246 



NATURE 



{Jan. 24, 1878 



was treated, for the separation of the metal, by the analy- 

 tical method of Prof. Bunsen, The mother-liquor obtained 

 after the separation of the rhodium and iridium was heated 

 with an excess of chloride of ammonium and nitrate of 

 ammonium. A dark red precipitate was obtained after 

 calcination at red heat. It yielded a greyish mass 

 resembling spongy platinum. The irgot resulting from 600 

 grammes of mineral weighed o'l"] kil. 



The metal was dissolved in aqua regia, in order to 

 examine the action of different reagents on the solution. 

 Potash gave a clear yellow precipitate of the hydrate of 

 davyum, which is easily attacked by acids, even by acetic 

 acid. The hydrate of davyum dissolved in nitric acid 

 gave a brownish mass of nitrate of davyum ; by 

 calcining this salt a black product is obtained, which is 

 probably the monoxide. 



The chloride of davyum, dissolved in a solution of 



potassic cyanide, gave, by gently evaporating the solution, 

 beautiful crystals of a double cyanide of davyum and 

 potassium. In this salt the potassium may be replaced 

 by several metallic elements. The cyanodavic acid is 

 very unstable ; it is isolated by passing a current of 

 sulphuretted hydrogen through a solution of the double 

 cyanide of lead and davyum. Sulphuretted hydrogen 

 produces, in the acid solutions of davyum, a precipitate 

 of sulphide of davyum, which is easily attacked by the 

 alkaline sulphides, yielding probably a series of sulpho 

 salts. 



A concentrated solution of chloride of davyum yields, 

 with potassic sulpho-cyanide, a red precipitate, and when 

 gently cooled, produces large red crystals. If the same 

 precipitate is calcined the sulpho-cyanide of davyum takes 

 the form of a black powder. These reactions show that 

 this salt is allotropic. 



W « 



120 T»» 160 ■•■'0 



,!.,,,l...,t,.i, l....l....ln,,ti.,ilniilMiil|ll 



Spectrum of davyum accordiug to the data of Sergius Kern, 



The chloride of davyum is very soluble in water, 

 alcohol, or ether ; the crystals of this salt are not deli- 

 quescent. The calcined salt gives the monoxide as a 

 residue. Chloride of davyum forms double salts with the 

 chlorides of potassium and ammonium. They are inso- 

 luble in water and very soluble in absolute alcohol. The 

 double salt of sodium and davyum is almost insoluble in 

 water and alcohol ; this reaction is very characteristic, 

 because many sodic salts of the platinum group are very 

 soluble in water. 



This chloride of davyum is the only one which exists, 

 as the second (product, containing more chlorine, is 

 decomposed during the evaporation of the solution, disen- 

 gaging chlorine. 



I have made some new researches on the density of 

 melted davyum ; three experiments gave the following 

 numbers :— 9,383 9,387, 9,392 at 24°. These results agree 

 very sensibly with those of my first researches ; the density 



of davyum given in my first note to the Academy being 

 9.385 at 25°. 



M. Alexejeff has undertaken the determination of the 

 equivalent of davyum ; but as the quantity of davyum 

 which I possess is very small, exact researches are diffi- 

 cult. Preliminary experiments have shown that the 

 equivalent is greater than ico, and probably about 150- 

 154. 



Some newplatiniferous sands, which are to be placed at 

 our disposal, will yield a sufficient quantity of the new 

 metal for additional experiments. We hope to have in 

 time nearly i'2 gr. of davyum. 



Finally I have investigated the spectrum of davyum by 

 vaporising the metal in powder between the carbons of 

 the electric lamp. The spectroscope at my disposal is 

 not powerful enough to show precisely all the secondary 

 lines. This is why I have only indicated the principal 

 lines easily visible in my spectroscope.' 



THE 



OF 



GREAT DETONATING METEOR 

 NOVEMBER 23, 1877 



HAVING fully discussed the whole of the accounts of 

 the great meteor that have reached me, consisting 

 of some ninety direct communications and forty or fifty 

 newspaper cuttings, I have the pleasure to forward to 

 Nature a condensed description of it. 



The points of most importance to be determined are — 

 I. The true orbit which is obtained from a knowledge of 

 the radiant and velocity of motion. 2. The height at 

 which it first became luminous, as our knowledge of the 

 real extent of the earth's atmosphere depends exclusively 

 upon such determinations. 3. The height at which it 

 exploded and came to an end. That this last is connected 

 with the physical condition and constitution of the body 

 cannot be doubted. The brightness of meteors seems 

 always to depend upon the distance they penetrate into 

 the air. Generally, when they get below 30 or 40 miles, 

 they are very remarkable. 



The Greenwich mean time was 8h. 24m. 30s. on 

 November 23. 



There are but few descriptions of, the path of the great 

 meteor in question from which to derive the radiant 

 point. Five of the fully-described tracks meet almost 



exactly in R.A. 62°, N.P.D, 69°. The others tend to 

 support this position rather than to alter it, but many are, 

 as is usual, extremely wild, passing 20°, and even 30° from 

 it. To an observer situated near the middle of the north 

 coast of Wales, this radiant would bear south 74° E., at 

 altitude 37°. 



The meteor first came visible to Mr. T. B. Barkas, at 

 Newcastle-on-Tyne, to another observer at Tynemouth, 

 to the Rev. G. Iliff, at Sunderland, and Mr. E. Pikard, at 

 York, at the great height of 96 statute miles. The 

 observers agree very closely. It is probable, of course, that 

 had any one been actually looking in the right direction, it 

 might have been seen a little earlier when it was still 

 higher. A height exceeding 90 miles is certain. The 

 meteor was then vertically over a point 13 miles north 

 of Derby, and its appearance was that of an ordinary 

 shooting star. Descending in the air at the inclination of 

 39° to the surface of the earth, when 48 miles exactly over 

 Liverpool, it became intensely brilliant, so suddenly, that 

 many observers speak of this as the first explosion. 



It was at this instant that it attracted universal atten- 

 tion. People as far distant as Essex, Roscommon, 

 Edinburgh, Bristol, and Queenstown, 200 miles from it, 



' Comptes Rendus and Chemical News. 



