333 
Rowley- rag-hone and the Toad-hone. 
Pure filiceous earth - 47 \ 
Pure clay, free from fixable air 32I 
Iron in a calciform hate - 20 
100 
From this view of the component parts of this hone, it is 
not improbable, that it might advantageouflv be ufed as a flux 
for calcareous iron ores. The makers of iron are acquainted 
with fuch ores ; but never could work them to advantage, for 
want of a cheap and efficacious flux. 
TOAD-STONE. 
FROM Derby (hire ; fent to me by Mr. whitehurst, who 
has fo fully and fo accurately deferibed the mode of its {Ratifi- 
cation, that it is needlefs to enlarge upon that fubjedh 
MORE OBVIOUS PROPERTIES. 
Of a dark brownifh grey, a granulated texture ; with feveral 
cavities filled with cryhalhzed {par. It does not hiikt fnc 
with heel. It melts to a black glals. 
E' X P E R r M E N T 3. 
A. ioo parts rubbed to an extremely fine powder in a china 
mortar, and boiled in marine acid ; the folution was decanted : 
the undiffolved part, after proper walhing and drying, weighed 
7 1 - 
B. The 
