422 



NATURE 



[March 4, 1880 



carbon might be deposited in the crystalline state. After 

 a large number of experiments, it was found that ordinary 

 carbon, such as charcoal, lampblack, or graphite, were 

 not affected by the most probable solvents I could think 

 of, chemical action taking the place of solution. 



A curious reaction, however, was noticed, which seemed 

 likely to yield carbon in the nascent state, and so allow of 

 its being easily dissolved. When a gas containing carbon 

 and hydrogen is heated under pressure in presence of cer- 

 tain metals its hydrogen is attracted by the metal, and its 

 carbon left free. This, as Prof. Stokes has suggested to 

 me, may be explained by the discovery of Professors 

 Liveing and Dewar, that hydrogen has at very high 

 temperatures a very strong affinity for certain metal?, 

 notably magnesium, forming extremely stable compounds 

 therewith. 



When the carbon is set free from the hydrocarbon in 

 presence of a stable compound containing nitrogen, the 

 whole being near a red heat and under a very high 

 pressure, the carbon is so acted upon by the nitrogen 

 compound that it is obtained in the clear, transparent 

 form of the diamond. The great difficulty lies in the 

 construction of an inclosing vessel strong enough to with- 

 stand the enormous pressure and high temperature, tubes 

 constructed on the gun-barrel principle (with a wrought 

 iron coil), of only half an inch bore and four inches 

 external diameter, being torn open in nine cases out of 

 ten. 



The carbon obtained in the successful experiments is 

 as hard as natural diamond, scratching all other crystals, 

 and it does not affect polarised light. I have obtained 

 crystals with curved faces belonging to the octahedral 

 form, and diamond is the only substance crystallising in 

 this manner. The crystals burn easily on thin platinum- 

 foil over a good blowpipe, and leave no residue, and after 

 two days' immersion in hydrofluoric acid they show no 

 sign of dissolving, even when boiled. On heating a 

 splinter in the electric arc, it turned black — a very 

 characteristic reaction of diamond. 



Lastly, a little apparatus was constructed for effecting a 

 combustion of the crystals and determining their composi- 

 tion. The ordinary organic analysis method was used, 

 but the diamond crystals were laid on a thin piece of 

 platinum-foil, and this was ignited by an electric current, 

 and the combustion conducted in pure oxygen. The 

 result obtained was, that the sample (14. mgrms.) con- 

 tained 97'S5 per cent, of carbon, a very close approxima- 

 tion, considering the small quantity at my disposal. The 

 apparatus and all analyses will be fully described in a 

 future paper. 



Extract from a letter from Mr. Hannay, dated February 23. 



" I forgot, in the preliminary notice, to mention that 

 the specific gravity of the diamond I have obtained ranges 

 as high as 3'5 ; this being determined by flotation, using 

 a mixture of bromide and fluoride of arsenic." 



The President having called for any observations on the 

 notice by Mr. Hannay, Mr. Maskelyne said that the 

 present differed from the numerous announcements and 

 other communications that have been heretofore made to 

 scientific societies at various times purporting to record 

 the artificial production of the diamond in this, that here 

 the prjduct so claimed to have been manufactured is 

 really diamond. He had himself proved this by the 

 simple tests of the mineralogist. He had deeply abraded 

 topaz and sapphire with a particle of the substance and 

 abraded them with the greatest ease ; the angle of the 

 cleavages of a crystalline fragment sent him by Mr. 

 Hannay was the angle between faces of the regular octa- 

 hedron, and he had burnt a small grain of the substance 

 on a platinum foil with the characteristic glow of the 

 diamond, and without its leaving a residue. And on 

 polarised light it had no action— or rather one particle 

 had a very slight action, just as many diamonds have when 



turned between crossed tourmalines, and the lustre of the 

 body was truly adamantine. All the particles he had seen 

 as yet were fragments ; none were complete crystals. They 

 were characterised by the laminated structure of diamond. 

 One indeed forwarded to him by Prof. Roscoe had exactly 

 the appearance of a chip from a small diamond that might 

 originally have been from Jth to ^»nd of a carat in size ; 

 it may have been about T J^th of a" carat in weight itself. 

 Prof. Roscoe had recognised the close similarity of this 

 fragment to one of native diamond, and had declared his 

 scepticism of the reality of the transmutation of carbon 

 until it should be proved to be an established scientific 

 result ; and Mr. Maskelyne considered Prof. Roscoe was 

 printdfacie justified in this scepticism, and wished, on the 

 part of Prof. Roscoe, to place on record this hesitation on his 

 part to accept the results claimed by Mr. Hannay without 

 further proof, though no one would accept them when 

 proved with greater pleasure than would Prof. Roscoe. 

 And, on the other hand, Mr. Maskelyne, while supporting 

 warmly the observations of the President, and vindicating 

 for the Royal Society its prerogative of holding a sceptical 

 attitude towards new discoveries, and especially towards 

 one so novel and so long desiderated as this, felt confident 

 that the gentleman whose beautiful investigation had led 

 him up to what might so well be the threshold of this 

 discovery, may, until at least his further communication 

 shall have been made, be fairly credited with the moral 

 qualities that would render any approach to falsification 

 of his results impossible. At the same time the rigid 

 scrutiny of science must be called in to establish or refute 

 those results, and the advantage of such a process and ot 

 the sceptical attitude that dictates it, is all to the advantage 

 of him whose results are thus accepted. Mr. Maskelyne 

 observed that the employment of a nitrogen compound 

 appeared to be a novel and most important feature in 

 Mr. Hannay's process, though what compound he used 

 was not yet publicly announced. One point of difference 

 he had observed in Mr. Hannay's fragments distinguish- 

 ing them from ordinary "cleavage " diamond is that they 

 present sometimes a curbed lamination, which he would 

 designate as a kind of nacreous lamination, like the 

 rounded and parallel scales of mother-of-pearl. Pro?» 

 Stokes subsequently illustrated this by a drawing on the 

 black board. Mr. Maskelyne subsequently explained that 

 his own share in announcing Mr. Hannay's discovery was 

 undertaken with that gentleman's concurrence as asserting 

 his priority of claim. 



Mr. Hulke suggested that the fragmentary character of 

 the diamonds might be due to the disruption caused by 

 gaseous inclosures in them on the removal of the enormous 

 pressure under which they were formed. 



Prof. Dewar remarked that the somewhat indefinite 

 statements in Mr. Hannay's paper of the presence of a 

 stable compound of nitrogen being necessary for the suc- 

 cess of the process bear a strong analogy with known 

 facts regarding the formation of graphite. Until within 

 the last few years the transformation of carbon into the form 

 of graphite had only succeeded by dissolving it in cast- 

 iron. This involves a temperature of twelve or fourteen 

 hundred degrees ; but Dr. Pauli had show n that the oxida- 

 tion of cyanides in crude caustic soda at a temperature 

 not exceeding a low red heat, say 500°, resulted in the 

 production of a quantity of graphite. Now under ordinary 

 conditions of pression diamond will withstand a high 

 temperature without changing into the stable form, 

 and in this it resembles graphite. From all that is 

 known of the thermal relation of diamond and graphite 

 it would appear that the passage from the one state 

 to the other involves little or no absorption or evolution 

 of heat— quite unlike the corresponding changes in the 

 allotropic modification of phosphor ; and therefore it 

 would appear that some such process of separating 

 nascent carbon, probably through the presence of cyanides, 

 at a relatively low temperature and under great pressure, 



