Nov. 2 2, 1883] 



NATURE 



89 



mcnts prior to the great perturbalion in this year are determined, 

 and have been aheady transcribed in Nature ; they present a 

 resemblance to those of the first comet which appeared in 1798, 

 about which year lirorsen's comet might have been in perihelion ; 

 Dr. Harzer nevertheless expresses the opinion that, although 

 Messier's observations of the comet of 1798 might be open to 

 some degree of uncertainty, it is doubtful wliether they would 

 admit of being represented by an elliptical orbit with a short 

 period. He had found the revolution prior to 1842 to be 5'I70 

 years. 



The N.A.UTICAL Almanac. — The volume of this ephemeris 

 for 1887 has been published during the past week, the contents 

 being generally the same as in previous years. The (rack of the 

 total solar eclipse of August 19 is given in detail for the greater 

 part of the course, and the maximum duration of totality is found 

 to be 3m. 50s., the central eclipse with the sun on the meridian 

 falling in longitude 102° o' E. and latitude 53° 47' N. The 

 Greenwich list includes four occultations of AhUbaran during 

 the year and one of Rfguhis. , 



The average annual .'ale of the A'aa/zVa/ .<4//«a«<7c during the 

 last five years has exceeded 15,500, though many maritime 

 nations have now their nautical ephemeris. 



THE PHILOSOPHICAL SOCIETY OF 

 GLASGOW 

 'n"'HE Procccdiiti^s for 1882-83, pp. 592, 23 plates, and 3 maps, 

 have just been issued, and contain the following papers : — 

 On insensibility arising from a deficiency of oxygen in the air, 

 by Dr. Wallace, president ; on technical education, by David 

 Sandeman and E. M. Dixon, B.Sc. ; on the deciy of building 

 stones, by Dr. Wallace ; on some new infusoria, by William 

 Milne, M.A. ; note on Lippmann's capillary electrometer, by 

 Dr. McKendrick ; on milk and milk pollution, by Dr. John 

 Dougall ; on Struther's process for pulverising diamondiferou^ 

 ore, by Wall.-ice Fairweather, C.E. ; on the use of litmus, methyl 

 orange, phenacetolin, and phenolphthalein as indicators, by R. 

 S. Thomson ; on approximative photometric mea'Urements of 

 sun, moon, cloudy sky, and electric and other artificial light-, 

 by Sir William Thomson ; on the preservation of food by cold, 

 by ]. J. Coleman ; on the clauses in the Glasgow Police Bill 

 having reference to the prevention and mitigation of disease, by 

 Dr. Ebenezer Duncan ; on the ships and shipping trade of Great 

 Britain, by N. Dunlop ; on the iron ore industry of the north of 

 Spain, by J. J. Jenkins ; on the use of rosolic acid as an indi- 

 cator, with additional notes on phenolphthalein and methyl 

 orange, by R. S, Thomson ; on architecture in Glasgow, by jf. 

 Sellars, jun., I. A. ; on the water h-ghways of the interior of 

 Africa, with notes on slave hunting and the means of its sup- 

 pression, by James Stevenson, F. R.G.S. ; on a new seismo- 

 graph, by Thomas Gray, B.Sc. ; on the fertilisation of flowers, 

 by Rev. A. S. Wilson, M.A. ; on algin, a substance obtained 

 from ;ome of the commoner species of marine algas, by E. C. C. 

 Stanford; on chemical industries, by K. R. Tatlock ; on nitro- 

 glycerine, dynamite, and blasting gelatine, by George McRoberts, 

 manager of the Works of Nobel's Explosives Company ; on the 

 action of heat and the chlo. ides of phosphorus upon the water 

 ^alts of hypophosphorus, phosphorus, and phosphoric acids, by 

 Dr. Otto Richter ; on a volumetric process for the estimation of 

 cobalt and nickel, by Dr. John Clark ; and, on the development 

 and generic relations of the corals of the carboniferous system of 

 Scotland, by James Thomson, F.G.S. 



The society has at present 19 honorary, 10 corresponding, and 

 nearly 700 ordinary members, and is about to enter on its eighty- 

 fir,-t session. In addition to the ordinary meetings of the society, 

 held fortnightly, there are sections fcr architecture, biology, 

 chemistry, sanitary science and social economics, and geography 

 and ethnology. 



