in bleaching Linen . 241 
bleachers, that, by proper management, the dan¬ 
ger was next to none. 
According to the ftrength of the acids they 
muft be mixed with water, fometimes, to feven 
hundred times their bulk. 
The nitrous acid, being the moft corrofive,. 
and moft expenfive, has not been ufed. 
The vitriolic acid is that which has univer- 
fally been employed: not becaufe it is prefer¬ 
able to the muriatic acid, but becaufe it was to 
be bought in large quantities, and at a fmall 
expence. 
The muriatic acid being now fold nearly as 
cheap as the vitriolic, and anfwering in a fupe- 
rior degree, will, in a fhorc time, I.am convinced, 
be generally adopted by bleachers. 
As 1 muft confefs my ignorance in the art of 
bleaching, it may feem prefumptuous in me to 
hazard a conje&ure concerning the manner in 
which acids a£t in whitening cloth j but it feems 
probable, that alkaline falts, which are ufed in 
walking out the oil and glutinous parts of flax, 
on which the green colour depends, depofite an 
earth, in the pores of the cloth. As it is known 
that acids will alfo diflfolve the earthy parts of ve¬ 
getables, that acid Ihould be preferred, which will 
keep earthy particles fufpended in water. The 
vitriolic, therefore, is not fo proper j becaufe, with 
earthy fubftances, it forms immediately a felenite; 
Vol. I. R a fub- 
