18 MANGANESE DEPOSITS OF INDIA : INTRODUCTION. [ PaRT I : 
classifying manganese oxide amongst the calxes rather than amongst 
the earths. At Bergmann's request, Scheele experimented on manga- 
nese, and, although he did not succeed in isolating the metal, he 
discovered sufficient of the characters of its compoimds to show the 
existence of a new element 1. Two years later (1776) Gahn succeeded 
in isolating the metal2. 
Of all the elements manganese is one of the most widely distributed 
throughout the three kingdoms of Nature ; it is 
Distribution in Xature. , , , , , . . , , . . . , 
to a large extent co-extensive with iron m its 
occurrence. 
The total number of well-defined minerals yet found in the earth's 
^ s ■ th crust, either in its rocks or its mineral deposits, 
mineral kingdom. is in round numbers about 1,000. Of these about 
130 to 140 contain manganese as an essential 
constituent, whilst many more often contain it in less important quan- 
tities. The consequence is that most of the rocks of the earth's crust 
contain manganese, though usually in small proportion only. According 
to F. W. ClarkS 0*10 per cent, of the earth's crust consists of manga- 
nese protoxide (MnO), manganese ranking as the fifteenth most import- 
ant element in this respect. As the result of the decomposition and 
denudation of the earth's surface by meteoric agencies, its various 
constituents are carried either in suspension or solution to the sea. 
It has been estimated by Murray* that one cubic mUe of average 
river water contains in solution 5,703 tons of manganese sesquioxide 
(Mn203), and that 6,524 cubic miles of river water are annually 
discharged into the sea5. This means that about 37,000,000 tons of 
Mno03, containing nearly 26,000,000 tons of metallic manganese, are 
brought every year by rivers into the oceans. This process has pre- 
tsnmably been going on for untold ages, so that now we should expect 
to find large quantities of manganese salts in solution in sea-water. 
This, however, is not the case, and it seems bo me that in this dis- 
appearance of manganese from solution in the water we have the 
1 Stockholm INIcmoirs, 1774 (Kongl. Svenska Vetenkaps-Akademiens Handlingar) 
! Penrose) ; also see ' The Chemical Essays of Charles William Scheele translated from 
the Transactions of the Academy of Sciences at Stockholm ' by Thomas Beddoes, 
London (1780), Essay V. 
2 Roscoe & Schorlemmer, Vol. II, Part II, p. 2. 
3 17. S. Gcol. Surv. Bulletin No. 228, p. 19, (1904). 
4 HcoUixh Geographical Magazine, III, p. 77, (1887). 
5 Op. cit_, IV, p. 41. 11888). 
