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nature, such as coarse sandstone, and pinkish white portions of a 
body resembling felspar. 
By a preliminary test, the powdered glassy matter was found to 
contain metallic iron, and where the vitrified material existed in 
sufficient quantity, the following points were ascertained : — 
1. The specific gravity. 
2. Action of alkalies and acids. 
3. Chemical composition. 
The specific gravity ascertained in the manner usually adopted in 
the laboratory was found to be 2*35. 
The method used for the analysis was the same that is generally 
employed for silicates, the iron, as peroxide, separated from the 
alumina by reduction in hydrogen, and subsequent separation by 
permanganate of potash ; the metallic iron was estimated by measur- 
ing the quantity of hydrogen evolved from a known weight of sub- 
stance. 
The alkalies present were estimated by fusion of the substance 
with baryta. 
The upper surface of Duno’deer was soluble in acids to the amount 
of 20*46 per cent., consisting of silica, peroxide iron, protoxide of 
iron, alumina, and lime. 
Alkalies acted upon it to a small extent, dissolving only 0*93 of 
a grain per cent., which was composed mainly of silica and alumina. 
The quantitative composition was found to be the following : — 
Silica, 
46-80 
Peroxide iron, 
19*92 
Alumina, . 
20*07 
Lime, 
7-81 
Magnesia, . 
0*89 
Iron, 
o-ii 
Potash, 
0*94 
Soda, 
3*44 
99*98 
Ratio of oxygen in the bases 
to that of silica as 1 : 1. 
Oxygen quotient, 0*7 6. 
The under surface of this specimen was not so uniform in appear- 
ance as the upper one, small crystals resembling felspar being 
scattered through it ; these crystals, however, were not included in 
the portion taken for analysis. As the vitrified surface was smaller 
in extent than that of the preceding specimen, the action of acids 
and alkalies had to be omitted. 
