362 SUPPLEMENT 
stances on which they feed. Those which live in mud, or 
among the alge, and feed thereon, are in very little estima- 
tion. Those of the coasts, which are gathered by the sea-side, 
are better, though the colour which they furnish is lighter and 
more clear. Another variety, which is called gravelly, from 
the gravel-beds of the sea, where it is found, is extremely 
proper for the conchylian colours ; but the best for the purple 
colours is the dialutensis, that is, the one which finds its sub- 
sistence on different kinds of soil or strata. 
“ The purpure are taken with small nets, which are cast 
into the deep sea. Bivalve shell-fish are used by way of 
bait, which can open and close, or mussels, which, half-dead, 
are reanimated as soon as they are restored to the sea, and 
half open their shell. The purpure, eager to devour these, 
attack and thrust their tongue into them. But soon stimu- 
lated by this sting, the mussels close their shell, and retain 
the purpurz, so that, victims of their avidity, the latter are 
carried off still suspended to their prey. The most advan- 
tageous season for this fishing, is after the rising of the lesser 
dog-star, or before the spring, because when the purpure 
have spawned, their juices are too liquid. But the workmen 
are ignorant of this, although it is very essential. 
** In employing the purpure for dying, the artists begin by 
removing the vein already mentioned, and adding to one 
hundred pounds of this substance, twenty ounces of salt. 
The whole is allowed to macerate for three days exactly. Itis 
boiled in a leaden cauldron, until greatly reduced. A moderate 
heat is then kept up by means of a long stove; after which, 
the flesh which necessarily remained attached to the veins, 
being skinned off, and the tincture being completely liquified 
on the tenth day, and afterwards strained, the wool is plunged 
into it. They continue to keep it warm until the desired 
point has been ascertained. A lively red tint is less valued 
than a blackish red. The wool is left to steep for five hour? 
