( 575 ) 
Cryftals.j tranfparent, and like the S^jI Mirahile: But 
as this Salt, by this Method, is not fufficiently fatiated 
with the 01, VitrioL(if they ufe any) fo it is eahly dif- 
covered by the 01. Vitriol, which will readily ferment 
with it whereas it has no ElFed on the other Sal Mi- 
rahile made as above. 
By the AlTiftance of my ingenious Friend, Robert Cay., 
Efq^ at Newcajile., I have received the feveral Shoot- 
ings of Salts from their Bittern, as alfofome of the Bit- 
^ tern it felf ^ from >each of which I have obtain’d a pure 
Sal Catharticum, as * alfo the like kind of third Salt, 
as mention’d from the Lemington Bittern, The Method 
I took in doing it is agreeable to that I have already 
mention’d, and many Years ago try’d at the Salt-Works 
near Portfmoutb, It is by Mr. Cay that I am inform’d, 
they fometimes boyl their Bittern without letting it 
Hand any time to (hoot of itfelf. The Difference is not 
very material. 
If this Account be intelligible, what the Sal Ca- 
tharticum is will no longer be a Myftery. And the 
next Thing worth the enquiring into will be, whether 
this Salt deferves the Refiedions, that have difeouraged 
the Prefer ip don of it } And why it may not pafs for a 
Salt as excellent in its Kind, and be of the fame Na- 
ture, and have the fame Properties, as that produc’d 
from the Epfom, or any other bitter purging Springs. 
And in order to prove it to be fo, I lhall give a very 
Ihort Abftrad of what Dr. Grew fays of his Salt, and 
then pbferve how nearly the two Accounts agree. 
The Dodor in hisTreatife de Natura SalisCathartici 
Amari, Chap, 2 . fays, that in the Evaporation of any 
of the bitter Purging Waters, they yield a Cremor at 
Top, as alfo a Sediment, both together weighing 6, 8, 
or about lo Drams,, from a Gallon of Watery and 
that the lefler Part of this Sediment is, in Subftance, 
the 
