( 360 ) [July, 



VII. A RECENT TRIUMPH OF SYNTHETICAL 

 CHEMISTRY. 



It is not often that so legitimate a triumph of synthetical chemistry 

 as the artificial production of a natural substance becomes, at the 

 same time, an important national discovery, the money value of 

 which may be reckoned by millions. Such, without exaggeration, 

 it is not unlikely that the artificial production of Alizarine, the 

 colouring matter of madder, may become. 



Madder is the root of a plant belonging to the order of Bu- 

 biacew, amongst which are included some valuable plants, such as 

 the cinchona, ipecacuanha, and coffee. The madder plant is the 

 ruhia tindorum. It is estimated that its consumption reaches over 

 47,000 tons per annum, and this, at 4:51. per ton, amounts to over 

 2,000,0007. sterling, one half of which is imported to England, and 

 the payment for which (1,000,000/.) goes out of this country into 

 the pockets of foreign manufacturers. If now the essential con- 

 stituent for which madder is so valuable, its pure colouring matter, 

 can be economically prepared by chemical means from coal-tar, that 

 amount of money will naturally go into our own pockets — a not 

 unworthy reward for chemical ingenuity. 



The value of madder in dyeing and calico printing depends upon 

 the many different colours which can be dyed by its means ; thus, 

 one mordant (iron) gives purple shades, from the most delicate 

 mauve to black; with another mordant (alumina), red shades are 

 produced, from the palest pink to deep crimson, _ including the 

 brilliant and well-known Turkey red ; and by judicious admixture 

 of these mordants, combinations of all varieties of chocolate-brown 

 are produced. These colours are very permanent, whilst the high 

 price of the raw material to which they are due renders the dis- 

 covery of a substitute a problem of the highest commercial import- 

 ance. For these reasons the chemical investigations of madder have 

 been very numerous, the most valuable results having been obtained 

 by our own countryman, Dr. Schunck. This chemist found that the 

 root did not contain a colouring matter ready formed, but there was 

 in it, amongst many other bodies, a crystalline substance, which he 

 named rubianic acid. When the powdered madder is allowed to 

 stand in a moist state, or is gently heated with water in the dye- 

 beck, a peculiar fermentation sets up under the influence of a fer- 

 ment called erythrozyn, by which the rubianic acid is split up into 

 alizarine and glucose. Besides alizarine, there is another colouring 

 matter obtained from madder, called purpurine ; but as all the valu- 

 able shades and colours of madder are due to the alizarine, we need 

 only devote attention to the latter substance. 



Alizarine is a brilliant scarlet substance, which crystallizes in 



