THEIR HISTORY. 97 



pipe, with its charcoal and diamonds intact. The result of this 

 experiment proved that, while the Diamond disappeared when 

 subjected to a great heat in the presence of air, it resisted the 

 utmost heat that could be applied if air was completely excluded. 

 Once this fact was established, the final solution of the problem of 

 the analysis of the Diamond could not long be delayed, and soon 

 Lavoisier in France, and Sir Humphrey Davy in England, answered, 

 each in his way, the question of "What is the Diamond?" 

 Lavoisier succeeded in burning a diamond in an atmosphere of 

 oxygen over mercury by means of a burning lens^ and established 

 by the presence of carbonic acid after the combustion, that car- 

 bon was one of the elements of the Diamond. Davy went still 

 further, and showed that as the combustion of a diamond in an 

 atmosphere of oxygen gave rise to nothing else than carbonic acid 

 or carbonic oxide, th$ Diamond consisted simply of carbon in a 

 state of absolute purity. In fact, it was that element crystalHsed, 

 and the Diamond had at length yielded to the chemist the secret 

 of its nature, as its form and hardness had yielded to the patience 

 of the lapidary. The Diamond was conquered and much of the 

 mystery enveloping it dispelled, but there yet remained to be dis- 

 covered its origin and true geological position. Before, however, 

 entering upon this question, it will be well to consider carefully the 

 Diamond as a mineral, and to make ourselves acquainted with its 

 form and characteristics. 



The Diamond belongs to the tesseral or cubic system, having 

 three axes at right angles, and occurs in many different forms and 

 appearances. So dissimilar, indeed, are some specimens from the 

 normal type, that the uninitiated would hardly suppose they could 

 be the same substance. It is found as crystals of various shapes 

 and of every colour, also in more or less crj^stalline masses of no 

 special or definite form. This variety is known as Bort, and is of 

 no use as a gem, being so flawed and knotted in its formation as to 

 be almost, or quite, opaque. It has, however, its value, being of 

 great importance in the arts and for mechanical purposes. Be- 

 sides the crystalHsed forms, there is an exceedingly curious and 

 interesting variety, almost amorphous, that is called Carbonate, 

 occurring in broken pieces, opaque, black, reddish, or grey, and 

 very rarely showing traces of crystalline structure. In appearance 



