ks am 
Hence we fee that in general weeds yield much more afhes, 
and their afhes much more falt, than woods; and that confequently 
as to falts of the vegetable alkali kind, as pot afh, pearl ath, cafhup, 
&c. neither America, Triefte, or the Northern countries, poffefs any 
advantage over us. 
adly, That of all weeds fumitary produces moft falt, and next 
to it wormwood ; but if we attend only to the quantity of falt 
in a given weight of afhes, the afhes of wormwood contain moft. 
Trifolium fibrinum alfo produces more afhes and falt than fern. 
Most of the experiments on woods were made in France by 
order of government, under the infpection of the overfeers of 
the falt-petre works ; yet are to be read with caution by thofe 
that attend to the quantity of alkali with refpe& to bleachers; for 
as tartar vitriolate (a falt ufelefs to bleachers) is as ferviceable to 
the makers of falt-petre as alkaline falts, they have conftantly 
confounded one with the other; but the experiments made on 
weeds were inftituted by perfons who carefully difcriminated thefe 
falts: 100 grains of the falt of wormwood contain but fix of 
tartar vitriolate, and 100 grains of the falt of fumitary contain 15. 
All alkaline falts, unlefs mixed with lime, contain alfo + at leaft 
of fixed air, which produces no other effect in bleaching than that 
of reftraining their ativity. 
SECTION 
