[ 59 } 
“ The vegetable alkali has a ftronger affinity to 
« the acid fpirits of vitriol^ nitre, and marine fait, 
“ than the foffil j” for 
(r) If the common alkali be added to a faturated 
folution of Glauber’s fait in water,, the fpirit of vi- 
triol will leave the natron-; and uniting itfelf with 
the vegetable fixed fait will form vitriolated tartar ; 
which being of difficult folution, much of it will 
cryfiallize and .fall to the bottom, while the natron, 
robbed of the vitriolic acid, remains difiblved toge- 
ther with a fmall portion of the vitriolated tartar. 
(2) Gr. 1 66 of quadrangular nitre were difiblved 
by heat in a folution containing gr. 138 of pearl- 
affies. On cooling, there ffiot fome cryftals of com- 
mon nitre, the nitrous acid having left the foffil al- 
kali, which is the bafe of quadrangular nitre, to join 
itfelf with the pearl-aflies. 
(3) Gr. 500 of fal-gem, which feemed quite free 
from fal catharticus amarus, were difiblved by heat 
in a folution of gr. 654 of pearl-affies. There ffiot 
a confiderable quantity of fal fylvii mixed with foffil 
alkali, which had been expelled by the pearl-affies 
from the marine acid. 
Thefe experiments were made and communicated 
to me by the Hon. Henry Cavendifli. 
Befides the properties, which have been mentioned, 
the natives of the Canary iflands have found out, that 
they can make matches by dipping paper or tow in 
a flrong folution of natron, which will then burn, 
except that they do not fparkle, almofl; as well as if 
they had been dipped in a folution of nitre, though 
upon trial no nitre appears to be mixed with it. The 
fait of barilla and kelp 1 find, by experience, to have 
I 2 this 
