June 25, 1908] 



NATURE 



177 



vent further infection of the garrison by this vehicle, 

 and the results are strikingly displayed in two charts. 

 In iqo5 the number of cases was 643; in 1907, after 

 the preventive measures came into force, seven cases 

 were admitted from Malta fever. Surely further argu- 

 ment is unnecessary to prove the value of the method 

 which can adduce such results. 



On June iq the Research Defence Society held its 

 inaugural meeting in the hall of the Royal .Society of 

 Medicine, 20 Hanover Square. There was a very 

 gratifying attendance of members, nearly half those 

 present being ladies. The honorary secretary of the 

 society, Mr. Stephen Paget, read the report of the 

 committee, and stated that he had received a number 

 of letters from members regretting their inability to 

 attend the meeting. The Earl of Cromer, the presi- 

 dent of the society, vvas in the chair, and delivered a 

 very telling speech, which has appeared in the daily 

 Press, and which was directed to show that there is 

 little or no pain inflicted in the methods used in ex- 

 periments oh animals in this country, and that in this 

 way alone is there any prospect of further advance in 

 medicine. The first motion approving of the aims 

 of the society was moved by .Sir Thomas Barlow and 

 seconded by Lord Robert Cecil ; the second one, ap- 

 proving of the formation of branches, was moved by 

 Mr. Walter Long, who, referring to his experiences 

 in stamping out rabies, stated that he was inspired to 

 do so only by his faith in Pasteur's results, and was 

 seconded by Prof. C. J. Martin. The very successful 

 meeting was closed by a vote of thanks to the presi- 

 dent for his speech, and for the keen interest he took 

 in the society, which was moved by Mr. Butlin and 

 seconded by the Hon. Sydney Holland. 



ARTIFICIAL DIAMONDS. 

 T^OR some time past the daily Press has been in- 

 -'- terested in the production of diamonds artificially. 

 Long articles have been written upon the subject, and 

 various persons, scientific and otherwise, interviewed, 

 owing to the prosecution of M. Lcmoine by .Sir Julius 

 W'ernher on account of his failure to produce diamonds 

 by chemical means after he had stated he was able to 

 do so, and, in fact, had promised to produce diamonds 

 of very large size at a price which would compete 

 readily with the natural product. However, after 

 obtaining large sums of money to build a factory, and 

 apparently carrying out experiments in which small 

 diamonds were supposed to be obtained, M. Lemoine 

 entirely failed to produce large ones. When diamonds 

 said to have been produced in the crucibles were 

 critically examined, experts were able, not only to 

 assure the magistrate that these diamonds were not 

 artificial, but were also able in several cases to iden- 

 tify them as stones which had been bought from 

 known sources. The whole case hinged upon a certain 

 envelope which was originally lodged in an English 

 bank, and in which it was stated a formula was con- 

 tained by means of which diamonds could be produced 

 artificially. On Tuesday, June 16, this envelope was 

 to bo opened before the magistrate, but in the mean- 

 time the modern alchemist had vanished. When the 

 letter was opened, according to the Times of June iS, 

 the following particulars were found : — 



" 1, the undersigned Henri Lemoine, declare that to 

 make artificial diamonds, it is sufficient to employ the 

 following process: — (i) take a furnace; (2) take some 

 powdered sugar carbon ; (3) place the carbon in a crucible ; 

 (4) place the crucible in the furnace and raise the tempera- 

 ture to from 1700° C. to 1800° C. in order to obtain 

 crystallisation ; (5) when this high temperature has been 

 obtained apply pressure to the cover of the crucible. The 

 diamonds will then be made, and it remains only to take 

 them out." 



NO, 2017, VOL. 78] 



From this it will be noticed that the formula contains 

 absolutely nothing new; sugar carbon, being the 

 purest form of amorphous carbon, has always been 

 the starting product when any successful attempts to 

 prepare diamonds have been made. Consequently those 

 daily papers which ridiculed the process because of 

 the fact that sugar carbon was one of the ingredients, 

 showed want of knowledge of the subject. However, 

 now that the whole formula is made public, it is, 

 to say the least of it, absurd. 



It will be noticed that the carbon is to be placed in a 

 crucible and heated to from 1700° C. to 1800° C, and 

 then pressure is to be applied to the cover of the crucible. 

 When, in 1896, Moissan succeeded in obtaining dia- 

 monds artificially, he did subject sugar carbon, when 

 at a very high temperature, to a verv great pressure. 

 It will be remembered that sugar carbon was dissolved 

 in molten iron, and the crucible containing this was 

 heated toa temperature of 3000° C. to 4000° C. While 

 at this high temperature the crucible and its contents 

 were plunged into cold water or mercury in order to 

 cause rapid solidification. When carboniferous iron 

 is cooled, it expands in the act of solidifying. By 

 suddenly quenching the iron, a solid layer or 

 crust is obtained outside the molten metal ; conse- 

 quently when the inside layer commences to solidify 

 it expands, and thus, as it is encompassed with a 

 solid crust, enormous pressure is exerted. On dis- 

 solving away the iron by means of acids, minute 

 crystals of diamond were produced. 



About the same time Marjorana, by heating a small 

 piece of carbon in an electric arc and then suddenly 

 compressing it by driving a piston down upon it with 

 enormous force, the force being produced by firing a 

 charge of powder in the piston chamber (Nature, 

 June 7, 1900), also obtained minute diamonds. 



In 1905 .Sir Andrew Noble exploded cordite in closed 

 steel cylinders, when it was calculated that a tempera- 

 ture of 5100° C. was obtained and a pressure of 50 tons 

 per square inch. Sir William Crookes examined some 

 of the carbon deposited, and found it to contain minute 

 diamonds. It would appear, therefore, that M. 

 Lemoine exploited results well known in the scientific 

 world in order to deceive people engaged in the dia- 

 mond industry. 



It is a rather remarkable fact that although amor- 

 phous carbon can be converted into graphite, and 

 diamond may also be converted into graphite, as was 

 recently shown by Parsons and Swinton, who obtained 

 graphite from diamond by rapid bombardment with 

 kathode rays, it does not appear possible to convert 

 graphite into diamond. It has been found that when 

 amorphous carbon and graphite are heated to a tem- 

 perature of 3600° C. in the electric arc in an atmo- 

 sphere incapable of acting chemically upon carbon, 

 they vapourise without first liquefying, and on 

 cooling condense to form crystals of graphite. Dia- 

 mond, on the other hand, is first converted into 

 graphite, then vapourises, and on condensation forms 

 graphite. It thus appears that carbon must be in a 

 dissolved condition, and must be cooled under pres- 

 sure in order for a diamond to crystallise out. Pos- 

 sibly, therefore, we shall never be able to obtain the 

 conditions necessary for producing large diamonds in 

 the laboratory. Low down in the earth's crust 

 carbon may be dissolved in iron or other substances, 

 and may at high teinperature be subjected to enormous 

 pressure, such as we, even with the wonderful 

 machinery at our command, and capable of exerting 

 pressures of thousands of tons, have not contemplated. 

 In the earth also the cooling while under this pressure 

 will be slow, and therefore there are the conditions 

 necessary for the growth of large crystals. 



Although in nature diamonds are found in pipes of 



