I aiiftake not; is that which by Pliny is called arugo 
Salis, this it hath from the earth, and therefore it is 
again faid by Pltny^ funt ibi nitrarice in quibus et ru* 
fum exit a colare term. 
Fifthly, likt Salt Petre it will not Chryftallize. 
Sixthly, in the fire it makes no detonation. But 
in this it refembles Salt Petre , as that by the flowers 
of Sulphur is made into a Sal PrunelU, fo this if you 
drop Spirit of Sulphur upon it, flioots into Pyramidal 
Salt , that is not by the taft diftinguilhable from Sal 
Prunellce^ though its tafte before was lixiviaK 
From Sal Armoniac it may be diftinguifiied firft by 
its colour, for the iV^^ro^ is jeddifh , the other not. 
Secondly, by the texture of its parts, in Sal Armoniac 
the parts feem clofe and firmly knit together, but the 
Natron is fpongy^ and perforated. Thirdly, if mixt 
with Sal ArrtipniaCy Sal Armoniac emits the fame Spi- 
it^^^it^ do^ with quick lime. 
But I think it comes much nearer to the nature of Sal 
Armoniac, then Salt Pstre ; firft, because it is compofed 
of a Sea-falt, and an urinous Alkaly^ fecoridly, like 
Sqt' Armoniac; y whexy -d^^^ it makes it ex- 
tremel}^ cold ^ i^. nd as Franci(cus Hernande\ fays in his 
Hiftory of Mexico, it produces the fame effed: when di{- 
iolv'd in Winpj but I have not at prefent the conveni- 
ence^ of trying this , the Sfecmeni- m)w.^h^ but 
I can- 
