64 Mr Alger on New Loealities of Bare Minerals, 



is difficult to obtain the mineral entirely free. Its infusibility before 

 the blowpipe would seem to shew this. It has been suggested, also, 

 that a part of the iron may have been in the state of protoxide. It 

 seems impossible, without some such supposition, that substances so 

 closely resembling each other in all their physical characters, should 

 differ so much in chemical composition. Now, if the potash be left 

 out, and the peroxide of iron be changed into protoxide, the ratio 

 between the atoms of acid and bases is nearly the same as in Ottre- 

 lite, if we unite the atoms of magnesia and iron, as isomorphous with 

 each other. Ottrelite, also, is not easily separated from its matrix, 

 but the larger size of its plates would seem to render it more easy 

 to obtain pure specimens for analysis ; and it is to be observed that 

 Damour repeated his analysis, and obtained precisely the same result. 

 It is remarkable that Rammelsberg has alphabetically inserted Phyl- 

 lite, but has given no formula for its constitution. It seems proper 

 that the name of Phyllite, on the ground of its priority, and because 

 it expresses so well the ordinary appearance of the mineral, should 

 stand, and that of Ottrelite be abandoned. t 



Dysluite identical with Automalite. I am satisfied, from recent 

 observations, that these two minerals, as they occur in New Jersey, 

 should form but one species. The difference in hardness, colour, 

 specific gravity, and pyrognostic characters, can be accounted for by 

 the well established fact of the isomorphous replacement among the 

 constituents of certain minerals whitvh do not differ in crystalline 

 form. In Dysluite, we have but thirty per cent, of alumina, the 

 acting acid principle in the mineral, while, in Automalite, we have 

 sixty per cent. But the peroxide of iron, which is isomorphous with 

 the alumina, amounts to nearly forty-two per cent Now, if we 

 suppose about thirty per cent., of this peroxide of iron, to have re- 

 placed the same number of atoms of alumina in Automalite, and the 

 eight per cent, of protoxide of manganese to have replaced so much 

 of the oxide of zinc, we make up, very nearly, the essential consti- 

 tuents, as shewn in the analysis of Automalite by Ekeberg and Abich. 

 It is to be observed that the latter chemist puts down the iron as 

 protoxide in the Franklin Automalite. If it should prove that the 

 iron exists in Dysluite in both states of oxidation, the twelve per cent., 

 remaining out of the forty-two, may be protoxide, replacing so much 

 oxide of zinc. So that, in this view of the case, the 17 per cent, 

 oxide of zinc +11 per cent, protoxide of iron + 7 per cent, pro- 

 toxide of manganese = 35 per cent, oxide of zinc, which is nearly 

 the exact quantity found by Abich in the crystals from Franklin. 

 We may then state the constituents as follow : — 



f Brooke has supposed Phyllite to be identical with Gigantolite. If we com- 

 pare the analysis of Gigantolite with Daraour's analysis above, the evidence of 

 their identity (supposing Ottrelite to be a purer variety of Phyllite) is much 

 more marked, and the ratio between the atoms of acid and bases is nearly the 

 same in each. 



