PREPARATION OF WOAD CAKES. 301 



practised. At Genoa they do not refine them ; in the de- 

 partment of Calvados, and upon the Rhine, they pile up 

 the leaves without grinding them ; and they mould the 

 cakes as soon as the division of the mass will allow of this 

 operation. 



It is necessary to observe, that an immense variety in 

 the quality of the cakes is produced, not only by the na- 

 ture of the soil and climate, but also by the difference 

 of seasons, and by the care bestowed upon the cultivation 

 of the plant and the gathering of the leaves; and from 

 these circumstances arises the different estimation in 

 which they are held in commerce, and consequently the 

 various prices at which they are sold. The leaves of 

 "woad yield about ^ their weight of good cakes; these, 

 when used with indigo to form dyes for producing a 

 permanent blue color, serve not only to facilitate fermenta- 

 tion, but add the indigo which they contain, to that which is 

 brought from India, and thus render the dye less expensive. 



The cakes, especially those that have been refined, 

 contain alone a sufficient quantity of indigo to give to 

 cloth all the shades of blue, which can be procured from 

 the imported material. M. Giobert states, that M. Alex- 

 ander Mazera, in the presence of several skilful dyers and 

 manufacturers, and of the commissaries of the Academy 

 of Turin, colored with the cakes four pieces of fine cloth 

 of four different shades, and they were judged to be at 

 least equal in brilliancy and durability to those obtained 

 from the best Bengal indigo. 



M. de Puymaurin has published an account of a process 

 by which the inhabitants of the island of Corfu color, with 

 the leaves of the isatis, the woollen stuffs of which they 

 make their clothing. The practice with them is to cut 

 the leaves when the plant is in flower, and, after carefully 

 drawing out all the nerves, to reduce them to paste in a 

 mortar ; this paste is dried in the sun, and when it is to 

 be used for coloring, is placed in a bucket and moistened 

 with water; the mixture gradually heats, and at length 

 ferments strongly ; water and a little weak ley of ashes 

 is added, and the paste undergoes the putrid fermentation. 

 Into this composition the cloth which is to be colored is 

 plunged, and allowed to remain eight days, turning it from 

 time to time ; in this way it acquires a deep and lasting 

 blue. The ease with which this process is executed, 

 would render it very useful in farmers' families. 

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