ClIAP. XXVII.] MEtHODS USED ABROAD. 
^75 
' The installation has been carefully designed, and will have a capacity of 100 
tons of briquettes per day. The process has been evolved by Messrs.' Zeitz & Co. 
of Saxony who are supplying the greater part of the machinery. The binding 
material will be furnished by a proportion of the moisture left in the ore after re- 
ducing to the size of 1| millimetres. The presses will work with a pressure 
of 10 tons per square inch and the briquettes will weigh 800 grammes each. 
' Experimental briquettes have been found to resist shock and high tempera- 
ture without disintegrating, so much is expected from the process.' 
The Brazilian ores are very high in moisture (up to 20%) ; in bri- 
quetting soft Indian ores it might be necessary to add moisture. 
Further in an article in the Engineering and Mining Journal, 9th 
March 1907, p. 478, Mr. E. K. Judd gives an interesting account 
Hydrai.licking and wash, of the way in which the manganese-ore deposit 
ing at Crimora in Vir- at Crimora in Virginia is worked by the Crimora 
o^^^- Manganese Company, by hydra ulicking and 
washing. In order to show with what elaborateness a manganese-ore 
deposit may be worked I quote extensively from this article : — 
' The Potsdam quartzite, forming the base of the district, has been eroded by 
some peculiar agency so as to form a bowl, perfectly inclosed on all sides, except, 
where, at the north, a stream has eroded a narrow gorge. This drains only a small 
part of the bowl, and the remainder has no natural drainage whatever. The 
bottom of this bowl has been filled to a depth of 212 ft., at the centre, with a stiff red 
clay, covered with a layer of gravel drift with an average depth of 15 ft. In this 
clay, manganese oxides are found in rounded concretions, and irregular pockets, 
seams and stringers, whose position follows absolutely no apparent rule. They are 
found at ail depths, and in all shapes and sizes, from that of a pea to masses of 
several tons weight 
' The manganese-bearing portion of the bowl has been determined, by drill 
borings, to cover an area of a little over 100 acres. 
Method of Mining. 
' In the early days, when the ores first attracted the attention of the Carnegie 
steel interests, the clay was thoroughly honeycombed with shafts and drifts which 
required timbering of the most substantial nature. The lowest workings of that 
epoch reached a depth of about 100 ft. below the original .surface, when the copious 
infl ux of water naturally gravitating to this .spot and finding no outlet, forced aban- 
donment of the project. Although the old operators removed the choicest ore- 
bodies, the inefficiency of their methods is showi by the great quantity of valuable 
ore that is now recovered, by ojjen working, from the close neighbourhood of the 
old openings, and even in among the very timbers of the disused drifts. 
' The present system of mining may have been suggested by that so successfully 
practised among the largest gold gravel operators of the Sierras, hut it is probably 
unique among manganese miners. The first step was to drive a drainage tunnel 
5,800 ft. long through the quartzite run, tapping the bottom of the basin at its 
lowest point, and discharging into one of the small streams that flow into the south 
fork of the Shenandoah. A shaft 202 ft. deep then connected its inner end with 
