As might be expected of a substance of such vast commercial and manufacturing value, madder has undergone the most elaborate chemical researches. Its dyeing quality has been known for at least 2,000 years ,and its medicinal qualities are also men tioned by Pliny and Dioscorides. The former writer, referring to its value as a dyeing material, says: "It is a plant little known except to the sordid and avaricious, and ;his because of the large profits obtained from it, owing to its employment in dyeing wool and leather. The madder of Ravenna was, according to Dioscorides, the most !steemed. Its cultivation in Italy has never been discontinued; and under the present mlightened government it has received such an impetus that the exports of the Neapoli tan provinces alone, in one year, exceeded in value a quarter of a million sterling. It was about the beginning of the present century that the coloring matter of madder began to attract very especial attention. It had long before been noticed that cattle which used the green parts of the plant as fodder had a red color communicated to their bones, which was only removed by discontinuing this kind of food for a considerable time. This showed the coloring matter to be capable of isolation; dyers also began to suspect that the color produced was a combination of two--one red, and the other a purplish brown. But Roubiquet, a French chemist, about 1820, demonstrated that madder contains two distinct colors, capable of being isolated and used separately; lie called them alizarine and purpurine; the former, lie asserted, gave the briglat red, and the latter the purple red colors. Practically, Roubiquet's statement may be held to be
correct; but the recent and more elaborate researches of Dr. Schnuck, of Manchester, have shown the composition of madder to be very complicated indeed. At the meeting of the British association in 1861 he showed the following' chemical principles, all obtained from this remarkable root: 1. Rubianine; 2. Rubianic acid; 3. Rubianite of potash; 4. Purpurine; 5. Chlorrubian; 6. Pthalic acid; 7. Alizarine; 8. Rubiadine; 9. Chlorrubiadine; 10. Rubiafine; 11. Rubiacine; 12. Rubian; 13. Verantine; 14. Perchlor rubian; 15. Rubiagine; 16. Grape-sugar; and 17. Succine. Within the last three years, artificial alizarine has been produced, and is now extensively used by dyers. It is one of the numerous series of aniline colors.
Dyers employ madder for giving the celebrated Turkey-red to cotton goods, and for this purpose employ means for developing the alizarine; aud for purples, lilacs, and pinks, which are obtained by means of the purpurine. Manchester, Glasgow, Paisley, Alexandria, and other places on the banks of the Clyde, are the chief seats of this industry; the imports of madder into Britain in 1875 amounted to 126,152 cwt., amount ing in value to the sum of £410,993.
a painter's color, made frorn madder, by boiling it in a solution of alum, then filtering the liquid, and adding sufficient carbonate of soda to cause precipi tation of the alizarine or red coloring matter of the madder, which alone has been dissolved by the boiling solution of alum. This lake is used either as an oil or water color.