8, 1873] 
Hy (Oa 
that itis dioxyanthraquinone C,, H, (HO), 
from what is known to take place with other quinone derivatives 
it should be formed from this dibromoanthraquinone on boiling it 
_ with potash or soda and then acidulating the solution. They 
try the experiment, and describe how, contrary at first to their 
_ expectations, on boiling the dibromanthraquinone with potash no 
change occurred, but afterwards, on using stronger potash and a 
higher temperature, they had the satisfaction of seeing the liquid 
little by little become of a violet colour ; this shows the formation 
of alizarine. Afterwards, on acidifying this solution, the alizarine 
separated out in yellowish flocks. On volatalising it they got 
it in crystals, like those obtained from madder. On oxidising it 
with nitric acid, they get phthalic acid ; and on precipitating it 
with the ordinary mordants or other metallic solutions, they get 
compounds exactly comparable to those from the natural product. 
_ Every trial confirms their success, so by following firmly theo- 
_ retical considerations, they have been led to the discovery of the 
means of artificially forming this important organic colouring 
matter. A special interest must always attach itself to this 
_ discovery, for it is the first instance in which a natural organic 
_ colouring matter has been built up by artificial means ; now the 
F chemist can compete with Nature in its production. Although 
4 
I 
om] 
Sept. 
. 
lyr 
: 
H 
and if so, judging 
‘the first, it is a safe prediction that it will not long be the only 
one ; which colouring matter will follow next it is impossible to 
_ say, but sooner or later that most interesting one, scientifically 
_ and practically, indigo will have to yield to the scientific chemist 
_ the history of its production. Returning for a moment to the 
_ percentage composition of alizarine, now that we know its con- 
stitution, its formula is established, and on comparing it 
(C,, Hg Oy) with all the different formule which have been 
proposed, we see that the one advocated by Schunk was most 
nearly correct, in fact that it differs from it only by two atoms of 
hydrogen. It is not without interest to note that the next most 
important colouring matter in madder. Purpurine, which so 
_ pertinaciously follows alizarine, is in constitution very nearly allied 
_ to it, and is also an anthraecne derivative. 
Scientifically then the artificial production of this natural 
‘ uct was complete, but the practical question, can it be 
made in the laboratory cheaper than itcan be obtained from the 
root, had yet to be dealt with. The raw material, the anthracene, 
a bye-product in the manufacture of coal gas, had as yet only been 
obtained as a chemical curiosity ; it had no market value, its cost 
would depend on the labour of separating it from the tar, and the 
amount obtainable. But with regard to the bromine necessary to 
form the bibromantharquinone it was different ; the use of such 
an expensive re-agent would preclude the process becoming a 
manufacturing one. But could no cheaper re-agent be used in 
place of the bromine, and thus crown this discovery by utilising 
it as a manufactunrig process? It was our countryman, Mr. 
Perkin, who first showed how this could be done, and has since 
proved the very practical and important nature of his discovery by 
ing it out on the manufacturing scale. The nature of 
Perkin’s discovery was the forming in place of a bibromanthra- 
quinone, adisulphoanthraquinone, in a word he used sulphuricacid 
ip place of bromine, obtaining thusa sulpho acid in place of a 
romine substitution compound. The properties of these sulpho 
acids, containing the monovalent groups H SO, which is 
the equivalent to the atom of bromine, is that on being 
boiled with an alkali they are decomposed, and a corre- 
sponding alkaline salt formed; thus the change from the 
anthraquinone to the alizarine was effected by boiling it 
with sulphuric acid. At a high temperature, it dissolves, 
| 
becoming a sulpho acid Cy, Hg HSO, and the further changes 
HS 
follow, as they did with the bromine compound: the sulphuric 
acid boiled with potash is decomposed, and a potash salt of 
alizarin and potassic sulphite are formed ; acid then precipitates 
the alizarin as a bright yellow substance. While Perkin was 
carrying on these researches in this country, Caro, Graebe, 
Liebermann, were carrying on somewhat similar ones in Germany; 
and in both countries have the scientific experiments developed 
into manufacturing industries. My knowledge extends only to 
the English manufactory, and if any excuse be necessary for 
having asked your attention to-day to this long history of a 
single substance, I think I must plead the existence of 
that manufactory as my excuse, for it is not often that purely 
scientific research so rapidly culminates in great practical under- 
takings. Already has the artificial become a most formidable 
NATURE 
419 
opponent to the natural product ; and in this struggle already 
begun there can be no doubt which will come off victorious. 
