thofe fpecitneas which we had here grew heavier by be- 
ing expofed to the Air. 
Here it is to be noted that this jilkaly is not made fo 
by fire : I cannot therefore conchide with Helmont that 
ail Alkalies are made Inch by that element. 
The next thing to be confidered is its ieparation from 
the water in Latron , of which the Learned Dr. Hun- 
tington^ (who was at Nitria) gives us this account. 
There is a town in jEgyp t CdiWtd Nitria which gives 
name totXi^ NitrianBefert, where there is a lake called 
Latron^ taking up an Area of fix or feven acres fituate a- 
bout 30 miles Weft and by South from Terana, a Town 
lower upon the Nile than Grand Gairo, and about the 
famsdiftanceNorth -weft from ihtFyramids, ixom the bot- 
tom of thisLake this fort of Nitre calledA^^^r^?;^ arifefh to 
the top fas they do apprehend) and there by the heat of 
the Sun condenles into this kind of fubftance.That allthe 
Nitre comes from the bottom to the top I dare not affirm^ 
& fhall therefore premife fome Fhcenomena which it afford- 
ed in evaporation.before T give you myconjedrure about it, 
1 took an evaporating glafs which held about 4 ounces, 
and poured into it 2 ounces of the Nitrian Water, this I 
fet upon a fand furnace, giving it fire by degrees, as foon 
as the water was warm the particles of the Nitre began to 
fwim upon its furface in ftragling 'snd uneven numbers^ 
thefe after a while united, and at laft there arofe Salt 
fufficient to cover the whole fuperficies of the water, I 
took then a thin glafs and skim'd off this Ice, but could 
fcarce take it all off before it wasfeconded by another^ 
and thus the fait did rife fucceffivelyin films as long as 
there was any water in the glafs^thefe films had the colour 
and taft of theNitre which came fromM^;7^^,and did like 
it ferment with an Acid. And thefe are they whichby Pli- 
ny are called f^j/^/^x, and if I miftake not the fame with 
that which Herodotus fays they make their Mummy with. 
If therefore by theianguifliing heatof a digeftingfurnaces 
the nitrous particles could feparate the mfelves from the 
water^ 
