June 30, 1 881] 



NATURE 



207 



iron lines about the solar lines L and M, four strong lines below 

 N, the line O, all the strong lines frojn So to U inclusive, and 

 two strong groups still more refrangible. 



Potassium ferrocyanide introduced into the arc instead of 

 magne-ium gives a reversal of the same lines as are mentioned 

 in the foregoing paragraph. 



Iron wire fed in through a perforated pole gives reversals of 

 the highest grouo (wave-length 2492 to 2480), but with the lines 

 so much expanded as to form broad absorption-bands instead of 

 lines. 



With a vertical arrangement of the carbons and a stout iron 

 ■wire in the axis of the lower (positive) carbon, many more lines 

 in the visible part of the spectrum are seen expanded and re- 

 versed. This effect is sometimes enhanced by leading into the 

 crucible through the upper carbons, which is perforated for the 

 purpose, a very gentle stream of hydrogen gas ; the stream must 

 be no more than is just sufficient to give a tiny flame at the 

 the mouth of the crucible ; a stronger stream diminishes the 

 amount of metallic vapour, probably by its cooling action, and 

 lessens the effect. By this treatment some of the strongest line^ 

 of iron remain reversed for some time, the weaker lines are seen 

 to expand and be reversed for a few seconds at a time, when, 

 from a change in the intensity of the current, or some other 

 reason, a larger auount of metal is volatilised and sho.\s itself 

 by burning in brilliant scintillations at the mouth of the crucible. 



A list of the iron lines reversed, 136 in number, designated 

 by their approximate wave-lengths, is given in the paper. 



When the perforation of the lower carbon is filled with 

 titanium cyanide instead of the iron wire the titanium lines come 

 out very brilliantly and steadily, and many of them, especially 

 in the green and blue parts of the spectrum, are expanded and 

 reversed. A list of twenty-nine lines observed to be reversed is 

 given in the paper. 



In the case of chromium, introduced into the crucible either 

 as oxide or as bichromate of ammonia, there were no reversals 

 until a gentle current of hydrogen or of coal gas was led in 

 through the perforated carbon. This brought out the triplet in 

 the green, wave-lengths 5207, 5205, 5203, sharply and steadily 

 reversed, and likewise the three strong lines in the indijo, wave- 

 lengths 4289, 4274, 4253 ; also a triplet near N at wave-lengths 

 about 3578, 3593, 3606, apparently coincident with strong lines 

 in Cornu's map of that part of the solar spectrum, and a rather 

 strong double line just below O at about wave-length 3446. The 

 reversal of another chromium line at about wave-length 3217 is 

 doubtful. A triplet at wave-lengths 2799 '8, 2797, 2794, is more 

 easily reversed than any other of the chromium lines. This 

 triplet is generally strongly developed whenever a compound of 

 chromium is introduced into the cnjcible, so that the authors 

 conclude that it is due to that metal, but it is sometimes visible 

 in the photographs when other chromium lines are not seen. A 

 still more refrangible chromium line, wave-length about 2779 '6, 

 is also frequently reversed by a gentle current of hydrogen. 



The two aluminium lines near S are frequently reversed when 

 a fragment of the metal is dropped into the crucible, the less 

 refrangible line, wave-length 3091-5, being more strongly 

 reversed, and continuing reversed for a longer time than that at 

 wave-lengtli 3oSo'5. 



Cheinical Society, July 16. — Prof. Roscoe, president, in 

 the chair. — The following papers were read : — On the isomeric 

 acids obtained from coumarin and the ethers of salicylic alde- 

 hyde, by W. H. Perkin. The author has studied the action 

 of various agents on these bodies. The o body (from coumarin) 

 is converted into the ;8 body by heat or light. In general the 

 effect of chemical action on the a acid is to convert it into the 

 same compound as that yielded by the /3 body. Bromine forms 

 an exception, and two isomeric dibromides were obtained. The 

 author concludes that as the a body has a lower boiling-point, 

 density, refractive index, and is less stable than the /3 acid, it is 

 probable that its molecules are farther apart and that the 

 difference of distance is probably between the radical and the 

 hydroxy!. The derivatives from propionic and butyric coumarin 

 were studied. — Notes^on naphthalene derivative, by H. E. Arm- 

 strong and G. Lowe. The authors have continued their investi- 

 gations as to the action of sulphuric acid on naphthalene, and 

 confirm their previous statement that three and not two disul- 

 I>honic acids may be obtained. An isomeric & naphtholsulphonic 

 acid was prepared by dissolving fl naphthol in cold concentrated 

 sulphuric acid. — On the synthesis of ammonia, by G. S. Johnson. 

