president's address SECTION B. 67 



sided inferences similar to those which existed for astronomy 

 and mechanics in the days of Newton." It is well to remem- 

 ber that Newton devoted much time to chemical experiments, 

 and while considering questions of celestial mechanics, per- 

 sistently kept in view the mutual action of those infinitely 

 small worlds which are concerned in chemical evolutions. 

 For this reason, and also to maintain the unity of laws, it 

 seems to me that we must, in the first instance, seek to 

 harmonize the various phases of contemporary chemical 

 theories with the immortal principles of the Newtonian 

 natural philosophy, and so hasten the advent of true chemical 

 mechanics. 



As the avowed object of most of the addresses that are 

 inflicted upon us should be " to point a moral : to adorn a 

 tale," we ask ourselves. Is there no interest in this question of 

 salt-solution for us here in Australia ^ I venture to believe 

 there is. And thus we come back to the question of the 

 action of solvents generally, and the practical application 

 of them in what are called wet processes in mining and 

 metallurgy. 



The extraction of metals from their ores has been effected 

 from time immemorial by the old well-known methods of 

 smelting, the object generally aimed at being the separation 

 of the metal in the molten state by the addition to the ore of 

 some mineral or earthy substance to cause the mixture to fuse, 

 flow, or flux while subjected to the great heat of a furnace, 

 the metal separating out by itself in a more or less pure 

 condition. 



The cost of such a scheme of well-planned operations as 

 these will, of course, vary with the degree of richness of the 

 ores, the cost increasing with the poverty of the ore treated, 

 a limit soon being reached which depends on local and other 

 conditions, and the poor oi'es can only be regarded as so 

 much useless rubbish that will not pay for smelting. In such 

 cases a wet process for extracting the metals might be advan- 

 tageously employed, and we may dissolve the precious metals 

 in a watery solution and collect them by suitable -means. To 

 the miner who is unfamiliar with such a process it sounds an 

 impossible and an uncanny way of doing things. However, 

 several wet methods commend themselves to the metallurgist 

 in cases where the ores are too poor to be worked economi- 

 cally by any other means. 



Speaking generally, the end in view is to obtain the metals 

 in a soluble form, either as chloride, sulphate, or cyanide, and 



