;7o 



NATURE 



[February i6, 1893 



T, and so on. Wheti the pump has made a few strokes 

 in this manner, a lever T is let down, so as to rest 

 on the ledge u. The wheel F provided with 

 six pegs is now turned a tooth farther each time the 

 weight C slides from the left to the right, and the ledge- 

 peg/, which when the lever was raised caught each time 

 into a notch of the peg-wheel, rests for the length of five 

 strokes of the pump against the circumference of the 

 wheel, and does not catch into the notch until the sixth 

 stroke. As the rising of the quicksilver in the pump is 

 in the inverse proportion of the momentum of the 

 counter-weight in its left final position, if the ledges and 

 peg/ are rightly placed, it will when ascending be driven 

 five times into the little hollow space r.-, and only at "the 

 sixth into the ball n. In consequence of this the little 

 air-bubbles are accumulated in the highly evacuated 

 space t\ in which they ascend owing to the slight counter- 

 pressure, and forming larger bubbles, and having easily 

 overcome the somewhat greater counter-pressure of the 

 mercury column s-^ they rise into the ball P. 



All these manipulations are performed entirely auto- 

 matically by the apparatus. At the same time that the 

 toothed wheel has commenced working {i.e. when the 

 volume of air pumped out by the pump has sufficiently 

 diminished) the vessel P is entirely cut off from the 

 hydrostatic air-pump by the cock /„ thus ceasing to act. 

 The mercury of the pump is entirely shut off on both 

 sides from the exterior air, and only in contact with 

 perfectly dry air. After stopping the pump, concentrated 

 sulphuric acid may be sucked up into P, which dries up 

 entirely. The mercury is shut off" from M by a caout- 

 chouc bag, I. 



The following experiments were made at the Physical 

 Institute of the University of Berlin : 



400 c.cm. (cubic centimetres) were evacuated to i/iooo 

 m.m. in ten minutes ; 4000 c.cm. = 4 litres, in an hour. 



The highest rarefaction hitherto obtained has been 

 about from 1/6000,00 — 1/800,000 m.m. = to about 

 fFioooodoo - (ioooJoooo atmospheres. 



The pump is supplied by Messrs. E. Leybolds Nach- 

 folger, Cologne (Germany). AUGUST Raps. 



CRYSTALLISED CARBON. 



IN the course of some researches on the properties and 

 modes of formation of the various forms of carbon, 

 M. Henri Moissan has bucceeded in reproducing the 

 variety of diamond known as carbonado^ or black diamond, 

 and has even obtained some minute crystals of the colour- 

 less gem. An account of his results in the Comptes 

 Rendus of February 6 is followed by an article on the 

 reproduction of the diamond, by M. Friedel, and some 

 congratulatory remarks by M. Berthelot. 



As long ago as 1880 Mr. Hannayi indicated the for- 

 mation of diamond-like crystals on heating under high 

 pressure, in a tube of iron, a mixture of lithium, lamp- 

 black, essence of paraffin, and bone oil. It was then 

 supposed that the nitrogenous compounds of the last 

 substance played the most important part. In M. 

 Moissan's new process carbon obtained from sugar is 

 dissolved in a mass of iron, and allowed to crystallise out 

 under high pressure. To produce this pressure the ex- 

 pansion of iron during condensation is utilised. The 

 carbon is strongly compressed in an iron cylinder closed 

 with a screw- stopper of the same metal. A quantity of 

 soft iron, weighing about 150 or 200 gr., is melted in the 

 electric furnace in a few minutes, and the cylinder is 

 plunged into the molten mass. The crucible is at once 

 taken out of the furnace and splashed over with water. 

 When the external crust is at a red heat the whole is 

 allowed to cool slowly in air. 



The metallic mass thus obtained is attacked by boiling 



hydrochloric acid until all the iron is removed. There 

 remain three forms of carbon : graphite in small 

 quantity ; a chestnut-coloured carbon in very small 

 needles, such as has been found in the Canon Diablo 

 meteorite ; and a small quantity of denser carbon which 

 has to be further isolated. For this purpose the mixture 

 is treated alternately with boiling sulphuric and hydro- 

 fluoric acids, and the residue decanted in sulphuric acid 

 of density i'8. It then contains only very little graphite, 

 and various forms of carbon. After six or eight treat- 

 ments with potassium chlorate and fuming nitric acid, the 

 residue is boiled in hydrofluoric acid and decanted in 

 boiling sulphuric acid to destroy the fluorides. It is then 

 washed and dried, and bromoform is employed to separate 

 out some very small fragments denser than that liquid, 

 which scratch the ruby, and, when heated in oxygen at 

 1000°, disappear. 



Some of these fragments are black, others transparent. 

 The former have a rough surface, and a greyish black 

 tint identical with that of certain carbonadoes ; they 

 scratch the ruby, and their density ranges from 3 to 3"5. 

 Some pieces have a smooth surface, a darker colour, and 

 curved edges. The transparent fragments, which appear 

 broken up into small pieces, have a fatty lustre, are highly 

 refractive, and exhibit a certain number of parallel striae 

 and triangular impressions. 



During combustion in a current of oxygen at 1050", 

 some of the fragments left cinders of an ochreous colour, 

 usually preserving the original form of the small crystal — 

 just as in the combustion of impure diamonds. 



As indicated already by Mr. Sidney Marsden,' silver 

 heated to 1500° in presence of sugar carbon is found to 

 contain on cooling some black crystals with curved edges. 

 M.; Moissan has found that high pressure is indispensable. 

 He heated silver till it boiled briskly in contact with car- 

 bon, and found that a certain quantity of the latter was 

 dissolved. By suddenly cooling in water, a portion of 

 liquid silver, cooling inside a sohd crust, was subjected to 

 a very high pressure. No diamonds were formed, but 

 rather a large crop of carbonadoes of densities ranging 

 from 2-5 to 3'5, thus forming a series connecting graphite 

 with diamond. Bromoform separated a carbonado, which 

 scratched the ruby and burned in oxygen at looo^ A 

 quantitative determination of this reaction showed that 

 o'oo6 parts of this substance gave 0-023 of carbonic acid. 

 M. C. Friedel describes an experiment in which he 

 obtained a black powder capable of scratching corundum 

 by the action of sulphur on molten iron containing 4 per 

 cent, of carbon. But the question of the production of 

 diamond powder by this means is as yet an open one. 



M. Moissan is continuing his researches on the solu- 

 bihty of carbon in iron, silver, and their alloys. It is to 

 be hoped that he will soon be able to exhibit artificial 

 true diamonds of a more imposing size. 



LINES OF STRUCTURE IN THE 



WINNEBAGO CO. METEORITES AND IN 



OTHER METEORITES:' 



•"PHE ground and polished surface of a Winnebago Co. 

 A meteorite showed to me some interesting markings. 

 Subsequent examination revealed like markings in other 

 meteorites. Perhaps these markings have been de- 

 scribed. If so I have no recollection o<" the description, 

 and therefore it seems worth while to call attention to 

 them. 



The polished surface of a small Winnebago stone, three 

 or four square centimetres in area shows several hun- 

 dreds of bright metallic points. The larger iron particles 

 in this surface have great varieties of shapes— the smaller 



NO. 



1 Proc. Roy. Soc, vol. xxx. p. iS 

 I 2 16, VOL. 4.7] 



1 Pioc. Roy. Soc. Ed. 1880. vol. ii. p. 20. 



2 Reprinted from the February number of the A 

 Science. 



Journal of 



