could be recognized" (p. 442). M. Trouvelot says: "We knew already that great prominences show themselves quite frequently at the ends of the same diameter, and we even suspected that a relation existed between them; but as these objects often occupy quite a considerable extent upon the sun, it was difficult to determine whether their being met at diametrically opposite points was a simple coincidence, or whether they were in relation and obedient to a common cause. The observation of the 26th of June seems to be in favor of the last supposition." Secchi says: *"M. de la Rue has remarked that great spots are generally situated at the extremities of the same diameter. The same law also applies very often to the development of great prominences. This coincidence agrees well with the hypothesis of an action analogous to that which produces the tides." An examination of the longitudes of the planets on June 26, 1885, shows that Mercury and Saturn were nearly in line with the earth, but the tide-raising power of the combination does not seem great enough to produce such an extraordinary effect. as that of the gigantic prominences seen by Trouvelot. Evidences of Explosions within the Stars. As Ranyard has pointed out, instead of the doctrine that the stars are products of condensation from nebulae, could be equally well substituted the opposite one that the nebulae have been thrown out explosively from previously existing stars, without doing violence to the appearances; and it may be that both processes are real, and that a criterion for distinguishing between them should be sought. The curved streaks of nebulosity in the Pleiades appear to have some connection with the stars. The largest stars: Alcyone, Maia, Electra, and Merope, are in the midst of nebulae, and some of the streaks, especially those around Maio, have forms which at least are not inconsistent with the supposition that they may have emanated from the star at various times. Miss Clerket computes as a possible minimum value of the distance of the Pleiades, 1,500 billions of miles, or 250 lightyears. "An assemblage like the Pleiades distributed round our sun would extend compactly three-quarters of the way to a Centauri, its feelers and appendages indefinitely farther." + The brilliancy of the brighter stars in this case is several hun *Le Soleil, 2 ed., vol. 1, p. 192, Paris, 1875. Miss Agnes M. Clerke, The System of the Stars, p. 226. dred times that of our sun. Their masses may even now exceed the limit demanded by the explosion hypothesis. From some of the stars, nebulous arms proceed on opposite sides. Here the explosion has not been strong enough to blow the star to pieces; but more complex interlacing structures, and clusters of stars come either from successive explosions, or from a single one of such power as to produce disruption along a multitude of diverging paths. A sufficiently powerful explosion will give free wandering stars; and globular clusters, in this view, are relatively transient associations. The ultimate fate of aggregations formed in such a manner must be to break up. The star sprays and star drift noted by Mr. Proctor in his "Universe of Stars" may have resulted from such dispersals. The government of the heavens is like that of a great republic. No regal orb compels allegiance of a host of inferiors. The solar system is a family, where the relations of parent and child are recognized; but the stellar universe is a brotherhood, in which freedom and equality reign. This view distinctly traverses the conception which has prevailed hitherto: that star-clusters are agglomerations condensed by the attraction of gravitation. If this were so, those clusters in which the action has been going on longest should be the most highly condensed. Instead of this, we find the most open and least typical clusters, such as Coma Berenices, to be those which include the greatest variety of stellar spectra and the most advanced types. * The splitting of a star in two by a directed explosion at its center should, in general, originate two equal motions in opposite directions in the equatorial plane, for the reason that centrifugal force diminishes the pressure in this plane of which some particular diameter is liable to form a line of least resistance. As the outer layers are not concerned in the explosion, they remain at rest and constitute inert envelopes which will be dragged along by the moving parts, retarding them and perhaps at last destroying their motion by friction. The result will be a pulling out of the material of the star into finger-like extensions whose form, persistent through the partial or perhaps complete destruction of relative motion, will depend upon the relative velocities of the original rotation and proper motion, combined with the varying velocity due to the explosion, as the motion is gradually overcome by friction. Except in the rare case of a star without proper motion, or of one whose proper motion is in the equatorial plane, the *Compare E. C. Pickering aided by M. Fleming, "Miscellaneous Investigations of the Henry Draper Memorial," Ann. Harvard Coll. Obs., vol. xxxvi, part 2, Table 29. p 283, 1897. resulting double spiral or sigmoid curve of the combined trajectories cannot lie in one plane. Moreover, the two arms will not be entirely symmetrical, but both will lie on that side of an equatorial plane through the origin of motion towards which the direction of proper motion points, and unless the proper motion is directed at right angles to the original equatorial plane, the two branches will have different curves. Figures of this sort have been found by Holden* from a comparison of a considerable number of spiral nebulae, and Keeler's crowning work with the Crossley reflector indicates that the number of spiral nebulae is very large. Friction during the transformation must largely overcome the original rotation. Any remnant of rotary motion is probably confined to the original nucleus or to nuclei at the tips of the horns. In the absence of original rotation or proper motion, the result of an explosion will be a straight nebulous ray, which may retain a central nucleus and two subordinate ones symmetrically disposed in the tips. Many other varieties will suggest themselves. The stars Asterope (Wolf No. 121), mag. 65; Wolf No. 129, mag. 70, and Wolf No. 182, mag. 75 in the Pleiades, terminating curved nebulous streamers from Maia, mag. 45, may serve as an example. The existence of a few "run-away stars, with velocities much exceeding those which gravitation can produce, suggests that under rare circumstances explosions may occur through a large part of a stellar volume, so that the remnant thrown off is not much retarded by the resistance of outer inert layers. *E. S. Holden, "On the Helical Nebulae." Pub. Astr. Soc. of the Pacific, vol. i, p. 25, 1889. [To be continued.] SCIENTIFIC INTELLIGENCE. I. CHEMISTRY AND PHYSICS. 