Dee. 15, 1870] 
NATURE 
139 

Lresus ctenizoides, from Syra, where it lived under stones and fed 
on large grasshoppers ; it had remained without food since July. 
The paper read was ‘‘A Monograph on the Zphemeride,” by 
the Rev. A. E. Eaton. Mr. G. H. Verrall was elected a member 
of the Society. 
London Institution, December 1.—Prof. Morris delivered 
a lecture ‘*On Gems and Precious Stones,” in which the 
characters of the various mineral substances used in jewellery 
were minutely explained. The diamond, the only representative 
among the gems of the elementary bodies, received special atten- 
tion. The lecturer referred to its crystalline form, cleavage, 
hardness, specific gravity, and refractive power, the characters by 
which it is distinguished from crystallised quartz and other 
minerals. He described the dull and unattractive varieties of 
the diamond known as ‘‘carbonado” and “boort,” and pointed 
out their application to steel-engraving, glass-cutting, and rock- 
boring. The mineralogical and geological features of the 
diamond-beds of India, Brazil, Borneo, South Australia, and 
South Africa, were discussed at length, and the frequent associa- 
tion of diamonds with itacolumite, gold, and rutile was referred 
to as a subject worthy of careful investigation. Other precious 
stones, such as the sapphire, ruby, emerald, beryl, topaz, jargon, 
garnet, spinel, and turquoise, were successively treated of, refe- 
rence being made to their chemical composition, their physical 
properties, and their application to decorative and industrial 
purposes. To illustrate the lecture, Messrs. Blogg and Martin 
contributed a unique series of uncut diamonds exhibiting perfect 
crystalline forms, diamonds from South Africa, and one remark- 
able specimen embedded in the ‘‘ cascalho,” taken from a bed in 
Brazil. Prof. Tennant also contributed a splendid collection of 
diamonds in the natural state. Through the kindness of Messrs. 
Hunt and Roskell, the lecturer was enabled to show a fine series 
of precious stones and models of the great South African 
diamond before and after cutting. To Mr. James Gregory again, 
the lecturer was indebted for a collection of minerals used for 
ornamental purposes, models of celebrated diamonds, and 
samples of the gravels and rocks associated with the diamonds in 
South Africa. 
December 5.—Dr. Odling gave his sixth lecture ‘‘ On Chemical 
Action,” and illustrated his remarks on the circumstances which 
modify chemical action by a series of brilliant experiments, in 
which the oxy-hydrogen blowpipe was largely used. 
Chemical Society, December 1.—Prof. Williamson, F.R.S., 
President, in the chair. The following gentlemen were elected 
Fellows :—H. E. Armstrong, Ph. D., R. Barklie, W. L. Car- 
penter, T, M. Crafts, Prof. of Chemistry in Cornell University, 
J. Dewas, T. Farries, R. Mallet, F.R.S., and Dr. Ogg. Mr. 
Perkin, F.R.S., read a paper “ On some derivatives of Anthra- 
cene.” This was a detailed account of some Anthracene deri- 
vatives, more particularly of the products resulting from the 
action of sulphuric acid upon dibrom and dichloranthracene. 
Dichloranthracene is most conveniently prepared by passing 
chlorine gas over benzole, holding about one-fifth its weight of 
purified commercial anthracene in suspension, until the mixture 
becomes a crystalline mass. © The product is then brought on to a 
linen filter, drained, washed with cold benzole, dried, and then 
further purified by distillation and subsequent recrystallisation 
from benzole. Thus obtained it appears in golden yellow 
needles, The mean of several analyses gave 67°91 per cent. C, 
3°34 per cent. H, and 28°70 per cent. Cl, which numbers agree 
perfectly with the formula of Graebe and Liebermann, C,, H, Cl.. 
Dichloranthracene, when greatly heated, sublimes in beautiiul 
needles, which may be obtained of considerable size. It is 
fluorescent in the solid state as well as when in solution. When 
a boiling solution of dichloranthracene in benzole is added to a 
similar solution of picric acid, the mixture assumes a dark orange- 
red colour, and on cooling becomes filled with small bright 
red needles. These consist of a compound of dichloranthracene 
and picric acid. A determination of the dichloranthracene in 
this body gave numbers closely approximating to those required 
by the formula, C,,H, Cl, C,; H, (N O,),O. Dibromanthra- 
cene. This product was prepared by Graebe’s process. It 
was, however, purified first by distillation and then by crystal- 
lisation from benzole. Thus obtained, it is of a golden yellow 
colour. It gave, on analysis, numbers closely agreeing with 
those required by the formula 
C,,,.H, Brs 
Like dichloranthracene, this body produces a beautiful red com- 
pourd with picric acid. Action of Sulphwic Acid on Dichlo- 

