Ll & ] 
exifts in vegetables before combuftion; not indeed in a feparate 
uncombined ftate, but united partly with the vitriolic or marine 
acids, and fometimes the nitrous, but generally and for the 
greater part with a vegetable acid or oil, with which it forms 
effential falts, as they are termed. Thefe vegetable acids and oils 
are decompofed during combuftion, and thus the alkaline part 
is fet free; but the vitriolic by contact-with inflamed matter is 
converted into fulphur, part of which unites to the free alkali, 
which protects it from combuftion, and thus forms what is 
called diver of fulphur, a product found in moft athes, efpecially 
when the air has not had free accefs to them during com- 
buftion. 
As alkaline falts are of great importance in feveral arts, the 
proportion of afhes afforded by different vegetables, and that of 
alkali by the afhes of each fort of vegetable, has of late been 
accurately attended to, I fhall here prefent the beft authenticated 
refults of the experiments made with this view. 
One thoufand weight of the following vegetables, perfectly 
dry and burned ina clean chimney and open fire, afforded the 
quantity of afhes and faline matter, exhibited in the annexed 
table: 
One 
