April 24, 18S4J 



NATURE 



615 



were with hydrogen and oxygen, but on llie wliole there were as 

 many metallic lines photographed from the flashes of carbonic 

 oxide as from those of hydrogen. 



When the iron tube was lined with copper foil, only one copper 

 line in the visible spectrum, K 5105, was seen, and in the ultra- 

 violet two lines, A 3272 and A 3245 '5. All three lines were very 

 strong, and the two ultra-violet lines were in some cases reversed. 

 These lines were also frequently developed when no copper lining 

 was in the tube, probably from the brass of the small side 

 lubes. 



Copper also gave a line in the indigo, \ 42S1 about, decidedly 

 less refrangible than the copper line, \ 4275, coincident apparently 

 with the strong edge of one of the bands developed when a copper 

 salt is held in a Bunsen burner. 



A lining of copper which had been electro-plated with nickel 

 fleveloped only one nickel line, A 5476, in the visible part of the 

 s))ectrum, but gave by photography twenty-five lines in the ultra- 

 violet. 



When copper wire electro-plated with cobalt was put into the 

 tube twenty-two cobalt lines in the violet and beyond were 

 jihotographed. 



No other metal gave anything like the number of lines that 

 were given by iron, nickel, and cobalt. 



A lining of lead gave the lines A 405S, 36S3, and 3639 strongly, 

 and these lines were frequently developed, though less strongly, 

 when there was no lead lining ; the metal being without doubt 

 derived from the leaden washers used to make the ends of the 

 tube air-tight. 



A strip of silver gave the lines A 3381 '5 and 327S, and these 

 lines were sometimes reversed. No trace of the channelled 

 spectrum of silver was developed even when silver oxalate was 

 put into the tube, and furnished plenty of silver dust after the 

 first explosion. 



A magnesium wire about 2 millims. thick and two-thirds the 

 length of the tube gave the b lines very well ; that is to say b-^ and 

 b„ were well developed, and b^ was also seen, but as the iron and 

 magnesium components of b^ are very close together, and the 

 iron line had been observed before the introduction of the mag- 

 nesium, it was not possible to say with certainty whether or not 

 the magnesium line were present too. No other magnesium line 

 could be detected. The blue flame line was carefully looked for, 

 but could not be seen. The photographs showed none of the 

 rnagnesium triplets in the ultra-violet, nor any trace of the strong 

 line A 2852, which appears in the flame of burning magnesium, 

 and is yet more conspicuous in the arc when that metal is 

 jjresent. 



Metallic manganese, introduced into the tube in coarse powder, 

 gave the group at wave length about 4029 with much intensity, 

 but no other manganese line with certainty. In the visible part 

 of the spectrum the channellings in the green due to the oxide 

 were \'isible. 



A lining of zinc produced no zinc line, and zinc-dust gave only 

 a very doubtful photographic impression of the line A 3342. A 

 strip of cadmium gave no line of that metal either in the visible 

 or in the nltra-violet part of the spectrum. 



Tin, aluminium, bismuth, and antimony, also failed to produce 

 a line of any of those substances, and so did mercury which was 

 spread oyer copper foil made to line the tube. 



Thallium spread as amalgam over the copper lining gave the 

 lines A 3775-6, 3528-3 and 3517-8. 



Chromium was introduced as ammonium bichromate, which of 

 course left the oxide after the first explosion. This gave the chro- 

 mium lines with wave-lengths about 5208, 5205, 5204, 42S9, 

 4274'5. 4253'5- '»'«'■>' well and persistently, also the lines with 

 wave-lengths about 3605, 3592-5, 3578-5. 



Sodium salts (carbonate, chloride) developed the ultra-violet 

 line A 3301 ; and potassium salts give the pair of lines about wave- 

 length 3445 ; but no more refrangible line of either metal was 

 depicted on the photographs. Lithium carbonate gave, besides 

 the lines in the red, orange, green, and blue, the violet line, 

 ^ 4135 '5 ; '^u' no more refrangible line. 



Photographs of a flame of mixed coal-gas and oxygen, in which 

 an iron wire was burnt, show, as might be expected, the same 

 iron lines as are developed in the flash of the detonating gases, 

 and of the same relative intensities. These intensities are not 

 quite the same relatively as they are in the arc spectrum. Thus 

 the lines A 3S59, 3745, 3737, 3735, and 3719 come out in great 

 strength, much stronger than the lines A 3647, 3631, 3618, which I 

 arc remarkably strong in the arc. | 



German-silver wire, burnt in the flame of coal-gas and oxygen, ' 



gave the same nickel lines as were given by nickel in the de- 

 tonating gases, as well as those of copper and lead. 



