May 24, 1894] 



NA TURE 



87 



imentwith 4'i grams of a 52 per cent, solution of hydroxylamine, 

 I 10 grains of methyl iodide (the molecular proportion), and a 

 i smaller quantity of methyl alcohol, mixed together in a flask 

 I filled with an upright condenser, the energy of the reaction was 

 found to be sufficiently great to heat the liquid to the point of 

 I ebullition, and crystals soon commenced to deposit. Ethyl 

 , iodide reacted in a precisely similar manner. The crystals, 

 after draining and washing with a mixture of alcohol and elher, 

 I proved to be those of the pure hydriodides of the /3-alkyl 

 hydroxylamines. Their aqueous solutions acidulated with 

 1 nitric acid do not reduce silver nitrate, so that their analysis is 

 easily effected. In this respect they differ from nitric acid 

 'solutions of hydroxylamine, which of course at once reduce 

 I silver nitrate. They reduce Fehling's solution, however, in- 

 stantly at the ordinary temperature. It would appear from this 

 mode of preparation that the action of alkyl iodides on hydroxyl- 

 amine is similar to their action upon ammonia. The salts are 

 perfectly stable up to beyond 200' C. M. de Bruyn shows 

 finally that it is not essential to have at command such concen 

 trated solutions of hydroxylamine as those obtained during the 

 preparation of the solid base. The weak aqueous or alcoholic 

 solutions obtained in the usual manner from hydroxylamine 

 hydrochloride, may equally well be employed ; it is only neces- 

 sary to decompose the solution of the hydrochloride in tepid 

 water with potash, add an equal bulk of methyl alcohol, filter 

 from the precipitated potassium chloride, and at once proceed 

 to agitate with methyl iodide. The only further point of 

 difference is that the liquid should be finally lulled in the flask 

 fitted with upright condenser in order to complete the reaction. 



The additions to the Zoological Saciety's Gardens during 

 the past week include a Black-eared Marmoset {Hapah 

 fcniciliata) from South-east Brazil, presented by Mr. H. M. 

 Dodington ; a Common Peafowl {Pavo crislalus) from India, 

 presented by Mrs. Tannenbaum ; a Monteiro's Galago {Gti/n^v 

 monleiri) from West Africa, two Pinche Monkeys {Miuat 

 fdipus) from New Granada, deposited ; a .Maholi Galago 

 (Galago maholi), two Japanese Deer \ficrvHi sika) born in the 

 Gardens. 



OUR ASTRONOMICAL COLUMN. 



Recent Okservations of Jupiter's Satellites. — In 

 the May number of Aslronomy and Aslio-I'/tysies, Dr. E. S. 

 Uolden calls attention to some important points in connection 

 with Prof. Barnard s observations of Jupiter's satellites, recently 

 published in that journal and in the Monthly Noticei. In the 

 first place, the results announced by Prof. \V. II. Pickering in 

 1893 (see Natltre, vol. xlvii. p. 519), with regard to the forms 

 jand rotations of these bodies, are not conlirmed by Prof. 

 jBarnard's observations. Next, Prof. Barnard has found that 

 jail the Jovian satellites are spherical, whereas Profs. Schaeberle 

 ^aiid Campbell announced in 1S91 that Satellite I. was ellipsoidal, 

 with its longest axis directed towards the centre of Jupiter. It 

 Iwas also concluded by these observers that the periods of rota- 

 [tion and revoluiion of the first satellite were equal ; but Prof. 

 Barnard says that his oliservations lead to a dilTerent result. 

 I-Vnother point upon which Prof. Barnard's recent observations 

 Ihave thrown light, is the appearance of the first satellite when 

 jprojected upon Jupiter. It will be remembered that the satellite 

 |was seen in transit as a double body in 1S90, but Prof. Barnard 

 jhas shown that the apparent duplicity was due to simple con- 

 (trasts between bright regions on the planet and two extensive 

 dusky polar caps on the satellite (see.VATUitE, vol. xlix. p. 300). 

 Other strange appearances of satellites during transit can \it 

 explained in a similar manner. Prof. W. II. Pickering has 

 criticised the statement that the assumed belt on the first 

 satellite is a permanent one (Asly. A'iii/'/. 3229), and says that 

 It certainly did not exist at the time of the opposition of 1892, 

 during the period covered by the Arequipa observations. He 

 points out that, upon his meteoric hypothesis, it is not unlikely 

 that belts should form and then disappear. It is a fairly common 

 belief among astronomers that the satellites of Jupiter can be seen 



NO. I2S2, VOL. 50] 



through the planet's limb during occultation. On this point. 

