48 The N.Z. Journal of Science and Technology. [Jan. 
The evidences of reduction in the first stage of the experiments were 
rather meagre, hut were as follows : The material from the reduction 
furnace (1) under microscope showed a spongy structure, (2) gave off 
hydrogen when treated with acid, and (3) assayed higher in iron than the 
untreated ore. The assays were made in a small crucible in a gas-furnace.' 
Some results are shown in the table :— 
No. 
Charg 
e (Grammes). 
Yield (Grammes). 
Furnace- 
product. 
Ore. 
Lime. 
Fluor-spar. 
Charcoal. 
Iron. 
Slag. 
1 
30 
4 
10 
3 
17*5 
21 
2 
30 
3 
3 
3 
Not fused 
# . 
3 
30 
. . 
5 
5 
3 
1725 
22 
4 
30 
. . 
5 
5 
3 
1725 
22 
5 
, . 
30 
4 
10 
3 
14-6 
. . 
6 
30 
4 
10 
6 
15*8 
Experiment 1 was repeated in a larger furnace, using 15 oz. of furnace- 
product, with a similar result. The conduct of one of these dry assays 
is instructive in its bearing on the chemistry of the reduction of the sand. 
A charge of ore, charcoal, and flux heated in a closed vessel gradually up 
to melting-point yields cast iron. The time occupied was usually twenty 
minutes. This experiment alone should banish a common idea that there 
is any extreme difficulty in reducing this particular ore. 
I think I may say the experiments have proved— 
(1.) The manipulation of powdered-coal firing and electric-arc melting 
are easy. 
(2.) Smelting of ironsand can be done electrically. 
(3.) There is no difficulty in fluxing if fluor-spar be used. 
(4.) Preheating and at least some reduction can be effected very rapidly 
by the powdered-fuel flame. 
If any future work is to be done I think a furnace should be built with 
a melting-current of 200 kilowatts derived from some large electrical-power 
supply. A complete set of apparatus for wet and dry assays and for gas- 
analysis should be available, and a supply of fluor-spar. Electrodes can 
be imported or made locally. 
APPENDIX. 
Table of Constants used in the Calculation of the Reactions. 
Heat of combination per pound, in British thermal units :— 
Element. Product. 
Fe .. Fe 3 0 4 
C .. CO., 
C .. CO 
CO .. C0 2 
Specific heats : Pure iron, 0T138 ; steel, 0T217 ; CO 
CO, O, N, 0*306 + 0*000015 t.° F. 
Atomic weights : O, 16 ; C, 12 ; Fe, 56. 
Composition of air by weight: O, 23 per cent. ; N, 77 per cent. 
One kilowatt-hour = 3,410 British thermal units. 
Temperature in degrees F. by colour : Just luminous, 950 dull red, 1,250 ; cherry- 
red, 1,500 ; bright cherry-red, 1,800 ; white, 2,400 ; dazzling white, 2,700. 
Melting-points in degrees F. : Grey cast iron, 2,250; crucible steel, 2,500 ; mild 
steel, 2,900. 
2 > 
B.T.U. 
2,880 
14,540 
4,451 
4,350 
0*374 + 0*00015 t.° F. ; 
