642 NOTES AND ABSTEACTS IN CHEMISTRY AND PHARMACY. 
The Artificial Production of Alizarine. 
Much attention from the commercial no less than from the scientific portion 
of the community is just now attracted by this remarkable discovery, the sub¬ 
ject of no less than three patents. At the last meeting of the Chemical Society, 
Mr. W. H. Perkin, one of the patentees, and so well known from his connection 
with aniline dyes, gave an account of the processes he adopts, and the products 
he obtains, in the manufacture of alizarine, several tons of which have already 
been artificially produced. 
The starting-point is anthracene , a hydrocarbon extracted from coal-tar, but 
which has hitherto presented little interest. 
Its formula is C 14 H 10 ; by the action of agents of oxidation, such as mercu¬ 
rous nitrate or peroxide of manganese, it is converted into oxanthracene or 
anthraquinone, C 14 H s 0 2 . The next part of the process consists in heating the 
oxanthracene, with concentrated or fuming sulphuric acid, until a portion of 
the mixture, when added to water, perfectly dissolves *, the resulting product is 
then diluted with water, and, having been freed from excess of acid by addition 
of carbonate of lime or baryta, and the precipitated sulphate filtered off, caustic 
soda or other alkali is added to it in considerable excess, and until the liquid is 
very strongly alkaline; the solution is then concentrated, and heated up to a 
temperature of about 200° or 240° C. The product then changes to a blue or 
bluish-violet colour. The temperature is maintained until the colour of the 
product ceases to become more intense. The coloured mass is then dissolved in 
water, and acidulated with hydrochloric or other acid, which causes the solution 
to become yellow, and a yellowish precipitate to form. This precipitate is col¬ 
lected upon a filter washed with water, and is then in a suitable condition for 
use in dyeing and printing in the same manner as preparations of madder. It 
is, in fact, alizarine, C 14 H g 0 4 . 
Mr. Perkin showed abundantly that the substance thus obtained is really 
alizarine, and identical in properties with the natural principle procured from 
madder. Comparisons of its reactions under the influence of chemical agents, 
of the solutions it gives with alkalies, and of the absorption bands introduced 
into the spectrum by these solutions, with the appearances of the natural aliza¬ 
rine under similar circumstances, prove this identity. 
One great difficulty yet to be overcome before the artificial alizarine can be¬ 
come a commercial article is the difficulty of obtaining anthracene in large 
quantities ; and this question is of some importance to us, England being the 
great tar-producing country. Anthracene does not appear to exist in greater 
proportion than one part in a thousand of tar, and is only liberated or produced 
during the latter part of the distillation of the tar. 
Even when the heavy coal oils are obtained the separation of the small quan¬ 
tity of anthracene they contain, and its purification for use, according to the 
patents, will yet require much time and research. Dr. Crace Calvert, speaking 
on the subject at Manchester, stated that the purest product he had been able 
to obtain on a moderate commercial scale contained when cold-pressed about 
40 per cent., and when hot-pressed about 70 per cent, of anthracene. 
One of the chief difficulties in its preparation is the fact of its great solubility 
in its liquid homologues at a moderate temperature. Thus, an oil at 40° or 
45° F. will yield a comparatively large quantity of anthracene by filtration ; 
but if its temperature be raised to 70° or 80° F. the anthracene will be com¬ 
pletely dissolved. 
Should the process be commercially successful, it is likely to influence the 
madder trade very considerably. 
