According to Schutzenberger, the most recent and highest French authority, the dimensions of the pastel vat are about 6½ feet in diameter, by 9 in depth. 100 kilograms (221 lbs.) of pastel, in balls, is placed in the vat, which is then filled with boiling water. To this is added 10 kilograms (22 lbs.) of madder, 3 to 4 kilograms (about 6½ to 8¾ lbs.) of bran, and 4 kilograms of quicklime, which has been slacked, and in the form of a _bouilli_. Sometimes weld is also added. After three hours of rest, the vat is well raked, and the operation is repeated every three hours. There is gradually developed a characteristic ammoniacal vapor, and a blue scum, with veins of deeper blue, forms on the surface; and the liquid, when agitated in the air, rapidly becomes blue. These symptoms indicate the dissolution of the indigotine of the woad; then there is added 10 kilograms (22 lbs.) of indigo which has been previously ground in water, and the vat is stirred. If the fermentation appears to be proceeding too actively, which is recognized by the disengagement of gases, it is checked by the addition of a proper dose of lime. On the other hand, the fermentation is made more active by increasing the dose of bran. The first dyes are not so good as those subsequently obtained, as the woad absorbs from the bath certain brown or yellow materials, kept in solution, and furnished as well by the pastel and madder as by the indigo itself. 100 kilograms of wool require from 8 to 12 kilograms of indigo. The vat is kept up by successive additions of indigo and lime, made in the evening. Another kind of pastel vat, prepared much like the last, receives an addition of a dose of potash. M. de Kæppelin describes it as the one at present in general use in France. Into a vat containing from 3,000 to 4,000 litres (791 to 1,055 gallons) there is placed 75 kilograms (166 lbs.) of pastel in loaves, or which has undergone a kind of fermentation; or, what is preferable, 80 to 100 kilograms (176 to 221 lbs.) of pastel or woad gathered without fermentation, and 10 kilograms (22 lbs.) of indigo, ground to a paste with water. This mixture is well stirred, and there is added 4 kilograms (about 9 lbs.) of Avignon madder, and the same quantity of carbonate of potash. After the vat has been well raked there is added 2 kilograms (4½ lbs.) of slacked lime, and some pails of bran. The vat is well covered, either with a wooden lid, or woollen cloths. The fermentation is allowed to proceed, and after five or six hours the vat is uncovered and raked with much care for half an hour. This operation is repeated every three hours, until it is recognized that the indigo is well dissolved. In this case the bath ought to be of a beautiful yellow color, and be covered with a light blue irised film, veined with yellow at the least movement given to the liquid. If the fermentation proceeds too rapidly, a little lime is added to moderate it.