524 
MAXGA>-ESE DEPOSITS OF INDIA : ECONOMICS. [PaRT III r 
of mixed psilomelane and braunite from Kodegaon, and 0-50% in a 
specimen of braunite with psilomelane from Kandri. The ai^erage of 
these 21 is 0-175% K2O. The average of the whole 46 analyses is 0-71% 
K2O. The results obtained by the two sets of analysts seem at first sight 
to be very discrepant. But it must be remembered that the specimens 
analysed by the Imperal Institute did not include any specimens of 
psilomelane unmixed with braunite ; whilst amongst the specimens 
analysed by .J. and H. S. Pattinson there were several pieces of pure 
psilomelane, vrhich is the manganese-ore that contains the largest quanti- 
ties of alkalies. The potash and soda in this mineral probably occur as 
K^MnOg and Na^MnOg, respectively. 
In the case of the soda, which is present in much smaller amount 
than the potash, the two sets of analyses agree 
. 0 a in ma h ^^^^ ^^^jj analyses by the Imperial Institute 
show soda present in every case, the smallest amount being 0-13%, and 
the largest O-oO^q, this latter being found in a specimen of braunite 
mixed with a certain proportion of psilomelane, from Kandri. The 25 
analyses by J. and H. 8. Pattinson show from as little as 0 -02% Na20 in a 
specimen of the lead-like psilomelane of Avagudem, to 0-57% in the 
hoUandite of Balaghat. The average amount in the total of 46 analyses 
is 0-24%, which is one-third of the average amount of K2O. 
An unexpected constituent of the Indian manganese-ores is arsenic. 
The finding of three different species of arsenates 
Arsenic in manganese- ores. ■ j. j ' -.i .r r t 
associated with the Indian manganese-ore 
deposits is noticed on page 218 in the section of mineralogy. It was the 
detection of the Sitapar arsenate that led to the testing of the Indian 
ores generally for this constituent. A sample of the Sitapar ore was 
cleaned into two samples, one free from visible arsenate — which is practi- 
cally white and hence easily separated — and the other containing all the 
visible arsenate. The amounts of arsenic oxide, AS2O5, were found to 
be 0-003% and 0-095% in the two cases. Fifty- nine samples and 
specimens of Indian manganese-ores were tested for this constituent. Of 
these, all tested by the Imperial Institute have been found to contain 
arsenic, whilst of those tested by Messrs. J. and H. S. Pattinson, have 
been found to be free from arsenic, and 24 to contain it. The maximum 
was 0- 30.5% As20g found in a sample of mixed psilomelane, braunite, 
and pyrolusite, from ICajlidongri, one of the arsenate localities. Other 
results of 0-050 or over are : 0-214%, 0-05.5%, and 0-0.50%, in other 
samples from Kajlidnngri, 0-006% in a sample of mixed psilomelane, 
