16 _ Strictures.on Mr. Collier’s 
Dhal-Grube is powerfully obedient to the magnet, yet yields, 
only 21. pounds in 100 of the ore. 
Admitting, however, that rich ores make a fuperior qua- 
lity of iron, why then are not fuch qualities produced from 
the ores found in Cumberland or Lancafhire, fince the hz- 
matites and kidney of the former are as rich in iron. as the 
fineft Swedifh ores? Mr. Collier fhould have. diftmguithed, 
too, between the argillaceous ores, commonly called iron- 
ftanes, found in ftrata more or lefs inclined to, the horizon, 
fo univerfally diffufed and {melted; and thofe of Cumber- 
land and Lancafhire, formed into knobs, or in vertical ftrata, 
which are only partially ufed. The former are the only ores 
ufed in quantity to produce grey crude iron, and. contain of 
iron from 18 to 42 pounds in 100: .the latter are ufed in 
great part for fabricating the inferior qualities of crude iron, 
fuch as fhip ballaft, forge pigs, &c. &c.. The Cumberland. 
ore exhibits a variety of qualities and proportions of iron: 
The fine Hzematites ore yields of iron 68 to 7olbs. per 100, 
Kidney - - - , 60 to 63. 
Common - - + 53 to 6o. 
Lancafliire ore will be found to, yield, upon an average, 
57, pounds iron in 100, 
I fhould be apt to afcribe the general fuperiority of foreign 
iron over Britith, folely to the ufe of wood charcoal in all 
the ftages of the operation ; and the fuperiority of the indi- 
yidual fabrics over each other, to the native excellence of 
the iron contained in the ore. It is well known that the 
Swedifh marks of bar iron, () and O ©, are manufac- 
tured from a peculiar ore, found in the mine of Danamora ; 
and that no other Swedith ores yield fuch a quality of iron, 
even when manufactured in the fame manner and with the 
fame fuel. It is the fame in Siberia, where the old and new 
fable fabrics have gained, by the native fuperiority of the 
iron contained in the ore, an excellence little inferior to. the 
principal Swedifh marks, From numerous experiments I 
am convinced, that the iron ‘contained i in our iron-ftones, or 
a hho AG 
7 ; sales: argul- 
