58 
found that the influence of the raj^s of the sun focussed by 
a concave mirror 2 feet in diameter, caused a revolution of 
1 millionth of an inch in a second. 
‘^The instrument was protected by some sort of glass 
shade. 
The same motion was produced in a vacuum.” 
^'Note on a Manganese Ore from New South Wales, and 
on a Specimen of Native Silver from New Zealand,” by 
M. M. Pattison Muir, F.RS.E. 
I lately received a small specimen of manganese ore taken 
from a very large deposit near Bathurst, N.S.W. The ore 
is said to constitute the greater part of a considerable moun- 
tain in that neighbourhood. 
The sample was greyish-black in colour; when broken it 
exhibited an ill -defined crystalline structui’e, and showed 
patches of dark brown or black intermingled with others of 
dark steel-grey colour. 
When heated in a small glass tube a considerable quan- 
tity of water was evolved. 
The amount of manganese dioxide was determined by 
the oxalic acid method of Fresenius and Will : the total 
quantity of manganese was also determined by precipitation 
vdth bromine water, after removal of ferric and aluminic 
oxides : the excess of manganese above that reqj^uired for 
the formation of the amount of dioxide found to be present 
was calculated to protoxide. 
The following are the results of the analysis. 
Manganese Dioxide 78 ’72 per cent. 
„ Protoxide 
, 3-66 
Ferric and Aluminic Oxides . . . 
, 6-50 
JJ 
Silica 
5’80 
JJ 
Moisture 
4-75 
99'43 
