M. Decaisne on the Root of the Madder. 273 



all that I have been able to ascertain, and the simple yet stri- 

 king fact of the absence of the red colouring principle until 

 the root has been pulverized, seems to have been unknown to 

 the present day. 



Still this observation, originally made by M. Chevreul, is 

 stated in a paper by M. Kcechlin, inserted in the Bulletins de 

 la Societe de Mulhausen, vol. i. No. 3, in the following words : 

 u By compressing the fleshy part of the fresh root an acid 

 liquid is obtained, which, originally yellow, turns red when 

 exposed to the air. This liquid, applied to a cloth that has re- 

 ceived the mordant of acetate of alumina, produces a bright 

 red, which by soap changes to a dullish rose. It tinges am- 

 monia purple and concentrated sulphuric acid red, and an ad- 

 dition of water to the tinged acid precipitates the colouring 

 substance. These experiments seem to prove that the colour- 

 ing substance is in a state of solution in this fluid. 



" The stalk of madder and its root, whether whole or the 

 woody and fleshy parts individually, have been used to dye 

 samples of the same size and printed with mordants red, pink, 

 violet and black, and the result is that the fleshy part contains 

 almost exclusively the colouring substance, the woody portion 

 possessing no more of it than do the stalks of this plant. 



" These various parts of the madder, when used fresh, have 

 invariably produced much richer hues than the same parts if 

 previously dried, although this process of desiccation had not 

 diminished their weight. And however numerous were the 

 experiments, their result was always the same. 



u When the root is examined with the microscope, no trace 

 of separate colouring substance is discernible; the woody part 

 is very porous, as in all vegetables; and the fleshy portion seems 

 composed of mucilaginous liquid parts, inclosed in a net-work 

 of woody filaments, without offering any trace of porosity. 



u The £ Alizaris } of Avignon are composed of stems and 

 roots ; the former having been covered up with earth, assume 

 the appearance of roots without acquiring their dyeing virtues, 

 so that the cultivator who thus increases the quantity of his 

 produce materially lessens its value. For these stems, con- 

 taining very little colouring principle, this plan only tends to 

 adulterate the madder, of which the quality thus depends on 



Ann. Nat. Hist, Vol.1. No, 4. June 1838. t 



