Before I class Iron ores in this respect, I would observe^ 
that it is necessary to bring the iron into a metalline state 
which is done by charcoal and heat. Also, that when 
brought into a metalline state, it will not fall down and 
unite in one mass, but be enveloped in separate particles 
among the coals, unless the coals and the earths of the 
stone, are brought into fusion, and made into a glass so 
thin that the particles of metal by their superior weight, 
will fall through them. This is done by knowing in 
what way the earths can be so mixed, as to be brought 
into thin fusion, by the usual fire of a furnace. 
On the jinxes of Iron ores . 
The principles on which all earthy fluxes depend, is, 
that no earth is fusible alone — -that argillaceous and sili- 
ceous earths together are infusible— that argillaceous and 
magnesian earths together are infusible — -that silicious 
earths and magnesian earths together are infusible — but 
that when lime or limestone (calcareous earth) is added 
to any mixture of the other two, they will run into a glass, 
which will be thin and fluid with the same application of 
heat, in proportion to the judicious mixture of the several 
earths. M. D’Arcet, a French chemist, made this experi- 
ment : He put into one crucible a round marble of clay* 
into another a ball of the same size of quartzose or silici- 
ous sandstone, into another, a ball of the same size of 
chalk ; and exposed them to a violent heat in the same 
furnace for the same length of time. They were all un- 
charged, except where the chalk ball had touched the cru- 
cible ; in that place, there was the appearance of fusion* 
He put all three balls together, first reducing them to 
pow der and mixing them. In a short time the same fur-- 
nace melted them into a transparent glass. 
Moreover the experiments of Mr. Kirwan have ascer* 
tained 
