) Manufacture of Soda. 123 
_ surface as it accumulates, so as to leave the interior open to the 
irand carbonic acid. Water then separates from it carbonate of soda, 
and the residue consists nancinatie of sulphuret of iron. 
Kopp aids the process by an artificial supply of cold and moist 
carbonic acid, as the action of the air is very slow. This process, which 
he calis “ carbonation,” is as follows.—In a chamber, ata height of two 
and a half meters, a grating of cast-iron is placed, whose spaces are 
one and a half centimetres. ‘The earth is removed to about a depth 
of one meter. The roof of the chamber is about two and a half me- 
ters above the grating. The walls have numerous holes for the passage 
and circulation of the air. In the lower part, the carbonic acid is in- 
t The blocks of crude ferruginous soda are placed on the 
grating, on their small face; and as they crumble, the ponies “falls 
below where . ee and rapidly absorbs the carbonic acid. A 
block k of ot - requires as a maximum a space of a meter, and the 
process j Conseque 
meters | 10, will answer for 200 blocks; which will furnish more than 
50,000 =e: in 10 haar equivalent to 5000 kilograms a day. Ten 
fe 
= 
u 
‘material when ready for lixiviation should be pulverulent, __ 
gray or blackish- -gray in color, and without hard fragments. Ji is w 
— ise a. course seive to remove the stony matter: present, wlainian 
0 be lixiviated apart, taking care to reject the insoluble residue. 
The sifted cdion forms with water a lye which is clear in pri to ten 
Minutes, ho Iding a heavy deposit, with often a co ppery re 
s Th ARE NOY ts should be carried on een either vs “filtration 
oe <= sho si aceon of w: onpea uber ete Polen Vea 
nate of soda, the crystallization is often haste 
he residue, Principally sulphuret of iron, is ccsined on a 
$ surface. In this state, it alters slowly. It is dried by 
pa and made i into a brick, It is so combustible ake 
€ below 100° C. when th 
of times, in transforming common sie : nav of. sol nee 
= Oxyd of iron gradually becomes impregnated with the impuriti 
ne Common — the sulphate of soda and coa oal, and it must then be 
ga 3 yet it may be used w ‘contains even 40 p. c. of impu- 
“When the oxyd of iron coo sulphate of soda, it is necessary to 
hk o the prince of th ure for the crude soda. It has been A 
¥ experiment that : most iasenient are— ce 
Sa phate of soda, 125 vr, tees. Zs 
Peroxyd of ira al 
