Madder with Starch, Flour and Bran, 453 



itself nar by the proportion of 3 bran to 1 madder, it is 

 obvious that bran does not receive its efficacy in dyeing 

 from the starch contained in it, but from some other con- 

 stituent. 



Wheat flour acts with as little advantage but less disad- 

 vantageously than bran. In the proportion of 1 lb. flour 

 to 6 lbs. madder and 6 lbs. mordanted cloth, the colour is 

 only a little more red than madder-red dyed without an 

 adjunct. When the quantity of flour is increased to 3 lbs. 

 it acquires a similar action to the bran, but which is not 

 stronger than is obtained by 4 lbs. bran, 6 lbs. madder, and 

 6 lbs. mordanted cloth. It follows, therefore, from this, 

 that the action of the bran in madder dyeing, is not to be 

 ascribed to the flour which is still contained in the wheat 

 bran. These results led Runge to make the inquiry, to 

 which of the constituents of bran does it owe its well known 

 property, since it is neither due to the starch nor to the 

 flour containing gum. He first examined the husks of the 

 bran. To obtain these in a state of purity, wheat bran was 

 washed so long with cold water as it continues to dissolve 

 and remove starch or flour, and then the remaining brown 

 coloured husks were added to the madder solution. It was 

 then found that the husks of bran had a stronger action 

 upon avignon madder than the same quantity of unwashed 

 bran. 



From what was said formerly, the action of bran appeared 

 very doubtful. It seemed to redden brownish madder-red, 

 and to distribute the madder-red over a greater surface. By 

 the first action of the bran, a clearer red is obtained than 

 usual ; but the second, the production of a very saturated 

 red is prevented. In respect to the husks of bran, they 

 afiect a distributive action. They equally hold the colour- 

 ing matter, and render it difficult to combine with the 

 mordanted cotton. The following experiment shews this : 



In a solution consisting of 12 Avignon madder, and the 

 husks of 36 bran, 3 of mordanted cloth were successively 

 dyed three times with an increasing, and at a boiling 

 temperature. 



The result of the first dyeing with 3 cloth was a clear 

 red not half so dark as the first dyeing with madder and 

 bran, noticed in a former part of this treatise. In the 



