﻿90 . Canadian Record of Science. 



under the name of Carborudum. The powdered crystals 

 have sharp cutting edges, hard enough to scratch rubies, 

 and consequently make an excellent polishing and grind- 

 ing material. 



It is to be noticed that this formation of carbides 

 affects the elements which make up by far the larger part 

 of the earth's crust, so that from a geological as well as 

 a chemical point of view these newly discovered trans- 

 formations are of the utmost importance. 



The reduction of these oxides to carbides is only possi- 

 ble at the high temperature of the electric furnace, and it 

 is very interesting to note that at three very different 

 stages of temperature we have such different conditions 

 presiding over the union of the elements that each tem- 

 perature corresponds to a new chemistry. 



The temperature of the electric furnace, which has 

 been estimated to be from 3,500° to 4,000° Cent, may be 

 considered as intermediate between the sun's temperature, 

 estimated by different physicists at 5,000° to 8,000°, and 

 the temperatures of our smelting furnaces, which range 

 from 1,200° to 1,500°. Now, in the sun's atmosphere, 

 spectroscopic observations tell us that the elements exist 

 uncombined, and we can even observe great masses of free 

 oxygen in the presence of heated hydrogen and of metals 

 so transformed in the properties which we are accustomed 

 to recognize that they do not combine, but rise as vapours 

 from the hottest part of the sun, condense and fall back 

 in metallic clouds, which w^e know as sun spots. Here, 

 then, is a temperature which is too hot for chemistry, if 

 we define chemistry as the science of the combination of 

 bodies. 



The next temperature on a descending scale that we 

 have access to is that of the electric furnace ; here a par- 

 tial combination only is possible ; much of the oxygen 

 remains free ; carbon only burns to the monoxide of 



