304 MANGANESE. 



be distinguished by the property of imparting a purple or violet 

 colour to borax. 



Sp. I. Grey Manganese, or Oxide of Manganese. Pl. 

 XLIII. fig. 1. — Graun braunstcinerz, Werner; Manganese oxide 

 metalloide, Huutj. — It is of a dark steel-grey colour, inclining more 

 or less to iron-black. It occurs in a great variety of forms, either 

 regularly crystalized, or acicular, also massive, dendritical, and in 

 fibrous and radiated concretions. The lustre is shining or glimmer- 

 ing, and metallic; the fracture conchoidal and earthy. The mas- 

 sive varieties have either a granular, a laminar, or a fibrous struc- 

 ture, or they arc compact, and their texture earthy and dull. It is 

 soft, brittle, (except the compact variety,) and soils strongly when 

 rubbed, giving a black streak. It is infusible before the blow-pipe, 

 and tinges borax purple. The specific gravity varies from 3*5 to 4*7. 

 One hundred parts of the crystalized variety yielded, oxide of 

 manganese 90 - 5, oxygen 2'25, water 7 ; the compact afforded, 

 oxide of manganese 60, silex 25, water 13. — Klaprolh. This ore 

 is found in most of the countries of Europe, frequently in iron 

 mines. It occurs in veins and imbedded masses, both in primi- 

 tive and secondary rocks, near Upton Pyne, in Devonshire, in 

 various places in Cornwall, and near Aberdeen, in Scotland. In 

 Ireland it occurs with brown iron ore, at Howth, near Dublin. 



Grey manganese ore is used in large quantities in the prepa- 

 ration of chlorine in the manufactory of chloride of lime (common 

 bleaching powder) ; it is also used by glass-makers to destroy the 

 brown tint which that material receives from the admixture of 

 inflammable substances. It is admitted into the list of materia 

 medica, as the cheapest and most convenient substance from which 

 to procure oxygen gas. For this purpose a quantity of the ore 

 reduced to a coarse powder, is exposed to a red heat in an iron 

 retort, the beak of which is introduced under a large jar filled with 

 water, inverted and placed on the shelf of the pneumatic trough. 

 It may also be obtained by exposing the ore to a gentle heat in a 

 glass retort, with half its weight of strong sulphuric acid. Oxygen 

 gas, when respired, acts as a stimulant ; it increases the force and 

 velocity of the pulse, and has been employed as a remedy in 

 asphyxia, chlorosis, asthma, dropsies, paralysis, and some other 