ranthracene. Dichloranthracene, when submitted to the action 
of fuming sulphuric acid, dissolves, forming a bright green solu- 
tion, and is at the same time converted into a sulpho-acid. To 
prepare this acid, one part of dichloranthracene is added to about 
five parts of fuming sulphuric acid, and the mixture heated for a 
short time in the water bath. It is then gradually poured into 
several times its bulk of water and treated with carbonate of 
barium until all the sulphuric acid is neutralised. The acid 
solution, when filtered off from the sulphate of barium, is eva- 
porated to a small bulk. When sufficiently concentrated, it 
becomes, on cooling, a shiny mass of minute orange-yellow 
coloured crystals, which may be drained on a porous tile.” ‘This 
acid has not been analysed, but, from the composition of its salts, 
evidently possesses the formula 
: { HSO, 
Cis He Cl) HSO, 
Mr. Perkin therefore proposes to call it disulphodichloranthracenic 
acid. It is easily soluble in water from which it is precipitated 
upon the addition of a little concentrated sulphuric or hydro- 
chloric acid. It possesses a strongly acid taste and character, 
The acid forms salt with sodium, barium, calcium, and strontium. 
The barium salt is remarkable for its insolubility in hydrochloric 
acid. 
Dibromanthracene yields with strong sulphuric acid an analog- 
ous disulphodibromanthracenic acid, 
: . | HSO 
Gis He Be } so, 
Its sodium, barium, &c., are similar to the salts of disulpho- 
dichloranthracenic acid. 
Oxidation of disulphodichloro, and disulphodibromanthracenic 
acid. These sulpho-acids, when subjected to the influence of 
oxidising agents, rapidly decompose, exchanging their chlorine 
or bromine for oxygen, and are thus converted into disulphan- 
thraquinonic acid. 
HSO, , | HSO, 

Gate), {Hs0' +0: = Ci Hy (0,)" { Hso? + C1Cl 
==) AR ee 
Disulphodichloranthracenic acid. D.sulphanthraquinonic acid. 
HSO, a n§ HSO ; 
C,, Hy Bry TSO! + Os = Cia Hy (0,)" | Heo! + Br Br 

Disulphodichlorantixracenic acid. Disulphanthraquinonic acid. 
An analogous result is also obtained by treating them with con- 
centrated sulphuric acid, the following reactions taking place :— 
S¢ SO, 
Gye jHSO, jHSO, 
2{HSO, t H2S04=CisHo(Oo)" | go3 +2 HC1+S0, 
HSO3 
Gukie Brat HO? + 2H, S04 = Cy He (0,)'{ 182+ Br. + 280, +2H,0 
Anthracene when pure in large crystals shows a beautiful fluo- 
rescence, and so do many of the anthracene products, though 
curiously their solutions are comparatively poor in this respect. 
Anthracene and dichloranthracene in the state of vapour are not 
at all fluorescent, and moreover, a ray of light sent through the 
length of about four inches of the vapour of either body, still 
retains its power of rendering fluorescent bodies luminous. The 
experiments in this direction are, however, not yet concluded. 
On sealing up anthracene in a long vacuum tube with platinum 
poles, and allowing the discharge from an induction coil to pass 
through the tube, nothing particular is observed except the 
beautiful fluorescence of the crystals of anthracene. On exami- 
nation with the spectroscope, the light showed carbon and nitro- 
gen lines, the latter arising from the presence of a little air in the 
tube. Upon heating the tube, however, somewhat strongly, so 
as to volatilise the hydrocarbon, the ordinary colour of the dis- 
charge changed to a magnificent deep azure blue, and. what is 
remarkable is that this blue light, when examined with the spec- 
troscope, is perfectly continuous, and consists of blue with a 
little green. Dichloranthracene, when heated ina similar manner, 
gives an analogous result, but suffers a good deal of decomposi- 
tion, anthracene changing but little. These curious results do 
not appear to be due to the fluorescent character of the substances 
employed, as napthaline produces a similar effect, the blue light, 
though not so intense, being continuous. It must be observed, 
however, that this hydrocarbon undergoes considerable change, 
becoming brown and oily. Anthracene heated in a vacuum tube 
in the same way gives a greenish blue light, showing faint carbon 
bands. On exposing a solution of disulphodichloranthracenic 
acid to the light of one of the recent displays of the aurora borealis 
it was very strongly illuminated, as might be expected. Moonlight, 