1. Chemical Reactions Produced by Radium.-BERTHELOT has made a series of experiments upon the chemical action of the rays emitted from a small sample of radium chloride (about 0·1g.), which had been obtained from M. Curie. The active salt was contained in a small hermetically sealed glass tube, and for the purposes of experiment this tube was enclosed in a second tube, so that the rays were obliged to traverse two glass walls where the substance to be experimented upon was in contact with the outer tube, while three layers of glass were interposed when the radium acted from without a vessel containing the substance. It is possible, if radium rays vary as light rays do, that a part of the active rays may have been intercepted by the glass. The experiments were performed in the dark, with the use of parallel experiments without radium for comparison. It was found that solid iodine pentoxide was decomposed by the radium rays, as by light, into iodine and oxygen, while concentrated nitric acid, in the same manner, became yellow. These two reactions are endothermic, hence it is shown that the rays supply chemical energy. On the other hand, it was shown that several exothermic reactions were not produced by the rays. The conversion of rhombic sulphur in carbon disulphide solution into insoluble sulphur, which is caused by the action of light and is slightly exothermic, was not produced by the radium rays. The exothermic polymerization of acetylene gas, which is induced by electric effluvia, but not by light, was not effected by the radium. Oxalic acid, which is oxidized by atmospheric oxygen even in diffused light, did not undergo this oxidation under the influence of the radium rays. It was found further, as had been previously noticed, that the glass in which the sample was contained was blackened, evidently from the reduction of lead, while near the blackened regions a violet tint, probably due to the oxidation of manganese, was observed.- Comptes Rendus, exxxiii, 659. Soon after the appearance of Berthelot's article, which has been noticed above, BECQUEREL published a note upon the same subject. Attention is there called to the fact that salts of barium containing radium are spontaneously phosphorescent, so that in making experiments with them the phosporescent light should be cut off by the use of black paper or a thin sheet of aluminum foil. He observes that the production of ozone by radium rays, which has been noticed by M. and Mme. Curie, is an endothermic action analogous to those observed by Berthelot. The chemical action of the rays in their photographic behavior is recalled, as well as their strong coloring action on glass, porcelain, paper, rock-salt and sylvine, their alteration of barium platinocyanide, and their destructive action upon the skin. He mentions two exothermic reactions that have not been previously noticed the conversion of white phosphorus into the red modification, and the reduction of mercuric chloride to mercurous chloride in the presence of oxalic acid in solution. He mentions finally the interesting fact, recently observed in his laboratory, that seeds exposed to radium rays for a long time before planting do not germinate. This action is slow, for little effect is noticed after 24 hours, but it is effective after a week or more.- Comptes Rendus, exxxiii, 709. H. L. W. 2. The Preparation of Nitrogen from Ammonium Nitrate.— In attempting to prepare nitrous oxide, N,O, by the decomposition of ammonium nitrate, the plan of heating this salt with a high-boiling solvent suggested itself to J. MAL. Upon using glycerine for this purpose (50g. glycerine with 25g. ammonium nitrate), and heating to 190°, a gas began to be given off, and this continued without further heating until the temperature fell to 150°. After this a regular stream of gas could be obtained by heating to 160° or 170°. It was found that the addition of a few drops of concentrated sulphuric acid to the original mixture lowered the temperature at which the gas came off at first. Upon examining the gas it was found to be nearly pure nitrogen instead of the expected nitrous oxide, and it was shown that oxidation of the glycerine to glyceric acid had taken place. It is possible that the method may be useful in preparing nitrogen on the large scale, and it may be expected that the method of oxidizing organic substances will be useful in other cases besides that of glycerine. -Berichte, xxxiv, 3805. H. L. W. 3. The Atomic Weight of Tellurium.-According to the position of tellurium in the periodic system of the elements its atomic weight should be less than that of iodine, but the most reliable determinations that have been made in the past have given results which indicate an atomic weight somewhat above 127, while that of iodine is considered to be 126.85 (oxygen being taken as 16). PELLINI has recently made some new determinations of the atomic weight, using tellurium which had been purified by the recrystallization of diphenyl-tellurium-dibromide, and by distilling the elementary substance in a vacuum. determinations were carried out by converting weighed quantities of tellurium into the dioxide and weighing the latter, and also by the reverse of this operation. Fairly satisfactory agreements were obtained, and the average of the results indicates an atomic weight of 1276, which is in close accordance with the value found by several other investigators.-Berichte, xxxiv, 3807. The H. L. W. 4. Artificial Spinel.-Although this mineral has been prepared artificially by several chemists, it is interesting to notice that DUFAU has found a very simple method of forming it by means of the electric furnace. An intimate and well calcined mixture of 200g. of alumina and 100g. of magnesia is heated in a |