450 



Mr. J. B. Hannay. 



[May 27, 



VI. " On the Artificial Formation of the Diamond." By J. B. 

 Hannay, F.R.S.E., F.C.S. Communicated by Professor G. 

 G. Stokes, LL.D., D.C.L., Sec. K.S. Received April 15, 

 1880. 



In a preliminary notice, which the Royal Society has done me the 

 honour of publishing in the '* Proceedings," I gave a very ohort 

 sketch of the work I have done which led me to a reaction whereby 

 hard crystalline carbon has been produced. I have now the honour of 

 laying a detailed account of the methods and results before the Society. 

 As far back as September, 1879, I was searching for a solvent for the 

 alkali metals, and tried experiments with many liquids and gases, but 

 invariably found that when the solvent reached the permanently 

 gaseous state chemical action ensued. This was the case even with 

 hydrocarbons, the metal combining with the hydrogen and setting free 

 the carbon. Paraffin spirit, boiling at 75°, was first used in experi- 

 menting, and the spirit contained a considerable amount of olefines ; 

 but even these unsaturated hydrocarbons seemed to be split up in like 

 manner. The experiments were conducted in thick tubes from 1 to 

 1*5 millims. internal, and 10 to 15 external, diameter, and made of 

 hard glass. In some cases when the carbon was set free, a consider- 

 able proportion of the hydrogen seemed to have combined with the 

 higher olefines and paraffins, rendering them gaseous, most of the gas, 

 however, being formed by the reaction discovered by Thorpe and 

 Young, where a high paraffin splits up into lower olefines and paraffins. 

 This reaction, I would remark in passing, is not always the only one to 

 take place, as a mixture of lower paraffins and olefines on being heated 

 under very high pressure sometimes yield a small quantity of a higher 

 or even nearly solid paraffin, as well as gaseous products. An attempt 

 was made to obtain solid paraffin in quantity by this method, but only 

 traces were obtained white enough for use. 



The alkali metal which decomposes the hydrocarbon retains a quan- 

 tity of pure hydrogen, which may be seen by exhausting it by the 

 Sprengel pump. A piece of sodium was exhausted in the molten 

 state for five hours by the Sprengel pump, and when no more 

 hydrogen had been evolved for an hour, a piece was placed in a tube 

 with paraffin spirit and heated for two hours, and when a considerable 

 quantity of carbon was deposited, as much of it was removed as could 

 be conveniently obtained and agaiu exhausted, when 32 times its 

 volume of hydrogen was extracted from it. This was repeated several 

 times, and quantities of hydrogen, varying from 17 to 25 times the 

 volume of the sodium, obtained. The carbon deposited on the tube is 

 of a hard scaly nature, and when the sodium is slowly oxidized and 



