64 
Iron, 
lure with which the iron is combined, that the same fecipd 
can seldom be applied to more than one variety. As 
iron-stones are more defined, and their treatment prescri- 
bed by more certain rule, a knowledge of them will soon 
lead to a just comprehension of the primary ores ; a se- 
cond experiment, therefore, with any of them, will be suf- 
ficient to point out the necessary proportions for obtaining 
in the next assay carbonated crude iron. In one collect 
tion of Norwegian ores I found the following variety;*— 
No. 1. 
No. 2; 
No. 3. 
No. 4. 
No. 5. 
No. 6. 
« ns 
- 21 
- 35 
- 47 
- 55 - 
63 iron 
1^17 
- 16 
- 19 
- 11 
- 24 - 
19 volatile 
(J55 
- 63 
- 46 
- 42 
- 21 - 
18 earths 
100 
100 
100 
100 
100 
100 
This simple table will shew plainly how necessary it is 
to accommodate the flux to the variety of the ore. If 
from this collection you wish to obtain carbonated regu- 
!us, it is obvious that, in order to saturate them equally, 
the iron contained in No. 3 ought to be presented with 
double the quantity of carbon necessary to carbonate No. 
I ; No. 5 with a triple quantity ; that of No. 6 with more 
than 3 and a half : and as I have proved that this effect 
will be chiefly produced with the use of a calcareous earth ? 
it will at once be conceived how far this substance is to be 
used as the instrument of alteration. 
In the recipes adduced in this and the preceding paper, 
I have always noted charcoal as a constit uent of each mix- 
ture. Since I discovered that the contact of calcar com 
earths conveyed carhonation to the metal 3 by the decompose 
tion of the carbonic acid, , I have reduced the proportion 
of charcoal commonly used in the flux, and have, in the 
treatment of most iron-stones, even abandoned it altoge- 
ther : however, as my experiments have not yet extended 
universally to primary ores, I have, in the mean time, re- 
tained it as a constituent part of the solvent. 
