PREPARATION OF WOAD CAKES. 299 



must be taken not to injure the stalks or tops of the plants j 

 the cuttings may be repeated once in six or eight days, so 

 as not to allow time for the quality of the leaves to de- 

 generate. A mixture of the leaves of strange plants, and 

 of the bastard woad, with those of the isatis tinctoria, must 

 be carefully avoided. 



The leaves, when gathered, are put into baskets and 

 conveyed to the work-shop in which the manufacture of 

 woad cakes is carried on ; when they have begun to wither, 

 they are ground between two mill-stones equally chan- 

 nelled ; the bruised substance being frequently stirred with 

 a shovel, and the grinding continued till the nerves of the 

 leaves can no longer be perceived by the eye. All the 

 juice which flows out during grinding, is carefully pre- 

 served to moisten the paste with when it is fermenting. 



The paste is carried under a shed, the ground of which 

 is a little sloping, and paved with cemented stones, in 

 which are little channels for conveying into a reservoir 

 the juice which flows out. Under the highest part of the 

 shed is formed a bed of the paste three or four feet in length ; 

 to render this bed as compact as possible, it is beaten down 

 with heavy pieces of wood. Fermentation commences in 

 a short time, the mass swells and cracks, and there flows 

 out from it a black liquor, which is conducted into the res- 

 ervoir by the channels in the pavement. In some manu- 

 factories, this liquor is allowed to run off upon the ground 

 without the shed; but the odor which it diff'uses in this 

 case is very offensive. 



Whilst fermentation is going on, attention is paid to re- 

 uniting the mass when it cracks, and to moistening it either 

 with urine, or with the juice which flowed from it when 

 between the mill-stones. 



After the paste has fermented well for three or four 

 days, the mass is again beaten down, and this operation is 

 renewed several times during the twenty or thirty days that 

 the fermentation lasts ; the paste being in the intervals 

 moistened with the juice, and the surface of it united. 



In a cold season, or when the leaves are poor and dry, 

 fermentation will not be completed in a month ; in Italy 

 they often allow four months for it, and sometimes the bed 

 is not removed till the following spring. 



There is a kind of worm which often takes possession 

 of these beds, and sometimes in such numbers as to de- 

 vour all the indigo contained in them; in this case the 



