ON THE CHEMICAL MANUFACTURES OF THE NORTHERN DISTRICTS. 707 
and the whole of the vapour or gas which escapes passes through a 12-inch 
pipe always open to view. At present, these gases are conducted through 
long flues or pipes and cooling-shafts, and on entering the foot of the con- 
densers the heat is reduced to about 140° Fahr., at which point the gases 
easily condense, and a strong acid is obtained at the same time. <A rather 
different method has been pursued for some time at Messrs. C. Allhusen and 
Sons’ works. Instead of the heat from the fire being conducted directly on 
to the drying materials in the furnace, a “close” furnace is used, in which 
the flame from the fire passes over a brick arch and under the bed of the 
furnace, and not in immediate contact with the materials; this furnace has 
no connexion with a chimney for its draught, and the gases from both the 
pan and dryer pass into one condenser. The hydrochloric acid passes off 
from the furnace unmixed with the smoke from the fire, and at a lower 
temperature than the ordinary method, and is consequently more easily con- 
densed, and obviates the necessity of long flues or cooling-shafts, Messrs. 
Allhusen and Sons have given us the following results of some recent experi- 
ments with this kind of furnace. The charge of salt generally used, was 
8 cwt., the moisture varied from 6 to 9 per cent., and the sulphate of soda 
contained from 1:75 to 2°25 per cent. of undecomposed salt. 
Theoretical 
Salt unde- Moisture weight Acid Loss per 
composed. per cent. of acid. obtained. cent. 
Ist experiment .... 1°75 7:0 502-0 495-06 1-4 
2nd FP we stenhs70 7:0 498-0 498-00 1:8 
3rd a eee i225 7:0 498-0 484-08 2°6 
4th 55 Sty 1480 7:0 498-0 490-04 1:6 
5th 3 are “L170 70 498-0 485-00 2°8 
Average.... 2-0 
As a further instance of the care that is now bestowed in condensing, we 
append also the result of some recent experiments conducted at the Walker 
Alkali Works to ascertain the actual quantity of muriatic acid condensed. 
The daily produce was conducted into large cisterns prepared for the purpose, 
and the strength, depth, &c., was carefully ascertained. The salt used was 
also tested daily for moisture and impurities, such as sulphates, sand, &c. 
The former was found to average 6 per cent., and the latter 1} per cent. 
during six months’ trial, thus leaving 92:5 per cent., NaCl=57-7 HCl in 
100 parts of salt used. 
The crude sulphate of soda produced was also daily tested for common 
salt left undecomposed, which is deducted below :— Test of 
HCl. Sulphate. 
January .... 100 parts of salt gave.... 58-3 25:9 
February.... i> 5 ja ce S30 2:24. 
March...... 4 4 fe eh 6402 2:25 
Aipral sare wisi. # i sive se anOei4 1:14 
May rata yes 3 ry wa. 584 2:98 
Junie sa See a 35 nls. 9 03'9)-- 2:12 
Anvetage TEG) 240%). . cee 55°8 2:45 
HCl left in sulphate of soda ...... 1:52 
57°32 
Logs per Cent oe ce tten cas 0:38 
57:70 
