Hardman — On the Substitution of Zinc for Magnesium. 147 



one, for with care the metal is easily reducible, With less than half 

 a grain of mineral, containing a mere trace of zinc, fused on one of 

 Griffin's reduction pastiles, I have obtained sufficient of the metal to 

 apply the most characteristic wet tests, and such as could leave no 

 doubt as to the nature of it ; while with large capsules, and a properly 

 managed reducing flame, the feat is perfectly easy with larger quan- 

 tities. 



The following list gives the principal specimens in which I have 

 found zinc : — 



(1). Talc Schist from the sea shore, Mullaghglass, county Galway,'^ 

 containing large, well-defined hornblende crystals. The blowpipe 

 analysis gave strong indications of zinc. This was confirmed by a wet 

 analysis, which showed the presence of zinc in appreciable quantity. 

 Small quantities of copper, silver, lead, and nickel were also present. 



(2). Hornblende. — The crystals from the above also contained 

 zinc. 



(3). JDarh-green Serpentine from JS". slope of Croagh Patrick Moun- 

 tain, county Mayo, contains considerable traces of zinc ; also copper, 

 and a small quantity of nickel, quite enough for estimation. This 

 fact deserves particular notice, since it is the only serpentine in this 

 country, as far as I am aware, in which nickel has yet been observed. 

 Doubtless it is of not unfrequent occurrence in such rocks, but Dana's 

 lists of analysis only mention a few localities, most of which are Ameri- 

 can.^ It might be expected also to occur in magnesian rocks, its com- 

 pounds being isomorphous with the corresponding ones of magnesium 

 and zinc ; and, in fact, I have often met with it in such rocks, but 

 never in such large quantity as in this specimen. 



(4). Flesh-coloured Dolomite from the carboniferous limestone of 

 Ballyfoyle, near Kilkenny. The blowpipe showed zinc to be present, 

 which was confirmed fully by a wet analysis. Small quantities of 

 copper and lead were also present. 



(5). Dolomite from Ballyfoyle, similar to above. Presence of zinc 

 shown by blowpipe and wet analysis. In both these in small quan- 

 tity for magnesian rocks. 



(6). Dolomite from- Clara, near Kilkenny, similar to the above ; 

 extremely friable, contains crystals of calcspar; blowpipe examina- 

 tion proved the presence of both zinc and lead. Two wet analyses 

 confirmed this, and showed the zinc to exist in estimatable quantity. 



2 For tliis and other Galway and Mayo specimens I am indetted to my col- 

 league Mr. G. H. Kinahan, M. R. I. A. For several others, to my colleagues 

 Mr. Nolan, M. R. I. A., and Mr. Henry. 



^ Since ■srriting this I find it has heen noticed in the black serpentine of the 

 Lizard. See Rev. T. G. Bonney, M. A., and W. H. Hudleston, Esq., M. A., 

 " On the Serpentine and Associated Rocks of the Lizard District," Journal Geo- 

 logical Society of London, 1877, p. 925. Mr. Kinahan informs me that nickeUferous 

 pyrrhotite occurs in veins in the old beds of the Croagh Patrick distiict. The age 

 of their veins is, however, not cartain. 



