On Scowering different Kinds of Stuff. abt 
- our. dyfenteries and fevers; nor do thefe lefs deferve the 
title than the fevers of Smyrna, Cairo, and Conftantinople, 
which refemble them in their origin, their varieties of pre- 
valence and degree, their appearance and difappearance, and 
which would, in all probability, yield to the fame regimen 
and iencdies. 
= 
VIII. Objervations on the Art of Scowering different Kinds 
of Stuff. By C. CHAPTAL%. 
Tus art fuppofes, rft, a knowledge of the different fub- 
ftances capable of ftaining any kind of cloth; ad, of the 
- fubftances to which recourfe mutt be had in order to make 
thofe depofited on the fiuff to difappear ; 3d, a knowledge: 
_ of the effects produced on colours by thofe re-agents which 
it may be neceflary to employ to deftroy flains ; 4th, a know- 
ledge of the manner in which the cloth is affected by thofe 
re-agents; 5th, of the art of reftoring a colour changed of 
faded.—Of thofe bodies which occafion fpots on different 
kinds of cloth, fome are eafily diftinguifhed by their appear- 
ance, fuch as greafy fubftances ; but others have more com- 
plex effects, fuch as acids, alkalies, perfpired matter, fruits, 
urine,.&c, Acids redden black, fawn, violet and puce- 
colour, and every fhade communicated with orchilla-weed, 
iron, aftringents, and every blue except indigo and pruffian 
blue. They render the yellows paler, except that of arnatto, 
which they change into orange. 
Alkalies change to violet the reds produced by Brazil wood, 
logwood, and cochineal. They render the greens on woollen 
‘cloth yellowith, make yellow brownith, and change the yel- 
; Jow produced by arnatto to aurora. Perfpired matter produces 
the fame effects as alkalies. 
When the {pots are produced by fimple bodies on ftuffs, 
it is ealy to remoye them by the means already known. 
Greafy fubftances are removed by alkalies, foaps, the yolk of 
eggs, fat earths; oxyds of iron, by the nitric and oxalic acids; 
_ acids by alkalies, and reciprocally. Stains of fruit on sahite 
* From the Bulletin des Sciences, Vol. LI. No, 4. 
ftufls 
