126 
ON MADDER. 
On 3 trials the madder SFFP of Avignon 
gave from - - 10.00 to 10.80 
On 7 trials the madder E XTF of Avignon 
gave 10.00 
When in testing a madder by incineration, the quantity- 
operated on amounts to 5 grammes, the weight of the ash 
must be multiplied by 20 in order to bring it to 100 parts, 
and from the figure obtained 7 parts, representing the mean 
weight of ash p. c. furnished by good madder substracted ; 
the surplus then represents the proportion of earthy matters 
or of sand added by the manufacturer. Consequently, a 
madder furnishing 16.40 per cent, of ash will contain 9.40 
per cent, of foreign matter. 
2. Adulteration by Vegetable Substances. — The vege- 
table substances which are introduced into the madders are 
powders of little or no value, such as sawdust, almond shells? 
bran, the bark of the so-called pine-tree, mahogany wood' 
log-wood, sandal wood, and fir tree wood. 
The sophistication of madders by these different substan- 
ces is much more prejudicial to the dyer than that by min- 
eral substances; for besides diminishing, like the latter, the 
quantity of coloring matter of a given weight of madder, 
they also injure the dye, either by absorbing the coloring 
matter or by preventing the colors becoming so bright. 
Unfortunately the means of detecting this new kind of 
fraud are neither so rigorous nor so simple as the process 
for determining the presence of mineral matters. It is ex- 
tremely difficultto ascertain with what kind of vegetable sub- 
stance a madder has been adulterated; it is mostly only pos- 
sible to ascertain that there is a mixture. This, however, is 
the most important point, and the practical man, after all, 
only needs to know the tinctorial worth of the madder which 
he buys. 
Many methods have been proposed to determine the tinc- 
torial value of madders and the absolute quantity of the co- 
loring principal which they contain; but the greater part of 
