800 CHYMISTRY APPLIED TO AGRICULTURE. 



beds must be turned over, and, if this be not sufficient, the 

 whole must be again ground in the mill. 



After fermentation, the paste seldom appears of a uni- 

 form texture, and there will be found in it some remains of 

 nerves which are visible to the eye ; for this reason it 

 is subjected to a second grinding, after which it is ready 

 to be made into cakes ; this is done by filling round 

 wooden moulds with it, or by forming loaves four or five 

 inches in diameter, and eight or ten in height, and usually 

 weighing about three pounds and a quarter. In the south 

 of France the moulds are usually much smaller, and the 

 loaves of woad, known by the name of shells^ weigh but 

 little more than one pound. These cakes should, when 

 broken, appear of a violet color, and exhale a good odor. 



The cakes are placed upon hurdles, and carried to a dry 

 and airy place to harden. 



In most countries the cakes are sold in this state to the 

 dyers, who make use of them either to heighten their 

 woad dyes, or for dying by themselves a soft blue ; but in 

 general they are made to undergo another process, by 

 which they are improved ; this is called refining. This 

 last operation is, however, seldom performed by the manu- 

 facturers, but by the dealers to whom they are sold in large 

 quantities ; the reason of this is, that the process of refining 

 can be performed advantageously only on large masses, 

 and the proprietor of the fields for cultivating woad has 

 only the product of his harvest, and the conveniences ne- 

 cessary for making it into cakes. 



For refining the woad cakes, it is necessary that they 

 should either be ground in a mill or broken in pieces with 

 an axe ; the fragments are made into beds about four feet 

 high, and sprinkled either with water, or, what is prefera- 

 ble, with the juice of the leaves ; heat is developed in a short 

 time, and a violent fermentation takes place. At the end 

 of six days, the bed is turned, so as to bring the interior or 

 under portion upon the top ; this is watered in the same 

 manner, and, five or six days after, the bed is again made 

 over with the same care. These operations are renewed 

 at short intervals, till the mass, having ceased to ferment, 

 becomes cold ; in this state all the animal and vegetable 

 portions, with the exception of the indigo, are decomposed, 

 and it is now sold to the dyers to the greatest advantage. 



The mode of making woad cakes here described, is un- 

 doubtedly the most perfect one, but it is not everywhere 