 Prof. Barnard says : " In my mind this [the observation of the 

 transparency of Jupiter's limb] has been due to poor seeing, a 

 poor telescope, or an excited observer. For nearly fifteen 

 years I have observed Jupiter and his satellites, and with tele- 

 scopes all the way from five inches up to thirty-six inches have 

 tried to see this phenomenon. I have often watched the satel- 

 lites under first-class seeing with the 1 2-inch here [Mount 

 Hamilton] at occultation, but have never seen one of them 

 through the limb of Jupiter, though that phenomenon was 

 specially looked for." It will 'oe seen from these points that 

 Jupiter and his satellites still offer a wide field for invesiigalion. 



The Mass of the Asteroids.— Mr. B. M. Rosrel contri- 

 butes to the Johns Hopkins Univcrdly Circular for April a 

 preliminary note on the probable mass of the asteroids. He 

 has investigated the secular perturbations to which a ring of 

 matter, such as the asteroids form round the sun, would give 

 rise. The problem divides itself naturally into two parts — 



(1) to determine the combined mass of the asteroid belt ; and 



(2) knowing the mass, to derive the secular perturbations of th<.- 

 elements of the orbits of certain of the major planets caused by 

 this elliptic ring of matter. If the total number of the asteroids 

 were known, it would only be necessary to determine the most 

 probable mass of one member of the group to derive the com- 

 bined mass of the whole group. But this is not the case, so 

 Mr. Roszel has contented himself with determining the mass 

 from a study of two hundred and sixteen of the minor planets 

 at present known. The magnitudes of these bodies vary from 

 magnitudes 6 to 15 5, the greater number lying between mag- 

 nitudes II and 12. From photometric observations. Prof. 

 Pickering derived for Vesta a diameter of 319 ± 10 miles. 

 (Prof. Barnard's recent observations only assign the planet a 

 diameter of 237 ± 15 miles). Now the ratio of the total quan- 

 tities of light reflected by two planets at the same distance from 

 the observer is equal to the ratio of the squares of their 

 diameters. Utilising this fact, Mr. Roszel has been able to 

 determine the volumes of the two hundred and sixteen asteroids 

 referred to in terms of the volume of Vesta. Assuming 

 Pickering's dimensions of Ves'.a to be correct, it appears that 

 it would take roughly three hundred and ten asteroids of the 

 sixth magnitude, or twelve hundred of the seventh, to equal our 

 moon in volume. And in round numbers the combined volume 

 of a ring of two hundred and sixteen would be only one two- 

 hundredth part of that of our satellite. Assuming a mean 

 density equal to that of Mar^, the ma<s of the zone of asteroids 

 comes out as about one one-hundred and seventieth part of the 

 mass of the moon. From these considerations Mr. Roszel 

 thinks that the probable mass of the entire asteroid belt is some- 

 where between one-fiftieth and one one-hundredth part of that 

 of our moon. 



Ephemeris ok Gale's Comet. — The following ephemeris 

 (for Berlin midnight) is abstracted from one given by Prof. 

 Kieutz in Astronomische Nachricliten, Nos. 3227 and 3229 : — 



R.A. Dccl. Dfight- 



\\. m. s. o , ncss. 



May 26 ... 10 44 37 ... N. 36 11 -3 ... o'So 



30 ... 10 57 40 ... 38 109 ... 060 



June 3 ... II 9 14 ... 39 393 ... 040 



7 ... II 19 jS ••• 40 45 6 ... 03? 



II ..- II 29 12 ... 41 356 ... 0-26 



15 ... II 38 7 ... 42 13 I ... 0-2I 



19 ... II 46 31 ... 42 410 ... 017 



23 ... II 54 53 ... 43 1-4 .. o 14 



The brightness on April 3 has been taken as unity. 



The comet was photographed by the Brothers Henry, at 

 Paris Observatory, on May 5. The photograph was obtained 

 with an exposure of forty minutes, and showed a lail, about 

 four degrees in length, divided, at a short distance from the 

 head, into two branches separated by an angle of about three 

 degrees. The mean direction of the two parts of the tail was 

 very nearly perpendicular to the direction of the comet's 

 motion. 



SOME LONDON POLYTECHNIC INSTITUTES. 



TT is only in recent years that any attempt has been made 



to supply the demand for technical education in London. 



Not so very long ago the question as to whether such 



education was desirable for the working classes was gravely 



