442 



NATURE 



[March 8, 1894 



" At a few minutes past seven o'clock a bright cone of light was 

 seen springing up from the horizon at about east by north, this 

 was followed by detached cloud-like streamers, which gradually 

 joined into one vasl, wide arch of brilliant light, extending, for 

 a short time, completely across the heavens, slightly to the 

 south of the zenith, to the south-west by south horizon. Other 

 luminous patches also appeared on either side of this arch, one 

 covered the space around Jupiter, others the constellations of 

 Orion, Ursa Major, and Leo. Sometimes the rays or streamers 

 gradually brightened, at other times they suddenly flashed into 

 brightness ; the effect of this pulsating light was very beautiful. 

 The light was white, fading away at the edges of the rays, and 

 was very similar to a strong, distant light seen through a haze 

 or fog, which diffused the light, and softened its outlines. At 

 half-past eight o'clock the rays had disappeared, and were fol- 

 lowed by an arch of glowing light, which was centred at about the 

 north-rorth-west, rising about fifty degrees towards the zenith." 



M>. Fowler, and other observers at the Astrophysical 

 Laboratory, South Kensington, noticed a number of peculiarly 

 bright clouds, flashing out chiefly in the west and south-west, 

 between 7 and 8 p.m. He says : "From 8 p.m. to a little 

 after 9 the phenomena observed were confined to the north, 

 and took the form of a fine display of the aurora borealis. 

 Streamers were comparatively rare, but at half-past eight there 

 was a brilliant arc, reaching some ten degrees above the horizon 

 at the highest point, which was in or very near to the 

 magnetic meridian. Spectroscopic observations of the luminous 

 clouds showed that the light consisted mainly of that 

 which is characteristic of the aurora, being almost per- 

 fectly monochromatic and near wave-length 557. No 

 clouds were seen when the aurora was brightest. During 

 the maximum display of the aurora the characteristic bright 

 line of the spectrum was seen in nearly every part of the sky, 

 even where there was no visible haze or cloud." At the time of 

 observation Mr. Fowler thought that the clouds did not owe their 

 brightness simply to reflected aurora light, but as the observa- 

 tions towards the north were vitiated by the glare of the light of 

 the Imperial Institute, he thinks that he may have been misled. 



Rear- Admiral J. P. Maclear observed the aurora at Cranleigh, 

 Surrey. The following is an extract from his description of the 

 appearance presented: — "After sunset two white luminous 

 clouds, like bright fog clouds, became apparent in a west north- 

 west direction, and as darkness came on the northern horizon 

 was lighted with a pale green light. At 8h. 45m. there was 

 a rose-tinted patch like a cloud near the tail of the Great Bear, 

 at the same time the low arch of light to the northward was 

 bordered with a very faint rose tinge. At gh. the light gradu- 

 ally faded away." 



MiRA Ceti. — Observations of this variable star have shown 

 that it has continued to brighten since the predicted date of 

 maximum (February 17). At the present time (March 4) it is a 

 trifle brighter than 5 Ceti, a star of magnitude 4'2, and is quite 

 a conspicuous naked-eye star for a little while after darkness 

 sets in. There are no indications that it has even yet reached 

 the maximum. On some previous occasions it has reached the 

 second magnitude. The predicted date of maximum was no 

 doubt calculated on the basis of the period of 333 days, deduced 

 by Argelander, but it is well known that the period, like the 

 maximum brightness, is not always the same. There is evidence 

 of a regular irregularity to the extent of twenty-five days. The 

 present apparition is anything but favourable, owing to the 

 proximity of the star to the sun. 



According to the meteoritic hypothesis, the general light 

 changes in such a variable as Mira are produced by the revolu- 

 tion of a subsidiary swarm of meteorites round a larger central 

 one, the maximum luminosity occurring at periastron, when the 

 collisions are most numerous. A perfectly constant period, 

 however, can only occur in the case where the central swarm 

 has a regular figure and density. In swarms such as we see in 

 the spiral nebulae, taking rotation into account, it is evident that 

 the secondary swarm might reach periastron under very different 

 conditions in successive revolutions, and the maximum luminosity 

 might either precede or follow the periastron passage. 



Halley's Comet. — Prof. Glasenapp announces that the 

 computing bureau established by the Russian Astronomical 

 Society has undertaken the calculation of the true path of 

 Halley's Comet with a view to predicting the exact date of the 

 next return. He hopes that astronomers acquainted with un- 

 published observations of the comet will communicate the infor- 

 mation to the Society. 



