196 ON THE DECOMPOSING POWER OF HOT STEAM. 
of the patentee, have been more successful than his smaller 
trials, which leads to the inference of yet happier results 
arising out of improvements in the steam heating apparatus. 
They have also shown that the consumption of fuel, and 
cost of labour per ton of soda, will be less than one half of 
the old method. At the high price of the pure alumina used 
for their experiments, they can make soda much cheaper 
than by the old process, and as they have been able to ex- 
tract that earth at one-sixth of the present manufacturer's 
price, the profits must be very considerable, viewed in 
reference to the immense extent of the manufacture. 
Under date of May 18th, 1S4S, from Glasgow, we are 
informed that Mr. Tennant, of the St. Rollex' works, has 
completed a furnace on Mr. Tighlman's plan, and it was 
expected to be in operation within a short time. 
When we consider, that according to Muspratt, of Liver- 
pool, there are seventy thousand tons of soda ash made in 
Great Britain annually, valued at forty-five dollars per ton 
— three million one hundred and fifty thousand dollars — and 
that probably the rest of Europe makes as much more, we 
cannot but be struck with the immense importance of the 
new process. 
But this is only one of a number of applications of the 
law of decomposition by steam. Vast deposits of sulphates 
exist, as gypsum and baryta, which by this process are 
available as sources of sulphuric acid on the one hand, and 
lime or baryta on the other. 
This last earth will doubtless, if rendered a cheap ma- 
terial, be found to possess many valuable properties in the 
arts as a cement, &c., hitherto but little developed. 
Magnesia, so largely consumed as a medicine, is at once 
obtained from the sulphate, without the long process of 
washing and drying the carbonate and subsequent calcina- 
tion, and when attention is properly turned to this branch 
of manufacture, the pure sulphate may be at once converted 
into a superior medicinal magnesia. 
