Page:History of the Royal Society.djvu/314

 found in the Troughs of Grind-stones, whereon Edge-tools have been ground. They also use Pewter for Bow-dye, Scarlet, viz. they dissolve Bars of Pewter in the Aqua-fortis they use; and make also their Dying kettles or Furnace of this Metal.

'Litharge is used by some, though acknowledged by few, for what necessary reason I cannot learn, other than to add weight unto Dyed Silk; Litharge being a Calx of Lead, one of the heaviest and most colouring Metals.

'I apprehend Antimony much used to the same purpose, though we know there be a very tingent Sulphur in their Mineral, which affordeth variety of Colour by the precipitations and other operations upon it.

'Arsenick is used in Crimson upon pretence of giving Lustre, although those who pretend not to be wanting in giving Lustre to their Silks, do utterly disown the use of Arsenick.

'Verdegrease is used by Linnen Dyers in their Yellow and Greenish Colours, although of itself it strike not deeper Colour than of pale Straws.

'Of Mineral Salts used in Dying; the chief is Allum; the very true use thereof seems to me obscure enough, notwithstanding all the Narrations I could get from Dyers about it: For I doubt,

i. Whether it be used to make common Water a fit Menstruum, wherewith to extract the Tingent particles of several hard Materials; for I find Allum to be used with such Materials as spend easy enough, as Brasil, Logwood, &c. And withal, that the Stuffs to be dyed are first boyled in Allum-Liquors, and the Allum afterwards (as they say) cleared from the said Stuff again, before any Colour at all be apply'd.

Rh