NO. 1271, VOL. 49] 



IODINE AS A BASE FORMING ELEMENT. 



A N important memoir is contributed to the current issue of 

 ■^ the Berichte of the German Chemical Society, by Prof. 

 Victor Meyer and Dr. Hartmann. A new substance of a some- 

 what surprising nature, the first member in all probability of an 

 extensive series, has been prepared by them in the Heidelberg 

 laboratory. We have been so impressed with the strongly- 

 marked negative or acid-forming character usually exhibited by 

 the halogen elements, that it is more or less astonishing to learn 

 that a compound has been obtained containing iodine as the 

 central, predominating, or grouping element, which not only 

 contains that element acting in a tri-valent capacity exactly like 

 nitrogen in ammonia, but which is a powerful base, combining 

 with acids to form well-defined salts with elimination of water 

 precisely as when a caustic alkali is neutralised by an acid. 

 This remarkable new iodine compound is derived from an 



as yet unisolated base I.— H , similarly constituted to hydroxyl- 

 \0H 



The substance itself is represented by the 



amine N^H . 

 \OH 



/CgHs 

 formula I^-C(iH4l, and just before transmitting the manuscript for 



\OH 

 publication, the information was appended that the pure di- 



/QHg 



phenyl derivative I^CgHg had likewise been isolated, but fur- 



\OH 

 ther particulars of it were reserved for a subsequent com- 

 munication. 



Prof Meyer was led to suspect the possibility of the existence 

 of such a compound from the fact that the oxy-iodine derivative 

 of benzoic acid, the so-called iodoso-benzoic acid, 



CgHj (10) (COOH), 

 exhibits a very much feebler acid character than ordinary iodo- 

 benzoic acid, CgHjI . COOH, and partakes indeed more of the 

 character of a phenol, indicating that the group .1:0 is en- 

 dowed with basic instead of acid properties. This supposition, 

 moreover, is confirmed by the remarkable observation of Will- 

 gerodt, who has shown that the analogous derivative of the 

 hydrocarbon benzene itself, iodoso-benzene CgH, . 10, forms a 

 series of well-defined salts with acids. Hence it would appear 

 that the as yet unisolated compound H . I : O cannot be called 

 hypo-iodous acid, for it is apparently a basic substance, and not 

 an acid at all. An attempt was therefore made to saponify 

 iodosobenzeneby boiling it with dilute sulphuric acid, in order to 

 convert it, if possible, into phenol and the sulphate of the sup- 

 posed base. Dilute sulphuric acid readily dissolves iodoso- 

 benzene with formation of a sulphate, as shown by Willgerodt, 

 but on mere boiling it still exhibits the reactions of iodoso- 

 benzene. Upon evaporation of the solution, and warming for 

 several hours over the water-bath, however, it loses its capability 

 of liberating iodine from potassium iodide, and a sulphate of a 

 basic substance is indeed found to have been produced. As a 

 method of preparation, however, the following is a much more 

 convenient process : — 



The iodosobenzene is placed directly in the calculated quantity 

 of strongly cooled concentrated sulphuric acid. The solution 

 becomes coloured brown, and contains no trace of the original 

 iodosobenzene, as evidenced by its inability to liberate iodine ; 

 it consists almost entirely of the sulphate of the new base. The 

 liquid is diluted by adding pieces of ice to prevent loss by rise 

 of temperature, and the solution is most advantageously used to 

 prepare the insoluble halogen salts, which much resemble those 

 of silver, lead, and thallium, by adding a solution of potassium 

 or sodium chloride, bromide, or iodide. 



The free base is best obtained from the precipitated iodide 

 by agitation with moist silver oxide. It may also be obtained 

 directly from the sulphate by addition of baryta water ; the 

 solution thus obtained, however, is much more dilute. The 

 aqueous solution of the base reacts very strongly alkaline. It 

 cannot be readily obtained an the anhydrous condition, as it 

 concentrates to a thick gum. Analyses of the iodide indicate 

 that the empirical formula of the salt is C4H3I. Upon dry dis- 

 tillation the iodide decomposes completely to mono- and di- 

 iodobenzene ; hence its molecular formula must be_,three times 

 the empirical, or CJ2H9I3. 



C12H9I3 = CgHgl 4- C6H4I2. 