In the manufactory is rigidly carried out, the exact process I 
have already described to you. In tar there is about 1 per 
cent. of the anthracene; this, in a crude, impure state, is 
obtained from it by the tar-distiller, and sent by him to the 
colour works ; here it is purified by pressure by dissolving from 
it many of its impurities, and lastly by volatalising it. Then 
comes the conversion of it into the anthraquirrone by oxidising 
agents, nitric or chromic acid being used. Then the formation 
of the sulphur compound by heating it with sulphuric acid to a 
temperature of about 260° C. The excess of acid present is 
then neutralised by the addition of lime, and the insoluble calcic 
sulphate is filtered off; to the filtered liquid sodic carbonate is 
added, and thus the calcic salt of the sulpho acid is changed into 
2 
the sodic salt Cj; H,4.NaSO, This is afterwards heated to 
Na SO, 
about 180°C. with caustic soda, thus decomposing the sulphuric 
acid and forming the soda salt of alizarin; and sodic sulphite ; 
the alizarine salt so formed, remains in solution, giving to the liquid 
a beautiful violet colour ; from this solution sulphuric acid preci- 
pitates the alizarine as an orange yellow substance. It is allowed 
to settle in large tanks, and then is run in the form of a yellowish 
sand, which contains either ro or 15 per cent. of dry alizarine ; 
nto barrels, and is in this form sent to the print works, and used 
much in the same way as the original ground madder was used. 
This alizarine mud, as I have called it, containing but 10 per 
cent. of dry alizarine is equal in dyeing power to about eight 
times its weight of the best madder, and is the pure substance 
required for the dyeing in place of a complicated mixture con- 
taining certain constituents which have a positively injurious 
effect on the colours produced. 
The scientific knowledge and energy which Mr. Perkin has 
brought to bear on the manufacture of this colouring matter, 
seems already to have worked wonders, the supply and demand 
jor artificial alizarine are increasing at a most rapid rate, and yet 
the manufacture of it seems hardly to have commenced. The 
value of madder has much decreased, and in fact, judging by 
what occurred in the year of revolution and commercial depres- 
sion, 1848, when the price of madder fell for a time to a point 
at which it was considered it would no longer remunerate the 
growers to produce it, that point has now been again reached, 
but certainly from very different reasons. Last year artificial 
alizarine, equal in value to about one-quarter of the madder im- 
ported into England, was manufactured in this country. This 
year the amount will be much larger. Thus is growing up a 
great industry, which far and wide must exercise most important 
effects ; old and cumbersome processes must give way to better, 
cheaper, newer ones, and lastly thousands of acres of land in 
many different parts of the world will be relieved from the neces- 
sity of growing madder and be ready to receive some new crop. 
In this sense may the theoretical chemist be said even to have 
increased the boundaries of the globe. 
SECTION C.—GEOLOGICAL SECTION 
ADDRESS OF THE PRESIDENT, JOHN PuHILuirs, F.R.S. 
More than half the life of an octogenarian separates us from 
the birthday of the British Association in Yorkshire ; and few ot 
those who then helped to inaugurate a new scientific power can 
be here to-day to estimate the work which it accomplished, and 
judge of the plans which it proposes to follow in future. Would 
that we might still have with us the wise leading of Harcourt, 
and the intrepid advocacy of Sedgwick, names dear to Geology 
and always to be honoured in Yorkshire ! 
The natural sciences in general, and Geology in particular, 
have derived from the British Association some at least of the 
advantages so boldly claimed at its origin : some impediments 
have been removed from their path ; society looks with approba- 
tion on their efforts ; their progress is hailed among national 
triumphs, though achieved for the most part by voluntary 
labour; and the results of their discoveries are written in the 
prosperous annals of our native industry. . . . wa 
Turning from topics which involve industrial interests, 
to other lines of geological research, we remark how firmly 
since 4831 the great facts of rock-stratification, succession 
of life, earth-movement, and changes of oceanic areas have been 