Copper wire gave, besides the lines A 3272, 3245-5, a set of 

 bands in the blue, which correspond with those given by copper 

 salts in flames, and are probably due to the oxide. 



The greater part of the lines observed in the flames of the ex- 

 ploding gases have been observed by the authors to be reversed 

 when the several metals were introduced into the arc in a crucible 

 of lime or magnesia ; which is quite in accord with the supposi- 

 tion that the metals experimented on are volatile, and emit as 

 well as absorb these particular rays, at temperatures lower than 

 that of the arc. 



That iron is volatile at a temperature below the fusing point of 

 platinum, which is about 1700" C, has been pointed out by 

 Watts [Phil. Mag., vol. xlv. p. 86), who observed in the flame 

 of a Bessemer converter almost all the green and blue lines of 

 iron which we have seen in the exploding gases, besides one or 

 two lines which we have not observed or identified. Having 

 regard to this volatility of iron, it does not seem so surprising 

 that iron lines should be observed accompanying those of hydro- 

 gen to great heights in the sun's atmosphere as that they should 

 not be always seen there. 



Copeland (Copernicus, December, 1882) observed in the 

 spectrum of the great comet of 1882 four lines nearly identical 

 with four of the green lines of iron seen in the detonating gas. 



It is remarkable that such volatile metals as mercuiy, zinc, 

 and cadmium should give no lines in the flame of the exploding 

 gases. 



The absence of any metallic lines more refrangible than T in 

 the flame of the exploding gases may be in part due to a falling 

 off" in the sensibility of the photographic plates for light of shorter 

 wave-lengths ; but as the spark lines of iron seem to be quite as 

 strongly depicted on the plates in regions of the spectrum far 

 above T as they are in the regions below, want of sensitiveness 

 in the plates cannot be the only reason for the absence of 

 liigher lines, but probably the emissive power of the metals 

 for these lines is feeble at the comparatively low temperature 

 of the flame. 



Gouy [Comp. R., 1877, p. 232), using a modification of 

 Bunsen's burner fed with gas mixed with spray of metallic 

 salts, observed at the point of the inner green flame three or 

 four iron lilies which have not been observed in the flame of 

 the detonating gas, the lines b^ and b„ of magnesium, two 

 cobalt lines in the blue which are not seen in the detonating 

 gas, one line of zinc, and one of cadmium, and the two strong 

 green rays of silver. Can the appearance of these rays under 

 these circumstances imply that the temperature of the inner 

 green cone of a Bunsen burner, when the proportion of air to 

 coal-gas is near the exploding point, is higher than that of the 

 explosion of hydrogen and oxygen ? 



The interesting theoretical questions which are suggested by 

 the facts recorded in this paper the authors leave for further 

 discussion. 



Linnean Society, April 17.— Alfred W. Bennett, M. A., in the 

 chair. — Messrs. R. Lloyd Patterson and Benjamin Lomax were 

 elected Fellows. — Dr. J. Poland exhibited under the microscope 

 a series of preparations, stained by reagents, illustrating the 

 Bacillus of anthrax of man. He remarked on the severely fatal 

 character of the malady, not only in this country but on the 

 Continent and certain places abroad. The 5ar-;//aj--spores were 

 in many instances doubtless conveyed in the dried skins and 

 hides imported from abroad, and under favourable conditions 

 inoculated those handling the dried hides, &c., the germs deve- 

 veloping in the usual manner of the low vegetable organisms. 

 — Dr. R. C. A. Prior drew attention to specimens of Draba 

 aizoides obtained from Pennard Castle, Swansea, said to be 

 the only locality where this plant grows wild in England. — 

 The ninth contribution to the ornithology of New Guinea, 

 by Mr. R. Bowdler Sharpe, was read, and it dealt with 

 some few birds obtained by Mr. A. Goldie in the Astrolabe 

 Mountains. — A paper was read by the Rev. J. M. Crombie on 

 the algo-Iichen-fungal hypothesis. The author gave a brief 

 sketch of the hypothesis as enunciated by Schwendener, Bornet, 

 and others, noticing the various arguments and illustrations which 

 had been adduced in its support. He then discussed the result 

 which had been obtained from experiments in lichen-culture, 

 whether from the spore or by synthesis — observing that in both 

 cases these were confessedly but small, owing to the very great 

 difficulty of cultivating beyond a rudimentary stage except under 

 the same atmospherical conditions in which they grow in 



