ends with the strong probability that they do exist in great 

 numbers, and that if we had at hand the means thoroughly 

 to investigate them, they would prove exceedingly interesting, 

 forming as they do a very large percentage of the earth's crust. 



In view of the wonderful discoveries continually being 

 made in chemistiy, it seems not beyond possibility that the 

 problem of the chemical structure of silicon compounds may 

 some day be solved. Neither w^ould it be surprising if some 

 one should succeed at last in producing the crystalline form 

 of the element silicon, and show us a jewel of rare beauty, 

 which may exceed the diamond itself in lustre and in hardness. 



