ALLOTROPIC CONDITIONS OF ATOMS. 43 



We are, however, convinced by experiment that the 

 brilliant and transparent gem is made up of the same 

 atoms as those which go to form the dull black mass of 

 charcoal. From diamonds, as is above stated, coke has 

 been formed by the heat of the voltaic battery, and re- 

 cent experiments have proved that the volatilized 

 carbon constantly passing off from one of the poles of a 

 sufficiently powerful battery, is deposited in a crystal- 

 line powder, possessing most of the properties, as it 

 regards hardness, &c. of true diamond dust. What is 

 the mystery of this? We know not. The peculiar 

 conditions have been the subjects of anxious study ; but 

 science has not yet let in a ray of light upon the 

 mystery. That a different state it has been called 

 an allotropic condition is often induced in the same 

 class of atoms is certain ; and hence the variety of the 

 resulting compounds. To continue our illustrations 

 with carbon may not its combinations, in uniform pro- 

 portions with oxygen and hydrogen,* owe their differ- 

 ences to some allotropic change in the ultimate atoms of 

 this element. 



We know that silicon the metallic base of flint is 



* " In the annua report on the progress of chemistry, presented 

 to the Royal Academy of Stockholm, in March 1840, I have 

 proposed to designate by the term allotropic state, that dissimilar 

 condition which is observed in certain elements, and long known 

 examples of which are found in the different forms of carbon, as 

 graphite and diamond. 



" Although these dissimilar conditions, which I have here called 

 allotropic, have long since attracted attention in one or two 

 elements, still they have been regarded as exceptions to the 

 general rule. It is at present my object to show that they are 

 not so rare ; that it is probably rather a general property of the 

 elements to appear in different allotropic conditions ; and that 

 although we have hitherto been unable to obtain several of the 

 elements when uncombined in their allotropic states, still their 

 compounds indicate the same with tolerable distinctness." Ber- 

 .zeliiis on (he Allotropy of the Elementary Bodies, fyc. : Poggen- 

 dorff's Annalen, 1844. Scientific Memoirs, vol. iv. p. 240. 



