Stuffs for Dyeing. —Yellow Dye. 99 
manner, gives conftantly the colour which denotes the pre- 
fence of that oxyd. This precipitate is not without a little 
iron, which it receives, as I believe, from the pruffiat of pote 
afh. Then put nitric acid over the refiduum of the afhes, 
and it will take from them the iron, which may be proved 
alfo by the pruffiat. Then fearch for the different earths, 
which may be difcoyered by the common means.- The 
afhes of the pine, calendula, vine, green oak, and fig-tree, 
contain manganefe. The afhes of the fig-tree are almoft all 
filiceous; the afhes of barilla do not contain an atom of it, 
but iron in great quantity, magnefia, &c. 
PREPARATION OF STUFFS FOR DYEING. 
A letter from Van Mons to Brugnatelli, printed in the 
92d number of the Annales de Chimie, contains a ufeful 
hint-on this fubjeét. He expreffes himtelf as follows: 
** The memoir, read by Giobert tothe Academy of Turin 
on the animalifation of flax and cotton, induces me to men- 
tion a circumftance which ought to have led me to the dif- 
cavery of this animalifation long ago, had I paid proper at- 
tention to it at the time, I had. caufed fome oyfter-fhells to 
be boiled with pot-afh.and lime, in order to whiten them for 
fome pharmaceutical purpofes 5 and I employed _the ley pro- 
duced by that operation, to bleach the linen cloths ufed to 
firain the decoctions. My pupils made me afterwards ob- 
ferve, that thefe pieces of cloth were ftrongly dyed when any 
fubftances were paffed through them, the colour in which 
might have been carried off by merely wathing in cold water.” 
YELLOW DYE FROM 4 SPECIES OF MUSHROOM, 
Among the different kinds of mufhrooms, capable of pro- 
ducing tively and durable dyes, none is more worthy of no- 
tice than the Boletus birfutus of Bulliard, from which C, 
Lafteyrie has extracted 4 bright, fhining, and very durable 
yellow dye. This pretty large mufhroom grows commonly 
on walnut and apple-trees. Its colouring-matter-is con- 
tained in abundance, not only in the tubular part, but alfo 
ip the parenchyma of the body of the muthroom, In order 
O32 to 
