384 Miscellanies. 
This decoction enables us to dispense with the use of lees of wine 
which are no longer necessary ; and the felt is found sufficiently pre- 
pared to receive the dye. 
To make this decoction, he took half a cwt. of oak bark which was 
boiled a number of times and with different quantities of water, even 
to two ovhafts. He took afterwards eighteen pounds of this decoc- 
tion for a bath of dye, capable of employing six workmen. . 
He then added to it a little cream of tartar, with a small quantity of 
vinegar and a small portion of the lees of wine, and proceeded as usual. 
In the second bath of dye, he added only half the quantity of wine 
employed in the first. In order to obtain the best results, as in the 
case of choice felts, he found it necessary to increase the quantity of 
cream of tartar, as well as of vinegar and of lees of wine. 
It is proper to remark that, although the process of dyeing may 
be completed by a pure decoction, the mass, nevertheless, does not 
acquire the suppleness which is desired.—Recueil Industriel, Nov. 
1831. 
10. Blue coloring matter extracted from the stem of the buck-wheat. 
—(Polygonum Fagopyrum.)—A blue coloring matter, very well 
adapted to dyeing, is obtained from this plant by treating it in the fol- 
lowing manner. The stems are cut before the full maturity of the 
grain and spread upon the ground exposed"to the sun, and suffered 
to remain in this situation until the seeds drop off with ease.. When 
the grain is separated from the stems, they are thrown into heaps, 
moistened with water, and left to ferment to such a degree that. de- 
composition takes place and a blue color is developed. It is then 
formed into balls, or flat cakes, which are dried in the sun or ina 
stove. After which the balls, being boiled in water, communicate to 
it an intense blue which is not affected by vinegar or by sulphuric 
acid. This color is converted into red by alkalis, to black by pow- 
dered nut-galls, and toa very fine green by evaporation. Stuffs 
dyed blue with this preparation, in the same manner as they are dyed 
with other vegetables colors, appear very handsome and retain their 
color very well.—Recueil In. Sept. 1881. 
11. Heating of water—M. Dulong has communicated a note by 
M. Lechevalier, upon the heating of water in vessels made red- 
hot. Jt has been known for a long time, that when drops of water 
are projected upon metal raised to a white heat, that instead of un- 
