]rarch lo, 1887] 



NA TURE 



447 



a-it-lanils from Ailulis (Anncsley) B.iy southwards to Assab, 

 ill stations at Hawakil, Mader/and Ed ; (3) territory placed 

 ler the absolute sovereignty of Italy — Assab and surroiiiidin; 

 ■'.riot stretching for thirty-six miles between Ras Darmah and 

 1^ Sinthiar, and including the neighbouring islets, annexed in 



:!y 1882. Massowa, the centre of government, occupies a strong 



i^tion on an island connected by an embankment with Taulud, 



1 I defended by forts at Gherar and on the Abd-elKader 

 ninsula. Since the Italian occupation it has been largely 



jbuilt in Kuropean style, and according to a rough census 

 laken in September 1S85 has a population of about 5000. 

 There are several mosques, a Catholic church attached to the 

 I'rench mission, and a meteorological observator)' where obser- 

 • ions have been regularly recorded since May 18S5. During 



ii< period the te-nperature has varied from I9°'i C. in January, 



' 42° '8 in .\ugust, with a mean of about 26° '4. 



Dr. Otto Kri'mmet. publishes in the Zeilschrift fiir wisscn- 

 'mftlUlie Geographic, under the title of " The Relief of the 

 \ustralian Mediterranean," i.e. the sea lying between Australia 

 1 the islands on the north, some valuable data as to recent 

 mdings therein. They are as follows : — 



S I^t. E. Long. Depth in fathoms 



4° 45' >23''40' 90 



4° 29' i23°48' no 



4° 14' '23' 58' 80 



3° 58' 124° 10' 55 



3° 4S' 124° 18' bo 



3° 32' «24"34' 60 



3° 22' 124° 5«' 75 



3° 12' 125° 10' 90 



3' 3' 125° 22' 120 



2° 53' 125° 36' 105 



2' 45' 125° 48' 90 



( )n the other hand. Dr. Kriimmel recalls the fact that we have 

 the neighbouring Banda Sea in a depth of 2000 to 3000 fathoms. 

 These data seem to indicate that between Celebes and Buru there 

 exists a sub- oceanic ridge. We cannot say whether it extends 

 over Ceram to N'ew Guinea, and so indicites an ancient land- 

 bridge between Asia and Australia, for between Ceram and New 

 ' '. iiinea we have no soundings, and those on the borders of the 

 v.tit between Kuru and Ceram are from 1500 to 3000 fathoms. 

 Mr. W. Griggs has published a facsimile of the fauious map 

 of the world lent by the Pope to the Colonial and Indian Ex- 

 hibition, and placed in the West Indian section. This map, 

 which is a copy of the chirt in which Pope Alexander drew the 

 line dividing the possessions of Spain and Portugal in the New 

 World, w.is beiuealhed to the Pope by the last of the Borgias 

 in 1830, and has since then been preserved with much jealousy. 

 It is drawn on a sheet of vellum seven feet long by three broad. 

 The colours of the original are reproduced. 



ON RADIANT-MATTER SPECTROSCOPY:— 



EXAMINATION OF THE RESIDUAL GLOIV^ 



II. 



I N the search for bodies giving discontinuous phosphorescent 

 ^ spectra I have submitted a great number of earths and com- 

 binations to the electric discharge in vacuo, and have noted the 

 results. .\s the superficial phosphorescence apart from the 

 composition of the emitted light has formed the subject of 

 several recent papers by my friend M. Lecoq de Bofsbaudran, 

 before the .-Xcademie des Sciences, it may be useful if I place 

 on record some of the more striking facts which have thus come 

 under my notice. The bodies .are arranged alphabetically, and, 

 unless otherwise explained, were tested in the radi.ant-ma'ter 

 lube in the form of ignited sulphates. 



Alumina, in any of the forms which give the crimson line 

 (\6942— 6937), has a very persistent residual glow. In the 

 phosphoroscope rubies shine with great brilliancy. This phos- 

 phorescence of alumina has recently been the subject of a paper 

 read before the Royal .Society (Roy. Soc. Proc. vol. xlii., 1S87, 

 p. 25). 



Aiiltmoiiy oxide with 95 per cent, of lime (in the form of 

 ignited sulphate). — White phosphorescence, the spectrum show- 

 ing a broad space in the yellow, cutting the red and orange off. 



' Paper rsad before the Royal Societj- by Mr. William Crooltes, F.R.S.. 

 on February 17. Continued from p. 428. 



