8 Proceedings of the Royal Society of Victoria. 



Eissler's test is that it occupies some time and is not always 

 performed properly, while, further, it only applies to soluble 

 salts. 



For a practical test, I consider the magnet gives a better clue 

 to the state of the material in the furnace than any simple test 

 recommended, the temperature at the time being high enough to 

 decompose any ferrous sulphate. A sample can be readily taken 

 from the furnace with a semi-cylindrical iron tube, emptied on a 

 fire-clay tile, and the magnet run through it, when, if only a very 

 small quantity adheres, the ore is sufficiently roasted. 



Another test would be to make up a dilute solution of salt, 

 sulphuric acid, and a few crystals of permanganate of potash, 

 slightly stronger than that recommended by Professor Black. If 

 it is decolourised on adding the roasted ore to it, then this is not 

 sufficiently oxidised. 



When the ore is removed from the furnace, the chloridising 

 action of the salt, if added, still goes on, and the roasted material 

 remains red-hot under a thin black crust for some hours. If 

 this crust i.s broken, hydrochloric acid, volatile chlorides, and 

 free chlorine escape. Tests were made of a considerable quantity 

 of the ore, to determine whether any chloride of gold had 

 condensed on the crust ; but the results were negative. 

 Neither could silver chloride be detected ; but in the latter case 

 the amount present must have been very small and might have 

 escaped detection. 



The ore remained on the brick cooling floor until almost cold ; 

 it was then moistened with water in sufficient quantity to make 

 it adhere when pressed, but when released to fall to pieces. The 

 smaller the quantity used the better for successful working. 



The ore vats are lead-lined, with false bottoms and a gravel 

 filter-bed below ; both the filter-bed and the leaden sides are 

 pi'otected by wooden staves, which, together with all tlie internal 

 woodwork, have been dried, warmed, and dipped in a molten 

 paraffin bath. 



Tlie damped ore is fed into the vat through a sieve having 

 T) holes to the linear inch and is distril)uted evenly in layers with 

 a garden rake, no packing being done ; when full, the ore is 

 pressed tightly around the edge of the vat to prevent chlorine 

 escaping up the side, and the oi'e is raked away slightly from the 



