80 
THE HON. Sm CHAELES ALGERNON PARSONS : EXPERIMENTS ON 
semi-transparent, the gas present being chiefly hydrogen. (Paper by Parsons and 
SwiNTON, January 16, 1908, ‘Roy. Soc. Proc.,’ A, voL 80.) 
In this latter experiment the surface action appeared to be much less in proportion 
to the incipient change of the under layer to graphite, and the impression is that at 
1890° C. the temperature of bulk transformation is being approached, also that 
carbon monoxide, carboA dioxide, nitrogen, hydrogen, and iron, one or more, act as 
catalysts in the change of diamond to graphite. 
Experiments on the Oxidation of Alloys of Iron ivhen Molten. 
Iron was melted in a carbon crucible and highly carburized ; when it had somewhat 
cooled, the other elements were added, in small percentages of aluminium, silicon, 
calcium, magnesium, manganese, iron sulphide, collectively and in some cases singly ; 
the crucible was then removed from the furnace and superheated steam blown 
through a carbon tube into the metal; energetic action took place and much heat 
was evolved; on analysis, after destroying the graphite, a bulky transparent 
crystalline residue remained. 
With aluminium alone the crystals were chiefly crystallized alumina, and with the 
other elements tlie spinels and other crystals were produced ; all were transparent 
and colourless, but when chromium was added some rounded crystals occurred 
resembling pyrope. When submitted to sulphur dioxide and carbon dioxide the 
result was the same, but less residue was produced. Under the microscope there 
appeared to be a small proportion of very small crystals like diamond ; these burnt 
in oxygen. When the l)ulky residue was placed in a test-tube with the double 
nitrate of silver and thallium, and the density adjusted so that a diamond floated 
midway between the top and bottom, there collected into its immediate neighbourhood 
after a time an amount of the small crystals which was estimated to be about 5 per 
cent, of the total residue. 
One prolonged treatment of hydrofluoric acid had no apparent effect on the bulky 
residue, and it required so many treatments to destroy it that we failed to isolate the 
very small particles whose size did not exceed mm.; they were probably lost by 
flotation. These experiments were repeated many times with the same result, but 
they merit further investigation, with steam under high pressure and conditions 
favourable to the formation of larger crystals. 
Note. — Marsden observed in silver the association of black diamond with 
crystalline alumina, silicide of carbon, &c., ‘ Roy. Soc. Proc.,’ 1880. 
Experiments in Vacuo. 
The presence of diamond in some meteorites suggested a series of experiments 
under various degrees of vacuum up to the highest obtainable.* 
* Also an impression suggested itself in 1907 that hydrogen had an adverse effect on the formation of 
diamond. 
