13^ 



KNOWLEDGE & SCIENTIFIC NEWS. 



rj.) 



1905. 



Ephemeris for Observations of Comet 

 1904 II. 



(i^h.. Berlin Mean Time 



CHEMICAL. 



Bv C. A. MiTCHKLL. B..A. ii i.xoii.i, F.I.C, 



New Experiments on the Making of 

 Diamonds. 



A BLOCK of meteoritic iron troin Canon Diablo was recently 

 examined by Professor Moissan, and its composition sug- 

 gested improvements in the artificial manufacture of diamonds. 

 A section of the meteorite contained numerous diamonds, 

 both black and transparent, together with amorphous carbon 

 (graphite), and phosphorus and sulphur combined with iron. 

 Experiments were therefore made to determine the influence 

 of sulphur, silicon, and phosphorus upon the crystallisatioa 

 of carbon under the artificial conditions of the laboratory. 

 Iron was fused with a large e.xcess of sugar in a crucible in an 

 electric furnace, and as soon as the molten iron had become 

 saturated with carbon (derived from the sugar) a small pro- 

 portion of iron sulphide was introduced, and the crucible then 

 rapidly cooled by immersion in cold water. It was found that 

 the carbon had crjstallised out in diamonds from the centre 

 of the mass, and that the iron sulphide had considerably in 

 creased the yield of crystals. Rapid cooling of the fused 

 mass, however, was essential, for otherwise no diamonds were 

 formed. Silicon also promoted the crystallisation of the 

 carbon, but phosphorus had no effect upon the results. 

 • • • 

 The Specific Servim Test as a Proof of 



Evolution. 

 Professor Haeckel in his latest work the " l-.volution of 

 Man," cites the recent results of physiological chemistry as 

 additional proofs of the origin of man. Although a serum 

 that has been rendered specific for one species of animal 

 should give no precipitate with the sera of other animals (see 

 Knowledok & SfiK.NTiiK Nf.ws this vol. p. 86), the test 

 breaks down in the case of animals of very closely allied 

 species, and hence it is not surprising that a preparation that 

 has been made specific for human serum should also react 

 with the serum of an anthropoid ape and vice versa. It 

 would thus be impossible to infer that a given stain consisted 

 of human blood it there were a possibility of an anthropoid 

 ape having been near the place. Another possible source of 

 error in the serum test has been pointed out by MM. 

 Linossier and Lemoine, who find that the differences are not 

 so pronounced as has been asserted. They slate that if solu- 

 tions of too great a concentration be employed, the prepared 



sera are no longer absolutely specific, although the preci- 

 pitates are much more marked with the serum of an animal 

 of the particular species in question than with the sera of 

 animals of other species. To obviate this error they recom- 

 mend that the solutions employed should not contain more 

 than one part in a thousand. 



* « » 



The Preparation of Pure Ta.ntalunn. 



The rare metal tantalum occurs in various minerals, such 

 as niobite, tantalite, and samarskite, and is usually found in 

 association with another rare metal, niobium. Hatchett, in 

 1801, came to the conclusion that some of these minerals con- 

 tained a new element, and different chemical compounds 

 containing it were subse(|ueDtly prepared. It is only quite 

 recently, however, that Dr. \\". von Bolton has succeeded in 

 preparing the metal in a state of purity, and in his opinion 

 the substance prepared by M. Moissan in his electric furnace 

 was contaminated with carbon. Dr. Bolton's method of ob- 

 taining it consists in passing an electric current through a 

 filament of brown tantalum oxide in a globe from which the 

 air has been previously exhausted by means of a vacuum 

 pump. This causes oxygen to be evolved from the incan- 

 descent filament, which gradually turns grey as it is reduced 

 to the metallic state. Tantalum can also be prepaied by 

 fusing tantalum fluoride with potassium in a vacuum by means 

 of an electric furnace. Metallic tantalum, which has an 

 atomic weight of about iSo, is extremely ductile. When the 

 sheets are again heated and hammered they become ex- 

 tremely hard, and the metal may find a possible use as a 

 substitute for the diamond in drills. Tantalum resists the 

 action of acids, including iKjiin ligin, and it can be heated to 

 redness in the air without burning. It forms alloys with 

 many other metals, but apparently does not amalgamate with 

 mercury. When combined with about one per cent, of carbon 

 it becomes very brittle. Messrs. Siemens and Halske have 

 employed filaments of tantalum for electric incandescent 

 lamps, and as a length of over 20 inches is necessary for a 

 lamp of 22candle power, they have constructed a special 

 lamp for the purpose. The central support Un- the filament is 

 of glass and has a number of radiating supports over which 

 the wire is stretched. This lamp is stated to consume only 

 half the electric energy required by the ordinary incandescent 

 lamp, while a pound of the tantalum is sufficient for more 

 than 20,000 lamps, so that a great saving is effected by its use. 



GEOLOGICAL. 



By EmvAuii A. Maktin, F.G.S. 



Gravels on South Norwood Hill. 



W'k have received a couiinunicaticjii from .Mr. J. K. I^arkby in 

 regard to the reputed eoliths found at the top of the hill by 

 Mr. .\. F. Kobarts, F.G.S., two years ago, to which a reference 

 was made last month. He has been unable to accept the 

 flints as true eoliths, and it is to fair to say that others have 

 questioned their authenticity. On the other hand they have 

 been accepted as of human workmanship by many of the best 

 local geologists, and they deserve mention in any work dealing 

 with implemeiitiferous gravels. We shall all agree with Mr. 

 Larkby when he says : " Whilst fully accepting the artificial 

 nature of eolithic forms, I recognise that the indiscriminate 

 admission of evidence must serve to confirm the impression 

 that the acceptor of eoliths is ipso /ado a ' crank.' " 

 « • • 



A Lost R.iver. 



The gravel which is found .iloiig the valley which leads from 

 Caterham to Purley gives evidence of an important river which 

 at one time flowed here. Early last year there was evidence 

 of the stream in the rising again of what is known locally as 

 the Bourne. This had not flowed since 1H96, although previous 

 flowings had generally occurred at shorter intervals. The 

 rising of the feeders were to be seen at various spots in the 

 valley, e xtending from the grounds of the " Hose and Crown " 

 at Warlingham, where they were seen bubbling up at several 

 places, notably on the site of the cocoa-nut pitch, to the gas- 



