Open AccessA new formation of diamond
Author(s) -
William Crookes
Publication year - 1905
Publication title -
proceedings of the royal society of london. series a, containing papers of a mathematical and physical character
Language(s) - English
Resource type - Journals
eISSN - 2053-9150
pISSN - 0950-1207
DOI - 10.1098/rspa.1905.0051
Subject(s) - boiling point , melting point , carbonic acid , diamond , critical point (mathematics) , carbon fibers , chemistry , boiling , arsenic , absolute (philosophy) , freezing point , thermodynamics , materials science , physics , organic chemistry , mathematics , composite material , mathematical analysis , philosophy , epistemology , composite number
On the average the critical point of a substance is 1·5 times its absolute boiling-point. Therefore the critical point of carbon should be about 5800° Ab. But the absolute critical temperature divided by the critical pressure is for all the elements so far examined never less than 2·5; this being about the value Sir James Dewar finds for hydrogen. So that, accepting this, we get the maximum critical pressure as follows, viz., 2320 atmospheres:— 5800° Ab./CrP = 2·5, or CrP = 5800° Ab./2·5, or 2320 atmospheres. Carbon and arsenic are the only two elements that have melting-point above the boiling-point; and among compounds carbonic acid and fluoride of silicium are the only other bodies with similar properties. Now the melting-point of arsenic is about 1·2 times its absolute boiling-point. With carbonic acid and fluoride of silicium the melting-points are about 1·1 times their boiling-points. Applying these ratios to carbon we find that its melting-point would be about 4400°.