 The author reasserts that pure nitrogen, free from nitric o.xide, 

 when passed with hydrogen over spongy platinum, forms 



ammonia. If however the nitrogen be previously passed through 

 red hot asbestos no ammonia is formed. This indicates the 

 existence of an active allotropic nitrogen analogous to ozone. — 

 On the alkaloids of nux vomica, by W. A. Shenstone. Tlie 

 author has prepared pure brucine, but concludes that the so- 

 called Igasurin has no existence. — Notes on photographs of the 

 ultra-violet emission spectra of certain elements, by W. N. 

 Hartley. — On the sulphates of aluminium, by S. U. Pickering. 

 — On two new oxides of bismuth, Ijy M. M. P. Muir, BLjO, and 

 Bi407, prepared by the action of aqueous potassium cyanide on 

 a hot nitric acid solution of bismuth nitrate. 



Royal Microscopical Society, June 8. — The president. 

 Prof. P. Martin Duncan, F. R.S., injthe chair. — Eleven new 

 Fellows were elected and proposed. — Prof. Paul Reinsch 

 attended the meeting and exhibited specimens of the vegetable 

 forms found by him in the Coal measures. — The president read 

 a paper on some remarkable enlargements of the axial canal in 

 sponge spicula and their causes, accompanied by drawings on 

 the blackboard. Nearly all the spicula obtained from specimens 

 of very deep soundings off Japan were found to have the normal 

 axial canal enlarged in a moniliform or conoidal manner, pro- 

 ducing very elegant results. The spicula were of seven or eight 

 kind.s, and were mature. The enlargement was found to be 

 invariably accompanied by an open condition of the axial caml 

 or by penetrations, cylindrical in outline, from without, down to 

 the canal. The penetrations were shown to be connected with 

 an organic body resembling the zoospores of an Achlya^ and 

 granules, organic in nature, were observed mthin the enlarged 

 canals. Thinning and solution of the spicula, the result of these 

 organisms, were considered, and admitting the influence of great 

 pressure, the president stated that he had mever seen anything 

 which led him to believe that there was free carbonic acid gas in 

 the ocean. — A note was read by Dr. Savage calling attention to 

 the changes which took place in nervous tissues in the process 

 of hardening. — Mr. Holmes read a paper on a new British Algj, 

 specimens of which were exhibited. — Discussions also took place 

 on the value of swinging sub-stages on the motion of diatoms. — 

 Dr. Maddox exhibited some micro-photographs of diatoms, and 

 Mr. Powell demonstrated the aperture of his |-inch oil-immersion 

 objective = I '47 num. ap., the largest hitherto made. 



Physical Society, June 25. — Prof. Fuller in the chair. — 

 Senor Olympio de Barcelos was elected a member. — Mr. Grant 

 exhibited an apparatus for showing the position and direction of 

 the curve of zero electro-dynamic induction. It consisted of two 

 coils of insulated wire mounted on stands, one being fixed while 

 the other was free to rev jlve round it at a fixed distance. — Prof. 

 W. E. Ayrton explained the determination of the refractive 

 index of ebonite made by himself and Prof. Perry. The result 

 for oxy-hydrogen light was I '7, but at the suggestion of Prof. 

 Fitzgerald of Dublin this was checked by measuring the polarising 

 angle of ebonite by reflected light. Sunlight was employed in 

 these experiments, and different pieces of ebonite. The result was 

 l'6ll. Professors Ayrton and Perry had repeated their former 

 experiments, using the electric light and a battery of 70 volts 

 E.M.F. The result confirmed the one first obtained. They 

 had also determined the index of refraction in the ordinary way 

 from the red rays, which they observed to pass through the prism 

 of ebonite. Result for the least refrangible rays r66. Mr. 

 Boys remarked that one could see better through thin ebonite if 

 it was varnished or wetted than when untreatod. — A letter was 

 read by the chairman from a sub-committee of the British 

 Association inviting the members of the Society to send exhibits 

 to the jubilee meeting of the British Association at York. 

 — Dr. Jimes Moser read a paper on the microphonic 

 action of selenium cells, in which he argued that the action 

 of the selenium cell in the photophone was that of a 

 microphonic contact or bad joint between the metal elec- 

 trodes or metal plates of the cell and the selenium. The 

 heat rays of the photophonic beam caused the joint 1 1 expand 

 and contract ; hence the variation in the current passing through 

 the receiving telephone. Dr. Moser also exhibited a piece of 

 selenium which increased, not diminished, in electric resistance 

 when light fell upon it. He further showed a standard Daniell 

 cell of the gravity type, which consisted of a glass vessel con- 

 taining the copper plate at the bottom immersed in sulphate of 

 copper solution, and the zinc plate at the top immersed in 

 sulphate of zinc solution, and a clear line of demarcation between 

 these solutions was produced by suspending an independent 

 piece of zinc midway between the plates, so as to decompose all 

 the sulphate of copper which diffused upward to that point. 



