‘ 
t 
| Fuly 24, 1873) 
wees” 7 
I did not introduce any iron or magnesia, as I regard them as 
accidental impurities varying in amount. 
When a mixture of the above composition is exposed to the 
flame of the oxyhydrogen blowpipe, it fuses with almost exactly 
the same phenomena as with the natural beryl. It is, however, 
as might be anticipated from the absence of iron and chromium, 
much easier to get a colourless transparent bead with the mix- 
ture than with either emeralds or beryls. The greatest difficulty 
in this respect is, of course found with emeralds. The specific 
gravity of the artificial fused globules was 2°42, or almost 
exactly the same as the density of native emeralds and beryls 
after fusion. 
When a small portion of chromic oxide is added to the 
artificial mixture and the whole is subjected to fusion, the re- 
sulting bead is of a rich yellowish green, and in many experi- 
ments approached to the emerald tint; but, asa rule, the 
colour is more of a faded leaf-green; and, although I have 
never obtained a globile of the vivid tint of a fine emerald, the 
glasses, when well cut, are quite beautiful enough to serve as 
jewels. Prolonged heating gradually diminishes the colour, 
the bead gradually becoming of the palest bottle-green, and, 
finally, nearly colourless. This result is the same as with the 
emerald. | 
The metallic oxide which yields the finest tints when fused 
with opaque beryls, or the artificial mixture, is that of cobalt. 
The manner in which this oxide withstands the intense heat of 
the oxhydrogen flame is remarkable. All tints, from nearly 
black to that of the palest sapphire, can be obtained, and the 
resulting glasses, when cut, are extremely beautiful, and have 
almost the lustre of crystallised gems. 
The globules obtained by fusing the artificial mixture of 
beryl ingredients with didymium oxide show the characteristic 
absorption-spectrum of that metal in a very perfect manner, the 
lines being intensely black. Even when the bead is quite 
opalescent from insufficient heating, the black lines are beauti- 
fully distinct in the spectroscope. With a large quantity of 
didymium oxide the beads are of a lively pink, becoming more 
intense by artificial light, and, when cut, form very pretty gems. 
The presence of didymium in sufficient quantity raises the specific 
gravity to 2°59,being nearly the same as that of the emerald 
before fusion. 
Conclusions.—The evidence given in this paper, showing that 
colourless beryls may contain as much carbon as the richest 
tinted emerald, taken in conjunction with the ignition experi- 
ments, and the results of the fusion cf chromic oxide with colour- 
less beryls, and with an artificial mixture of the same composi- 
tion, leave me no room to doubt the correctness of Vauquelin’s 
conclusion, that the green colour of the emerald is due to the 
presence of chromic oxide. 
The fact that emeralds and beryls lose density when fused 
cannot properly be cited as proving that they have been made in 
nature at a low temperature ; for it is quite possible that they were 
crystallised out of a solution in a fused mass, originally formed 
at a temperature high enough to keep the constituents of the 
emerald in a state of fusion, and that the crystals developed 
themselves during a slow process of cooling or evaporation. The 
method employed by Ebelmen for the artificial production of 
chrysobery], namely, heating alumina, glucina, and carbonate of 
lime with boracic acid in a porcelain furnace until a portion of 
the menstruum had evaporated, yielded crystals of the true 
specific gravity, showing the density of minerals to be less de- 
pendent on the temperature at which they are produced than 
upon their crystalline or amorphous state. 
One crystalline gem (the ruby) has undoubtedly been pro- 
duced in nature at a high temperature. I-have frequently 
repeated Gaudin’s experiment on the artificial formation of this 
stone, and can confirm most of his results. I did not, however, 
find the density to be quite the same as the native ruby or 
sapphire, which is, in different specimens, from 3°53 to 3°56. 
Artificial rubies of the finest colour made by me by Gaudin’s 
process had a specific gravity of 3°45, which is not 3 per cent. 
lower than that of the ruby. The reason for this close approxi- 
mation will be found in the fact that fused alumina crystallises 
on cooling, The crystallisation is, however, confused and im- 
perfect, which causes the resulting product to be only partially 
transparent, and to have a slightly lower specific gravity than 
the natural gem. It is consequénfly scarcely correct to call the 
fused stones made by Gaudin’s process “‘ artificial rubies.” 
