302 



the oxygen of the air, so that by a slow process of spontaneous de- 

 composition, and gradual oxidation or eremacausis, all the consti- 

 tuents of the anthracite, except the excess of carbon and the ash, 

 may be evolved, and carbon left free. 



The separation, in this way, of the nou-cai'bonaceous elements of 

 the anthracite would be attended with a disturbance of the molecu- 

 lar equilibrium of the mineral, which would necessitate a new ar- 

 rangement of its particles, and might determine the induction of the 

 crystalline condition characteristic of the diamond. During this pro- 

 cess, the inorganic saline matter, or ash, would either be excluded by 

 the power crystallising bodies are known to possess of expelling hetero- 

 geneous matter, or be included in the crystallising carbon. Either 

 view would consist with observation ; for whilst some diamonds appear 

 to be pure carbon, many leave a slight ash when burned in oxygen. 



The author further observed, that whether anthracite will crys- 

 tallise into graphite or diamond, will be determined chiefly by the 

 temperature at which crystallisation occurs, and the rapidity with 

 which it proceeds. Graphite represents the condition of most stable 

 equilibrium, which the crystalline molecules of carbon assume, when 

 aggregated rapidly at a high temperature. The diamond, on the 

 other hand, has all the characters of a crystal which has formed very 

 slowly at a lower temperature, and it will not change into graphite, 

 unless it be suddenly exposed to an intense heat. Whenever, there- 

 fore, carbon crystallises very slowly at ordinary temperatures, it may 

 be expected to become the diamond rather than graphite, and the 

 latter must be considered as a substance which, when not main- 

 tained at an elevated temperature, is liable to re-arrange its par- 

 ticles in the condition of more stable equilibrium characteristic of 

 the diamond. The author, at the same time, observed, that he did 

 not seek to affirm that all diamonds had been produced from anthra- 

 cite or graphite, but thought it, on the other hand, probable, that, 

 like other crystallisable substances, carbon might be crystallised in 

 various ways. 



2. On the Proportion of Fluoride of Calcium present in the 

 Baltic. By Professor Forchammer of Copenhagen. With 

 some preliminary Remarks on the presence of Fluorine 

 in different ocean waters. By Dr George Wilson. 



Dr Wilson reminded the Society that he had announced to them 

 in 1846 the occurrence of fluorine in the water of the Frith of 



