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III. Bakerian Lecture, 1918.— Experiments on the Artificial Productioii 
of Diamond. 
By the Hon. Sir Charles Algernon Parsons, A.C.B., F.R.S. 
Lecture delivered April 25,—MS. received July 15, 1918. 
Contents. Page 
Introductory. 67 
Experiments under High Pressure.69 
„ designed to melt Carbon under Pressure by Resistance Heating.70 
j> n ,) ,, the Rapid Compression of Flame . . 71 
,, vdth High-velocity Bullets.72 
„ on Pressure in Cast Iron when Cooled.75 
Gases ejected from Cast Iron on Setting.76 
Other Experiments. 77 
Experiments at Atmospheric Pressure. 78 
„ on the Conversion of Diamond to Graphite.79 
„ „ Oxidation of Molten Fe Alloys.80 
„ in Vacuo.80 
,, High Vacuum.82 
,, under X-ray Vacuum.84 
Summary and Conclusions.85 
Aj^pendix—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 tlie 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 flir Anorganische Chemie,’ vol. 99, 
pp. 73-104, May 25, 1917, who also referred to the work of Lummer 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 [Publislied December 16, 1919. 
