1835.] Calico- Printing. 163 



The cloth is impregnated with the aluminous mordant 

 which is discharged on the white portions by the method just 

 described. It is then dyed with madder in the usual way, 

 only a quantity of logwood is mixed with the madder. This 

 logwood changes the madder- red to brown, and produces the 

 colour observable in the accompanying piece of calico. 



15. Cochineal Pink. 



The cloth in this case also is impregnated with the same 

 aluminous mordant, and the white portions are discharged 

 by means of citric acid, in the way described in a former 

 paragraph. It is then dyed in cochineal, which communi- 

 cates the beautiful pink observable in this specimen of 

 cloth. 



For this beautiful dye we are indebted to America. 

 Cochineal is the name given to a small insect which 

 inhabits the cactus coccinilifera, and three or four other 

 species of cactus, on which it remains immoveable, deriving 

 its nourishment from the juices of the plant. It is a native 

 of Mexico, and had been employed by the natives as a red 

 dye. When the Spaniards entered that country in 1518, it 

 drew their attention, and in 1523 Cortes received orders 

 from the Court of Spain to procure as great a quantity of it 

 as possible. The earlier Spanish writers describe cochineal 

 as an insect ; but it came afterwards to be considered as the 

 seed of a plant ; and this erroneous notion was not fully 

 cleared away till about the middle of the eighteenth century. 



The red principle in cochineal may be extracted by means 

 of alcohol. It has a fine purple colour, and may be obtained 

 in small crystals. It melts at 122°, and when heated, is 



m 2 



