April 10. 
Rev. B. LLOYD, D.D., Provost T. C. D., President, 
in the Chair. 
Rey. Charles William Wall, D. D., F..T.C.D., Robert 
William Smith, M..D., and William Armstrong, Esq., were 
elected Members of the Academy, 
A paper was read ‘On a new variety of Alumn,” by 
James Apjohn, M. D., M.R.I.A., Professor of Chemistry 
in the Royal College of Surgeons, Ireland. 
This paper commenced with a brief description of the 
physical characters and chemical properties of the mineral 
in question, which was found about 600 miles to the north 
of the Cape of Good Hope, near Algoa Bay, where it occurs 
in strata whose aggregate thickness is about twenty feet. 
The specimen described is composed of transparent threads 
or fibres, exhibiting a beautiful silky lustre, and in appear- 
ance closely resembling satin-spar or the finer forms of ami- 
anthus. In taste, solubility in water, and other properties, it 
corresponded with ordinary alumn. It was also easily shown 
to contain sulphuric acid and alumina, but in addition it 
contained a base which, though precipitated like alumina 
by potash, was not redissolved by an excess of the alkali. 
This, upon examination, turned out to be protoxide of man- 
ganese. There was no alkali, but about one per cent. of 
sulphate of magnesia. 
In the first attempt at effecting the analysis of the mine- 
ral it was found that alumen and protoxide of manganese 
could not be separated perfectly by potash, as some of the 
oxide was taken up by the alkali, while a considerable quan- 
tity of alumen was left behind with the oxide. The author 
explained a method of overcoming this difficulty, the parti- 
culars of which are given in detail in the paper. The fol- 
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