I have convinced myself that rubies have been formed in 
nature at a temperature equal, or nearly equal, to that of the 
a 
NATURE 
255 
fusing-point of alumina, from the circumstance that the reaction 
between chromic oxide and alumina, which results in the deve- 
lopment of the red colour of the gem, is not effected at low or 
even moderately high temperatures, but requires a heat as high 
as that of the oxyhydrogen blow-pipe. It is not necessary that 
the chromium should be presented to the alumina in the form 
of chromic acid. It appears, therefore, that the red colour of 
the ruby is not caused by the presence of chromic acid. It is, 
in fact, a colour reaction sui generis between alumina and chromic 
oxide, which, as far as my experiments have gone, only takes 
place at very elevated temperatures, 
SOCIETIES AND ACADEMIES 
LONDON 
Royal Horticultural Society, June 18.—Scientific Com- 
mittee.—Dr. Hooker, C.B., F.R.S., in the chair.—Dr. Capa- 
nema, from Rio Janeiro, described the destruction in Brazil of 
orange, peach, and cotton plants, more especially at Milagres, 
in the provincé of Ciara, from the attacks of a Coccus. An 
orange tree of historic interest more than 200 years old had 
been destroyed by this insect.—Dr. Masters, F.R.S., reported 
upon a double-flowéred variety of Lobelia erinus. The calyx 
was normal, the corolla was affected by a dédoublement, the 
stamens were more or less petaloid, the ovary was represented 
by obscure carpellary leaves bearing ovules on the margins.— 
Mr. Lane, of Berkhampstead, sent a cutting of a yellow-leaved 
variety of Laburnum which had broken from an old stem of the 
ordinary kind previously budded some time before with the 
yellow one. The bids which were inserted died, but as in other 
cases the tendency to variegation in the foliage had been com- 
municated to the stock.—The Rev. M. J. Berkeley stated that 
he had provisionally referred the thread blight which had attacked 
the tea plantations in India to Corticium repens Berk. 
July 2.—A. Smee, F.R.S., in the chair.—Prof. C. Babington 
sent flowers of a potato in which the petals were replaced by 
stamens.—Dr. Denny sent a Pelargonium which showed an in- 
teresting reversion to one of the original wild forms (P. znguinans). 
It had been raised from Wellington as the seed parent, and 
Marathon as the pollen parent, both varieties of the nose-gay 
class. 
EDINBURGH 
Scottish Meteorological Society, July 2.—Sir Thomas 
Buchan Hepburn in the chair.—The Council reported to the 
General Meeting, that there are 92 Stations in Scotland in con- 
nection with the Society, 5 in England, 4 on the Continent, 2 in 
Iceland, 1 in Fard, and 1 in South America; that there are 9 
honorary, 16 corresponding, and 557 ordinary members ; that 
the value of the Instruments at the Society’s Stations amounts to 
1,173/., of which 218/. belongs to the Society, and the rest to 
local parties ; and that during the past ten years, 63 certified 
Barometers, 59 louvre-boarded boxes, on Stevenson’s pattern, 
for holding thermometers, had been despatched to the Society’s 
Stations, and about 800 thermometers compared in the office. 
In reply to an application from a Committee of the British 
Association, the Council have intimated that they will, as 
hitherto, be glad to make the unpublished meteorological obser- 
vations in their possession available to scientific men, and free of 
charge, in so far as the limited means of copying at their dis- 
posal will enable them to do so,—Mr, Buchan gave in the report 
from the Committee which had been appointed to inquire into 
the subject of the Herring Fisheries in relation to Meteorology. 
The returns of the fishings at Wick, Buckie, Peterhead, and 
Eyemouth, for six seasons of thirteen weeks each (1867-1872) 
had been examined, and the catches of herring compared with 
the mean daily temperature of the sea and that of the air with 
the height of the barometer, the direction and force of the wind, 
storms of wind, thunderstorms, Auroras, and rain. The fishing 
season at these places, in common with the whole cf the east 
coast of Great Britain, from Scotland to Flamborough Head, 
occurred during July, August, and September, ending some- 
what earlier at the northern than at the southern stations. 
From the mean daily catch at Wick and Buckie, from 
which daily returns had been made, it is seen that during 
the six years the largest average catches were taken be- 
tween the 13th and 22nd August, and the whole herring season 
began about the 19th July, and ended on the 2nd September. 
That period agreed exactly with the highest mean daily 
temperatures of the sea during the year, and the period of the 
