July 28, 1887] 



NA rURE 



)05 



been forgotten, and is without record in modern 



iteoric literature. The crystals— of the size, number, 



d completeness of which Haidinger makes no mention 

 — were obtained by him from a nodule of graphite which 

 had dropped out of the Arva meteoric iron, and chiefly 

 from a study of their form he inferred that they were 

 pseudomorphous after iron pyrites. Even yet no iron 

 pyrites, crystallized or massive, has been found in a 

 meteorite, the meteoric sulphide of iron being, not the 

 bisulphide, but the protosulphide : further, Gustav Rose, 

 after examination of the crystals, expressed the opinion 

 that the replacement of the edges of the cubes was 

 suggestive rather of holosymmetry than of hemisymmetry, 

 an interpretation which would exclude iron pyrites as a 

 possible antecedent mineral. 



The Youndegin graphitic crystals support the view 

 entertained by Rose : the existence of the dodecahedron 

 face, of which there is goniometrical proof, is of itself 

 quite sufficient to show that the crystalline form is distinct 

 from that of iron pyrites. 



The iron pyrites theory being discarded, and the fact 

 being recognized that no mineral constituent of meteorites 

 has yet been found which crystallizes in forms similar to 

 those of the graphitic crystals, there naturally arises a 

 feeling of doubt as to the correctness of the view accord- 

 ing to which they are of pseudomorphic origin, and thus 

 a question as to whether they may not possibly be a third 

 allotropic condition of crystallized carbon presenting the 

 general characters of graphite, but a crystalline form 

 frequent in the diamond. 



Bischof denies the possibility of explaining the pseudo- 

 morphism of terrestrial minerals by any other process 

 than the slow action of water, of which there is no evi- 

 dence in meteorites ; and though it would be unsafe to 

 argue that only in this way could meteoric pseudomorphs 

 be produced, there is sufficient difficulty in their explana- 

 tion to demand strong evidence before the pseudomorph- 

 ism of the graphitic crystals is granted, more especially 

 when we have regard to the fact that no other graphitic 

 pseudomorph has yet been established either in meteoric 

 or in terrestrial minerals. 



Examination of the Youndegin crystals under the 

 microscope shows that some of them are hollow, and 

 appear to be built up of successive cubical shells : on 

 several of the crystals there are globular growths cover- 

 ing a large part of a cube-face, and occasionally the 

 globule is broken, and is seen to be merely a thin, now 

 empty, shell, of which the bottom is the face of the cube. 

 The crystals are easily frangible, and no cleavages were 

 observed : they appear to be quite homogeneous in their 

 material. 



Although some of these characters suggest a pseudo- 

 morphic origin of the crystalline form, it cannot be said 

 that they prove it. Both of the recognized crystalline 

 forms of carbon, graphite and diamond, have long been 

 standing difficulties for the crystallographer. As already 

 pointed out, the crystals of graphite are rarely more than 

 mere tables, of which there is a controversy as to the 

 crystalline system ; those of the diamond are often so 

 different in their geometrical characters from the crystals 

 of every other known substance, that it cannot be satis- 

 factorily determined whether they are to be referred to a 

 holosymmetric or to a hemisymmetric type. 



Hollow and skeleton crystals are often the result of a 

 hurried crystallization, as is so well seen in the artificial 

 crystals of bismuth and of common salt. The diamond, too, 

 when in cubes, has faces more uneven than those of the 

 Youndegin crystals, and shows usually the same replace- 

 ment of its edges by rounded faces of tetrakishexahedra. 



It thus might be argued with some force that the 

 Youndegin crystals have been the result of a hurried 

 crystallization of carbon, and that, while striving to reach 

 a dignity which has been assigned to cubes of diamond, 

 they have been overtaken by misfortune and come out in 



cubes of the less honoured mineral, graphite. The obtuse, 

 almost flat, square pyramid seen on some of the cube- 

 faces, the hollow globular growths, the occasional parallel- 

 ism of the grouping of the cubes are distinct, however, 

 from what is met with in the diamond. 



And after consideration of all the observed characters 

 of these crystals it will be seen that the explanation of 

 the occurrence of the crystals in the interior of a mass of 

 iron by means of pseudomorphism is untenable. Though 

 the easy frangibility, the absence of evidence of cleavage, 

 the hollowness, and the occasionally crust-like structure, 

 are more or less characteristic of pseudomorphic crystals, 

 they are not incompatible with an independent crystalliz- 

 ation : on the other hand, while the superior hardness 

 distinguishes the crystals from those of native terrestrial 

 graphite, the separateness, completeness, and general 

 excellence of the crystals, the delicacy of various acicu- 

 lar projections, and more especially of the obtuse, almost 

 flat, square pyramid seen on some of the cube-faces, are 

 sufficient to prove that the crystalline form never had a 

 previous tenant. The delicacy of the acicular projections 

 is such that the crystals must have been formed in situ. 

 In case of pseudomorphism the elements of the original 

 mineral ought to be in the vicinity of the crystals, and 

 there ought to be an excess either of the original mineral 

 or of the replacing amorphous graphitic carbon : both are, 

 however, conspicuous by their absence, and in this frag- 

 ment of the iron the whole of the graphitic carbon is 

 present as cubic crystals. 



On examination of a large graphitic nodule from the 

 Cocke County meteoric iron, now in the British Museum, 

 crystals of graphitic carbon, cubo-octahedral in form, are 

 to be seen in some of the crevices. 



There can be absolutely no doubt that the graphitic 

 crystals are the result of crystallization of the meteoric 

 graphite, and that they represent a third allotropic condi- 

 tion of crystallized carbon, the general characters being 

 those of graphite, and the crystalline system that of the 

 diamond. 



As this form of graphitic carbon is unknown among 

 terrestrial minerals, and has so important a bearing on 

 the formation of meteoric graphite, it may conveniently 

 receive a special name ; I suggest the term " cliftonite," 

 after Prof. R. B. Clifton, F.R.S., who has long been in- 

 terested in the physical characters of minerals, and has 

 done much to encourage their study. 



A full description of the meteoric iron itself and of the 

 graphitic crystals will appear in the forthcoming number 

 of the Journal of the Mineralogical Society, 



L. Fletcher. 



NOTES. 



We are glad to learn that at the Naval Review (some lessons 

 suggested by which we may refer to in a future number) 120 

 official invitations were sent out to men of science, while many 

 were hospitably entertained by the Peninsular and Oriental, the 

 Orient, the British India, and the Cable-Laying Companies. 

 Some time next century we may hope that the existence of 

 science, of a Royal Society, and of eminent scientific men 

 employed in the public departments, may dawn upon the then 

 Lord Chamberlain. 



The Jubilee dinner of the Electric Telegraph, which is going 

 on as we go to press, is a brilliant affair, to which we shall refer 

 at length next week. 



We print to-day the text of the Technical Education Bill. It 

 was absolutely necessary that some such measure should be 

 introduced, and we may hope that as it has no relation to party 

 politics it will be passed without much difficulty. One change 

 in the Bill ought certainly to be made. According to the fourth 

 clause, there is to be no payment out of the local rate in respect 

 of a scholar unless or until he has passed the sixth standard. This 

 may be a very proper provision so far as boys are concerned ; 



