350 . J. P. Cooke, Jr. on determining amount, etc. 
much as would be required in any mineral analysis. The re- 
sults were 
No. 1, 14 grams iron salt required 26°35 ¢, m.° permanganate. 
No “ “ “ “ “ 26°3 5 “ “ 
inte 
No. 3, “c +“ “ “ “ 96°4 “ “ 
No. 4, t3 6 “ “c “ 26°45 ‘cc “ 
From a specimen of very dark green actinolite treated as 
above 
described we obtained in three determinations the follow: 
Ing results. 
No. 1, 0°6913 grams of mineral required 14°1 ¢, m.* permanganate. 
No. 2, 0°6640 « bd “ *“ 13°6 “ “ 
No. 3, OS01O eit « “ ti 18°2 “ “ 
The per centage composition deduced from this is 
Per cent of FeO. 
No. 1, 19°86, 
No. 2, 19°95 
No. 3, 19°89 
In order to test still further the efficiency of our apparatus we 
have several times dissolved 2 decigrams of iron in dilute sul- 
phuric acid and heated the solution in the bath for more than 
twelve hours without its undergoing the slightest oxydation. — 
It is of course essential in this process that both the sulphurie 
and hydrofluoric acids should be perfectly pure and wholly free 
from any oxydizing or reducing agents. There is no difficulty 
in obtaining from the manufacturers pure sulphuric acid, but un- 
it apt to be very 
where 
: exposed to the ant 
Of course in such cases a glass beaker would take the goon! 
the platinum crucible, as is shown in the figure. Lastly, 
method of heating in an atmosphere of steam will be found very 
convenient in the many cases where it it is desirable to preve® 
the evaporation of water during the process. The annie 
the steam moreover, prevents to a great degree the escape of t . 
volatile acids; so that in the process above described, the glass 
covering tunnel is not perceptibly corroded unless the hydro 
used is very strong. i 
