Gippsland Auriferous Ores. 9 



centre towards the circumference. If the false bottom is wet 

 before charging the ore, dry ore should be sieved in until no more 

 moisture is drawn up l)y capillary action. 



The chlorine first used was generated from sulphuric acid and 

 chloride of lime, but since it was impossible to get an even flow 

 of gas, we discarded these and used liquid chlorine, prepared in 

 Germany and exported in the usual steel cylinders, with 33^ lbs. 

 of chlorine in each. These work so well that, if the cost were 

 not so great (chlorine Is. 6d. per lb.) they would be largely used. 



The chlorine from the cylinders is turned on and passed 

 through a wash-bottle, so that the rate of flow can be regulated ; 

 from the wash-bottle it is conveyed to the centre of the false 

 bottom of the vat. 



The valve is turned so that chlorine can escape and pass 

 through a half-inch pipe against a head of one inch of water at 

 the rate of 6 bubbles per second. Yet at this speed it takes 6 

 hours to reach the surface of the ore. The cover is then lowered, 

 a water-joint at the circumference of the vat making a perfect 

 joint. 



The valve is now turned down, so that a bubble may pass 

 through the wash-bottle every 3 seconds, and this is continued 

 until there is no back pressure. Stress was laid by early writers 

 on chloi'ination about the necessity of separating hydrochloric 

 acid out with wash-water, and speculations were common as to its 

 injurious effects on the process. T. K. Rose^ has shown the 

 absurdity of the arguments brought forward. 



It was found that during the passage of the ore the pipes 

 became blocked up on cold nights, and, on investigation, the 

 solid substance proved to be chlorine hydrate. Tlie expansion of 

 the gas on being released was sufficient to cause the cylinders to 

 become frosted over in a few hours. It was also found that 

 watery vapour diff'used back into the chlorine, and this started to 

 corrode the valves. These difficulties were overcome I)y using 

 strong sulphuric acid in the wash-bottle. 



The ore is allowed to remain for 48 hours in contact with the 

 gas, and at the end of that time samples are taken from top to 

 bottom, and tlie gold chloride is washed out. From 2000 to 3000 



1 The Metall. of Gold, p. 253. 



