..,..<:. ji^Q^n their Ores hy the Wet Way. S 



ter, and'el^fielled the excess of sulphur by a gentle heat. I 

 enclosed the residuum in about 100 grs. of assay lead, and 

 cupelled. The bead weighed 0'802 gr. This is a very much 

 smaller quantity than that previously obtained (exp. 3) by 

 treating the roasted ore in the state of coarse powder without 

 subsequent trituration, as was practised in the present experi- 

 ment. Is it probable that by the act of trituration the asso- 

 ciated matter present, which existed in so large a proportion 

 compared with that of silver, may have protected the silver 

 from the action of the hyposulphite? 



On adding sulphuretted hydrogen water to the filtrate, after 

 precipitation by sulphuric acid, not the slightest blackness was 

 produced. A precipitate of the pure colour of sulphur, canary- 

 yellow, was produced from the reaction of the sulphuretted 

 hydrogen upon the sulphurous acid remaining in the solution. 

 I transferred the ore, after treatment with the salt of soda, 

 into a glass jar, and passed through a stream of chlorine for 

 nearly an hour, stirred well, and left the jar with its contents 

 covered until the following morning. The odour of chlorine 

 still continued to be strongly evolved. I added chloride of 

 sodium, and digested for several hours on the sand-bath, re- 

 placingfrom time to time the water removed by evaporation: the 

 surface became covered with small white crystals. Afterwards 

 I added a solution containing 200 grs. of hyposulphite of soda, 

 and digested at a temperature just warm to the hand, stirring 

 well. I filtered and washed, and again treated the residual ore 

 with a further solution of hyposulphite containing 50 grs. of the 

 salt. I then filtered and washed. I mixed the two solutions, 

 and digested as usual with dilute SO^ in excess, and filtered. 

 On the addition of HS water to the filtrate, the latter became 

 dark-coloured. I then added an excess of HS water until 

 the odour of HS persisted, when after standing the filtrate 

 did not again become discoloured. I washed and dried. The 

 filtrate, which was readily detached from the filter without 

 sensible loss, was gently heated in a porcelain capsule to expel 

 the free sulphur. It then weighed 24 grs. I enclosed it, 

 together with the ash of the filter, which was incinerated in the 

 same capsule as used for expelling the free sulphur, in 200 grs, 

 of assay-lead. The capsule was not stained, and every appre- 

 ciable trace of matter was removed. By cupeliation I ob- 

 tained a bead weighing 5'005 grs. 



I again exposed the residual ore diffused through water to 

 the action of a stream of chlorine precisely as before, except 

 that after digestion during a few hours I added KO until an 

 alkaline reaction was obtained, the reaction having been found 

 to be acid. White matter, apparently similar to that pre- 



