1889. 1 on Aluminium, 455 



ones substituted. Those removed eacli contain on an average about 

 6 lbs. of metal, and are taken directly to the sodium casting shop, 

 where it is melted and cast, either into large bars ready to be used for 

 making aluminium, or in smaller sticks to be sold. 



Special care is taken to keep the temperature of the furnaces at 

 about 1000^ C, and the gas and air valves are carefully regulated, so 

 as to maintain as even a temperature as j^ossible. The covers remain 

 in the furnace from Sunday night to Saturday afternoon, and the 

 crucibles are kept in use until they are worn out, when new ones 

 are substituted without interrupting the general running of the furnace. 

 A furnace in operation requires 250 lbs. of caustic soda every 

 one hour and ten minutes, and yields in the same time 30 lbs. of 

 sodium, and about 240 lbs. of crude carbonate of soda. With the 

 four furnaces at work 120 lbs. of sodium can be made every 70 minutes, 

 or over a ton in the 24 hours. The residual carbonate, on treatment 

 with lime in the usual manner, yields two-thirds of the original 

 amount of caustic operated upon. The sodium, after being cast, is 

 saturated with kerosene oil, and stored in large tanks holding several 

 tons, placed in rooms specially designed both for security against either 

 fire or water. 



Chlorine Manufacture. 



This part of the works is connected with the adjacent ^vorks of 

 Messrs. Chance Bros, by a large gutta-percha pipe, by means of 

 which from time to time hydrochloric acid is supplied direct into 

 the large storage cisterns, from which it is used as desired for 

 making the chlorine. For the preparation of the chlorine gas 

 needed in making the chloride, the usual method is employed ; that 

 is, hydrochloric acid and manganese dioxide are heated together, 

 when chlorine gas is evolved with effervescence, and is led away by 

 earthenware and lead pipes to large lead-lined gasometers, where 

 it is stored. 



The materials for the generation of the chlorine are brought 

 together in large tanks, or stills, built up out of great sandstone slabs, 

 having rubber joints, and the heating is effected by the injection of 

 steam. The evolution of gas, at first rapid, becomes gradually slower, 

 and at last stops ; the hydrochloric acid and manganese dioxide being 

 converted into chlorine and manganous chloride. This last com- 

 pound remains dissolved in the " spent still liquor " and is recon- 

 verted into manganese dioxide, to be used over again, by Weldon's 

 Manganese Eecovery Process, Owing to the difficulty of keeping up 

 a regular supply of chlorine under a constant pressure directly from 

 the stills, in order that the quantity passed into the sixty different 

 retorts in which the double-chloride is made can be regulated and 

 fed as desired, four large gasometers were erected. Each of these is 

 capable of holding 1,000 cubic feet of gas, and is completely lined 

 with lead, as are all the connecting mains, &c., this being the only 

 available metal which withstands the corrosive action of clilorine. The 



