YORKSHIRE AlUM WORKS. 253 



and then reducing it again to 1-35: this method obliges 

 them to evaporate a very unnecessary quantity of water. 



The alum liquor is frequently brought into the pans as 

 lowasl'09; when by repeatedly bringing the liquor over 

 fresh calcined mine, it might be concentrated to 1*25, or 

 more. I will mention an instance where the expenditure in 

 evaporating liquor was more than £3 lOs. daily; when at 

 the same time tliis liquor might have been concentrated to 

 an equal degree, by repeatedly pumping the liquor upoR 

 fresh calcined mine, at an expense of not more than Qs, 

 in the same time; here there was a loss of £3 Is. daily. 



In using black ashes, or kelp, a considerable quantity of \ 

 charcoal is dissolved in the alkaline lee; this charcoal is pre- 

 cipitated on adding a small quantity of the solution of sul- 

 phate of alumine, bat is redissolved again by adding the 

 solution in excess. 



This charcoal then contaminates the alum, and deccin- 

 poses a quantity of the sulphuric acid: therefore, it must 

 appear conclusive, that whatever alum is made with muriate 

 of potash alone will be far superior in quality, while the 

 produce will be greater in quantity. 



It might be supposed, that urine was a necessary ingre- 

 dient in the making of alum ; but the fact is, it merely 

 hides the ignorance of an alum maker. Having no deter- 

 minate rule to guide him, in reducing the liquor from thje 

 pans, should he chance to exceed the specific gravity of 

 1*35, he adds urine, or some such light fluid, to bring the 

 liquor as near as possible to this density. The alum works, 

 that approach the nearest to the true chemical principles, 

 are those of the Right Hon. Lord Dundas, and Messrs. 

 Baker and Co. They use no urine in these works — the 

 alum liquor is always clarified previous to its being used — 

 they use no alkali generally, but crystallized muriate of 

 potash — greater economy is observed in the consumption of 

 fuel; and the result is a product of alum considerably 

 larger in a given time, and of better quality, than can be 

 produced by the works established upon the old plan. 



The kelp used is obtained by burning the sea wrack in Remarks on 

 kilns, at a great number of places upon the coast of Eng- p^^y^J^ -'^V"' 

 laud, Scotland, &g. It is a very inferior alkali in an alum maiiufaciure. 



manufactory. 



