302 PROCEEDINGS OF SECTION B. 
this low-grade stuff cost nothing delivered on the surface. Its 
value ran from 7 to 12 per cent. lead and from 6 to 14 oz. of 
silver; and the question was: Could this low-grade material be 
concentrated at a profit? Without further treatment the ore was 
worthless ; but the carbonate concentrate that was produced from 
the ore was infinitely preferable to use in the furnaces than the 
crude sulphide ores. Looked at in these days, when carbonate 
ore high in lead is getting to be worth more than the value of its 
metallic contents, there would be no hesitation as to what would 
be done with the low-grade ore ; but in those days, when lead ore 
in the carbonate form was plentiful, when the value of a ton of 
lead in Broken Hill was but 50 per cent. of its London market 
price, the wisdom of some of the immense concentration plants 
which were erected seems doubtful. Block 14, the British Com- 
pany, and the Proprietary, rushed into enormous expenditure ; 
whereas one only of the first concentration plants erected would 
have demonstrated for evermore their uselessness on the = of 
ore that had to be treated. 
The first system of concentration was with the Collom jig, and 
after, treatment to recover the rich slimes by a kind of Linkenbach 
table. The ore was first crushed with an enormous steam-eating 
stamp—the very worst system of crushing which could have been 
devised for this class of ore. Think, fora moment, of the compo- 
sition of the ore—a hard quartz and a friable carbonate of lead. 
Every blow of the stamp shattered the quartz into fragments— 
of that there could be no doubt; but it smashed the bulk of the 
carbonate of lead into slimes. The stamp was something like the 
whole plant —there was no economy in the structure of either, and 
when finished neither did the work expected of them. Both the 
stamp aad the jig were splendid appliances for dealing with ore 
like they have at Lake Superior, U.S.A., from whence they were 
imported, where the ores were copper, the latter existing almost, 
if not altogether, in the metallic form. No smashing blows could 
do any mischief on this class of material, and the large crushing 
capacity of the steam stamp was thus an advantage. 
Time went on, and the steam stamp was thrown out on the 
scrap heap, and a good many of the Collom jigs also. Alterations 
were made in their motions, notably at the British Mine, where 
the tappet motion of the plunger was altered and driven with 
an eccentric, so giving a more even pulsation in the jig. This 
improvement was a good one; and if the size of the jigs had been 
about three times greater, considerably better recovery would have 
been made ; for, after all, the Collom jig, as used in Broken Hill, 
was but a toy. As the carbonate ores began to disappear, the 
attention of the mine managers was impelled to the sulphide 
problem, of which volumes have been, and no doubt will yet be, 
written. 
