[ 67 ] 



III. BAKEKIAN LECTURE, 1918. Experiments on the Artificial Production 



of Diamond. 



By the Hon. Sir CHAKLES ALGERNON PARSONS, K.C.B., F.R.S. 



Lecture delivered April 25, MS. received July 15, 1918. 



CONTENTS. Page 



Introductory 57 



Experiments under High Pressure 69 



designed to melt Carbon under Pressure by Resistance Heating 70 



ii )> v ,> ,, the Rapid Compression of Flame . . 71 



with High-velocity Bullets 72 



,, on Pressure in Cast Iron when Cooled 7.") 



Gases ejected from Cast Iron on Setting ., 7(i 



Other Experiments 77 



Experiments at Atmospheric Pressure 78 



on the Conversion of Diamond to Graphite 7 !) 



Oxidation of Molten Fe Alloys 80 



in Vacuo SO 



,, High Vacuum S2 



under X-ray Vacuum ... 8-1 



Summary and Conclusions 85 



Appendix Schedule of Experiments 92 



IN this paper is given an account of experiments on the artificial production of 

 diamond which I commenced in 1887, and have carried on intermittently till the 

 commencement of the War, when they were interrupted. Although the account is 

 not as full as I could have wished, yet it is hoped that from the description of such 

 experiments as relate to the salient features, followed by a summary of their bearings 

 upon the research, and the conclusions at which we have arrived, together with an 

 Appendix stating briefly the character of about one-third of the total number of 

 experiments, a fair idea may be gathered of this research. 



One reason for writing this paper at the present time has been a publication on 

 the same subject by OTTO RUFF in ' Zeitschrift f'iir Anorganische Chemie,' vol. 99, 

 pp. 73-104, May 25, 1917, who also referred to the work of LTJMMER on the 

 apparently molten aspect of the surface of the carbon of the electric arc. 



In my paper to the Royal Society in 1888 were described experiments where 

 a carbon rod heated by a current of electricity (fig. l) was immersed in liquids at 

 pressures up to 2200 atmospheres, and where the liquids, benzene, paraffin, treacle, 

 chloride and bisulphide of carbon, were found to yield deposits of amorphous carbon. 



In my paper of 1907 allusion was made to experiments in liquids at a pressure of 

 4400 atmospheres, and to the distillation of carbon in carbon monoxide and dioxide 

 at this pressure with similar results, also to an attempt to melt carbon at pressures 



VOL. CCXX. A 573. L [Published December 16, 1919. 



