C 944 ) 
curing of old inveterate Sores, and Scrophulous Swel- 
lings, and fome, otherwife applied and qualified. The 
goodnefs of Tobacco I look on primarily confifts in the 
volatility of its Nitre : And hence the fandy Grounds 
that are moft impregnated therewith , and whofe Ni- 
trous Sale is moft volatile, for fuch Grounds are quicklieft 
fpent, yield Tobacco's that have the richeft Scent, and 
that fhortly becomes a pleafant Smoak ; whereas, in 
Tobacco that grows onftiffGround, the Salts feem more 
fix'd, and lock'd up in the Oyl, fo that whilft new, 'tis 
very heady and ftrong, and requires fome time for its 
Salts to free themfelves, and become volatile ; which it 
manifefts, by its having an Urinous Smell. The fame 
Reafon fatisfies, why Tobacco that grows on low Lands 
as far as the Salts, tho' the Plant be never overflowed 
with Salt Water, yet the Ground that feeds the Plant 
being impregnated with Salt Water , that Tobacco 
fmoaks not pteafantly, and will fcarcely keep Fire, but 
do all that a Man can, will oft go out, and gives much 
trouble in frequent lighting the Pipe, 'till after it has 
been kept fome confiderable time : which may be aP 
fign'd to the fixeder Saline Particles of the Marine Salt in 
thefe Plants, whieh require more time e're they be ren- 
der'd volatile. Here it might be worthy an Enquiry in- 
to the Nature of Filtration of Plants, fince we may 
hence gather, Particles of the Marine Salt are carried 
along with the Succus Nutritius of the Plant ; concern- 
ing which, if it were not too much to deviate from the 
-Matter in hand, I fhould offer fome Refle&ions of my 
cfwn, which the Learned Society might perhaps improve : 
for I think thence might be made many happy Conje- 
ftures as to the Virtues of Plants. So where we fee Plants, 
or Trees, of an open Pore growing low, we {hall find 
their Juice has fubtile parts : So have all Vines, whether 
the Grape Vine, or Briony, or a Smilax, or the like. 
If a Gummous Plant or Tree, that grows low, and clofe 
pored, 