RESEARCHES ON SPARK SPECIRA 



The Disappearance of Short Lines 



I T was shown in a former Report of this Committee (Southampton 



meeting) that the spectra of metallic solutions wtre the same 



as tho;e from metallic electrodes line for line, even short and 



weak hnes being reproduced. The principal difference ofcerv- 



' Report o£ the Comnjiltee en the Compaiifion of the Srark Specira of 

 the Elements w.th Spectra of Sclulions of their Compounds, drawn up by 

 Prof. W. N. Hartley. 



able in the two spectra was a lengthening of the short lines when 

 spectra were taken fiom solutions, so that discontinuous lines 

 became long or continuous lines. A few instances of short lints 

 disappearing have also been noticed, but such disappearances 

 occur only w hen the lines are so short, mere dots, in fact, that 

 no solution can contain a quantity of the metal sufficient to 

 yield an image of them. Certain very short lines in the spec- 

 trum of metallic zinc are an example of this. Very short lines 

 in the spectrum of alumii.ium were not reproduced by solutions 

 of the chlorides except when the solutions were very str< ng, and 

 then they always appeared. It may thus be seen that the quan- 

 tity of metal present in the compound determines the presence 

 of these lines. 



The Lengthening of Short Lines. — It was remarked that in 

 certain cases metallic electrodes showed a different spectrum 

 according to whether the spark was passed between dry or wet 

 electrodes. Thus it was pointed out that when iridium elec- 

 trodes are moistened with calcic chloride, discontinuous lines 

 which are very nunierous in this spectrum become continuous; 

 and on further examination into this matter it has been found 

 that even moistening with water has the same effect. Hence 

 the supposition, of which there seemed some possibility but no 

 proof, that a chloride of the metal was formed is found to be 

 untenable. The very short lines in the spectrum of zinc were 

 lengthened by the action of water upon the electrodes. It has 

 LOW been proved beyond doubt that this peculiar variation in 

 the spectra is caused by the cooling action of the water upon 

 the negative electrode, which in effect is the same as a strength- 

 ening of the spark, since by heating the electrodes a reverse 

 action is the result. 



Alterations in the Spectrum of Carbon. — As already stated in 

 the previous Reports, graphite electrodes have been generally 

 employed for the production of spark spectra fr im solutions. A 

 portion of the work in connection with this subject included an 

 investigation of the effect of water and of saline solutions in 

 varying the spectrum of carbon. It will of c mrse be readily 

 understood that as carbon is capable of combining with oxygen 

 and nitrogen, that different spectra might be o itained by making 

 one or other of these gases the atmosphere suriounding the 

 electrodes, but it is not so easy to explain why graphite points 

 should give two different .'pectra in air when dry, and a third 

 spectrum, again different, when moist, the same spark conditions 

 being maintained. 



Three .'Uch spectra have been photographed, but without the 

 aid of maps thtir peculiarities are not capable of exact descrip- 

 tion. The maps which were drawn were presented 10 the Royal 

 Society, together with a communication on this subject, three 

 months since, so that they are not at present available. It may 

 be said, however, that the difference between the two spectra 

 taken from dry electrodes in air consists of the omission of a 

 certain number of the less refrangible lines, which lines have 

 undoubtedly been identified with carbon. 



Spectra of the NonMctallic Constituents of Salts. — A long 

 series of experiments has been made with the object of deter- 

 mining the non-mctallx elements which are capable of yielding 

 spark .spectra when in com ination with the metals. Fluorides, 

 chlorides, bromides, iodides, .sulphides, nitrates, sulphates, 

 selenates, phosphates, carbonate-, and cyanides yield nothing. 

 On the other hand, hydrochloric acid solutions nf arsenites and 

 antimoniates yield the spectra of arsenic and antimony. Borates 

 and silicates in solution yield very characteristic spectra of the 

 non-metallic constituents, but if the solutions be prepared from 

 sodium salts the lines of the metal do not appear in the case of 

 borates, and only the strongest sodium line 1^ = 3301) can be 

 observed in the sptctra of silicates, even when concentrated 

 solutions are u^ed. 



Line Spectra 

 DoKON Silicon 



SVave-ltnglhs Wave-lengths 



3450-1 2S8fO 



2497-0 2631-4 



2496-2 2541-0 



252S-I 



2523'S 



2518-5 



251S5 

 25137 

 2506-3 



24355 

 These are the first spectra of boron and silicon obtained from 

 metallic salts. 



