138 On Madder, and 



and mordanted cotton to each other, and also, that the 

 cloth used for the whole scale should be equally impreg- 

 nated with the mordant, and dried, cleared, and again dried 

 in the same manner. Therefore, the whole cloth must be 

 impregnated with one and the same mordant, at the same 

 time, dried by the same heat, equally washed, again dried 

 by the same heat, and then divided. If this is omitted, 

 irregular results are obtained, which proceed from the cir- 

 cumstance, that the cloth, by the absorption of the mordant, 

 acquires weight, but unequally, according to the time it is 

 allowed to hang in the air after dyeing. The different de- 

 grees of moisture of the cloth will give rise to considerable 

 irregularity. The cloth must, therefore, be employed at 

 one and the same temperature. Before placing it in the 

 vat, it should be washed in a quantity of water, and then 

 with distilled water. Pure, or distilled water must be em- 

 ployed in the dyeing. 



2. Quality of the Madder. — When madder, especially 

 that from Holland, comes in contact with the air, it absorbs 

 moisture, and becomes darker. Avignon madder and mun- 

 jeet take up much less. All examinations of madder are 

 useless, therefore, unless it is exposed to a temperature of 

 212°, and kept in glass vessels. 



Summary. — The preceding details are briefly as follow : — 



1. Madder contains three colouring matters. 



2. These three colouring matters possess different pro- 

 perties, and, therefore, their separate use will be found 

 of the greatest advantage. 



3. Madder-purple does not admit of the addition of chalk, 

 and gives, with the addition of clay, brighter dyes. 



4. Madder-red does not admit very well of the addition 

 of chalk and clay, but gives, with the assistance of these, 

 clear and pure dyes. 



5. Madder-orange is incompatible with both chalk and 

 clay. 



6. The oil mordanted cotton (oelbeizkattun) gives with 

 the half, and even less colouring matter, as complete a 

 colour, and even more complete than the common alumin- 

 ous mordanted cotton (thonbeizkattun), with the whole 

 portion of colouring matter. 



7. The aluminous mordanted cotton affords a very secure 



