DECEMBER 3, 1903] 
NATURE 
113 
Tue determination of vapour densities at high tempera- 
tures by application of the diffusion method of Bunsen is 
discussed in a paper by Prof. Emich communicated to the 
Vienna Academy. For one and the same gas at different 
temperatures the time of diffusion of a given volume should 
be proportional to the square root of the absolute tempera- 
ture. Experiments with tubes of porcelain, platinum, and 
jridium show that this requirement is approximately 
fulfilled, and investigations on diffusion are now being 
carried out up to a temperature of 2000° C. 
Accorpinc to Mr. W. Ackroyd, colour changes are 
frequently brought about by the action of radium rays. 
These changes have been examined by embedding a radium 
bromide tube in the substance experimented upon. After a 
few hours sodium chloride becomes orange or buff coloured, 
potassium chloride becomes violet but returns to its original 
colour very quickly after removal of the exciting cause. 
Sodium bicarbonate and potassium metabisulphite are 
changed to amethyst colour after twenty-four hours’ ex- 
pcsure. 
WE have received the second number of vol. i. of the 
Journal de Chimie physique, published under the direction 
of Prof. Guye, of Geneva. The number contains two 
interesting papers, one by Prof. Duhem on the eutectic and 
transition points of binary mixtures which give rise to 
mixed crystals, the other by Prof. Guye on the electrolysis 
of alkaline chlorides. The reviews of current physico- 
chemical literature which form the second part of the 
publication are exceedingly well written, and the papers 
reviewed are, moreover, of quite recent publication, a state- 
ment which cannot be made of many abstracts in other 
physicochemical journals. 
In the November issue of the Moniteur Scientifique M. 
Combes discusses the various attempts which have been 
made to obtain the diamond artificially. Against the 
common supposition that the diamond can only be produced 
at high temperatures, the author cites several observations 
which seem to indicate that natural diamonds, at any rate, 
-cainot have been formed under such conditions. The hypo- 
thesis that high pressures are necessary for the artificial 
production of diamonds is not in accord with actual experi- 
mental facts, and the author arrives at the conclusion that 
in the experiments of Moissan the pressure plays no essential 
part, and that the optical properties and the analysis of 
the crystals obtained by this chemist do not warrant the 
conclusion that these are to be regarded as diamonds. 
Tue additions to the Zoological Society’s Gardens during 
the past week include a Bonelli’s Eagle (Nisaétus fasciatus), 
European, presented by Mr. G. H. Baxter; a Matamata 
Terrapin (Chelys fimbriata) from Guiana, presented by Mr. 
E. Bieber; a Yellow-fronted Amazon (Chrysotis ochro- 
cephala) from Guiana, a Lesser Sulphur-crested Cockatoo 
(Cacatua sulphurea) from Moluccas, a Common Buzzard 
(Buteo vulgaris), European, deposited; an Ourang-outang 
(Simia satyrus) from Borneo, purchased. 
OUR ASTRONOMICAL COLUMN. 
ASTRONOMICAL OCCURRENCES IN DECEMBER :— 
Dec. 3. 6h. 44m. Minimum of Algol (8 Persei). 
6. 17h. 40m. to 18h. 41m. Moon occults A Geminorum 
(Mag. 3 6). 
It. Predicted perihelion passage of Brooks’s periodical 
comet (1889 V-1896 VI). 
11-13. Epoch of Geminid Meteors (Radiant 108° + 33°). 
14. 12h. Meas in conjunction with the Moon. 
Ons, S: 
NO. 1779, VOL. 69] 
Venus | 
Dec. 15. Venus. Illuminated p. rtion of disc =0'586. 
16. 3h. 7m. to 6h. 26m. Transit of Jupiter’s Sat. Ill. 
20. 12h. Mars and Saturn in conjunction (Mars 
09933! 1S.): 
22, 12h. Sunenters Capricornus. Winter commences 
23. 7h. 17m. to 10h. 36m Transit of Jupiter’s Sat. III. 
,, 8h. 27m. Minimum of Algol (8 Persei). 
25. 6h.om. Jupiter in conjunction with the moon 
(Jupiter 2° qo’ S.). 
26. 5h. 16m. Minimum of Algol (8 Persei). 
,» 23h.om. Neptune in opposition to the sun. 
31. 12h. som. Near approach of moon to Aldebaran 
(a Tauri). 
», 18h. om. Mercury at greatest elongation (19° 30’ E. ) 
DETERMINATION OF STANDARD STELLAR VELociTIES.—In 
accordance with the cooperative scheme for regularly deter- 
mining the velocities of certain standard stars, Profs. Frost 
and Adams have, during the past twelve months, made in- 
dependent observations of the radial velocities of thirteen 
stars, the results of which are given herewith :— 
Mean 
Star velocity in 
kilometres per sec. 
a Arietis —13°7 
a Persei - 2'1 
B Leporis —12°4 
8 Geminorum + 3°4 
a Crateris +474 
a Bootis ... - 48 
8 Ophiuchi -I11'l 
vy Aquilz — 18 
y Cephei —41°2 
e Pegasi... + 6°2 
y Piscium —10°9 
« Aurigze +19'0 
e Leonis 55 
The Bruce spectrograph of the Yerkes Observatory, with 
various cameras attached, has been used, and, in the 
majority of cases, the spark spectrum of titanium has been 
employed to give the standard comparison wave-lengths. 
Three photographs of each star have been obtained, except 
in the case of B Leporis, where the low altitude and poor 
observing conditions have prevented more than one being 
taken. A range of 1-8 km. in the determined velocities of 
« Leonis indicates the existence of a real variation, but 
more photographs must be measured before the point can 
be decided. An unaccountable difference of —o-5 km. is 
shown between the velocity of Arcturus as determined from 
eight earlier plates and that obtained from the five plates 
recently obtained, unaccountable because in the spectrum 
of this star the lines are so well defined (Astrophysical 
Journal, vol. xviii., No. 4). 
New ELEMENTS FOR 7 AQUILE.—From 352 observations 
of the magnitude of » Aquila, made at the Lyons Observ- 
atory between June 3, 1898, and December 22, 1902, 
M. M. Luizet obtained the times of fifty-five maxima and 
fifty-three minima, and, on comparing them with those 
calculated from the elements obtained by Schiir, and pub- 
lished in ‘‘ Chandler’s Third Catalogue,’’ he found that a 
difference amounting, in the mean, to +02 day existed, 
and therefore thought it advisable to compute a new set of 
elements. This he did by employing the maxima and 
minima data used by Schiir, and combining with them the 
results obtained from his own observations; the result 
showed that it was necessary to apply a correction of 
0-106-+0-021 day to the original epoch of maxima, and 
0-0166 +0:035 day to that of minima, and, in each case, a 
slight correction to the length of the period. 
Applying these corrections to the data used by Schiir, one 
obtains for the original epochs 
Maxima 2396168-738 days, 
Minima 2396166.365 days, 
| and for the length of the period 
7-176382 days. 