In the phosphoroscopes the residual glow is very strong, nni of 

 a greenish colour. The spectrum of the residual light shows 

 that the red and orange are entirely obliterated, leaving the 

 green ,and blue very luminous. Antimony oxide with 99 per 

 cent, of lime gives a pale yellowish phosphorescence, which on 

 heating turns red. In other respects it is like the 5 per cent, 

 mixture. 



Arscnious acid with 99 i>er cent, of lime gives a greenish. 

 white phosphorescence like ])ure calcium sulphate. 



Barium S per cent., calcium 95 per cent. — The sulphates 

 phosphoresce green, with specks of yellow and violet. The 

 spectrum is continuous, with slight concentration in the red, 

 great concentration in the green, and in the orange a broad 

 black band hazy at the edges. 



Bismuth 15 percent., calcium 85 per cent., phosphoresces of 

 a bright reddish orange. The spectrum shows a tolerably sharp 

 and broad dark band in the red and orange, and a sirong con- 

 centration of light in the green and blue ; the spectrum being 

 continuous and divided into two parts by a black band in the 

 yellow, as in the case of the antimony-calcium spectrum. In 

 the |>hosphoroscope the red and orange disappear and the green 

 and blue remain. Bismuth 7 per cent., calcium 93 per cent. — 

 The action is similar to the 15 per cent, mixture, except the 

 colour of the phosphorescence, which is whiter. In the phos- 

 phoroscope the red and orange below the dark band is cut ofT. 

 With 2 per cent, of bismuth the same phenomena occur. With 

 0'5 bismuth the phosphorescence is greenish blue and the spec- 

 trum is continuous, with strong concentrations in the orange 

 and green. The phosphoro cope cuts oiif the red and orange. 



Cadmium I percent., calcium 99 per cent. — Similar to calcium 

 sulphate, q.v. 



Calcium sulphate was prepared from a colourless and trans- 

 parent rhomb of Iceland spar which had been used for optical 

 ])urpo3es. It was dissolved in nitric acid, the nitrate was 

 decomposed with distilled sulphuric acid, and the ignited 

 sulphate tested in the tube. The phosphorescence is bright 

 greenish blue without bands or lines. In the phosphoroscope 

 the colour is a rich green ; the spectrum shows the red and 

 orange entirely cut off, leaving the green and blue ; the blue is 

 especially strong. 



Calcium sulphates jirepared from Prof. Breithaupt's calcites 

 (Phil. Trans., 1885, Part II., p. 697) were re-examined. .-Ml 

 phosphoresce with the normal greenish-blue glow of calcium, 

 except No. n, which gives a reddish glow. A minute trace of 

 samarium was found in this calcite, but not enough to affect the 

 colour of the glow. In the phosphoroscope all the specimens 

 give a continuous spectrum beyond the yellow, the red and 

 orange being cut off as uual. 



Chromium 5 per cent., calcium 95 per cent., as sulphates, 

 gives a pale reddish phosphorescence. In the phosphoroscope 

 the colour is green, and the red and orange are cut off. I per 

 cent, of chromium with calcium phosphoresces green in the cold, 

 and becomes a red when slightly heated. The behaviour of 

 chromium with aluminium has already been described (Roy. Soc. 

 Proc. vol. xlii. p. 28, ct rq.) 



Co//cv sulphate wi:h 95 per cent, calcium sulphate behaves 

 like calcium sulphate. 



Diaiinnds phosphoresce of various colours. Those glowing 

 pale blue have the longest residual glow, next come those 

 phosphorescing yellow ; I am unable to detect any residual gljw 

 in diamonds phosphorescing of a reddish colour. A large 

 diamond of a greenish hue, very i)hosphorescent, shines almost 

 as brightly in the pho:phorosc^pe as out of it. 



Gluciiia phosphoresces of a rich blue colour. There appears 

 to be no residual glow with this earth in the phosphoroscope. 



Lanthanum. — .■Ml the specimens of lanthanum sulphate I 

 have examined in the nadiant-matter tube phosphoresce of a 

 reddish colour, and give a broad hazy band in the orange, with 

 a sharp line— l/A'280— superposed on it. This is identical with 

 the line of Gt, one of the constituents of the samarium phos- 

 phorescent spectrum. Calcium added to lanthanum changes the 

 colour of the phosphorescence from red to yellowish, and brings 

 out yttrium and samarium lines, these metals being present as 

 impurities ; the G5 and Ga lines are also seen, but the space 

 which should be occupied by the G5 green is now a dark space. 

 I have shown that when G5, Ga, and G/3 are present in very 

 small quantities with lime, the lines of GSand (la are intensified, 

 while that of Gj8 is weakened. This new result seems to show 

 that if only a small trace of Gj8 is present with lime and lan- 

 thanum, the green line is not only suppressed, but the quenching 



