i899 THE PRESIDENT'S ADDRESS 23 



gravel beds ; and so economical is the process that a 

 yield of a very few grains of gold to the ton will pay ; for 

 the cost of moving a ton of ordinary material rarely 

 exceeds 2d or 3d. It is marvellous to see how the force 

 of the water will cut right into a hill side and bring great 

 boulders of rock rolling down into the stream. I once 

 saw a railway cutting being made by hydraulicking, and 

 the process seemed to answer most admirably. 



How the gold has got into the bed of these streams is a 

 very interesting subject for investigation. 



Of course it has all come out of veins, or " ledges " as 

 they are usually called in California, which during count- 

 less ages have been gradually washed away with the rocks 

 that enclosed them. There are two distinct theories on 

 the subject : — One, that the gold has been dissolved out 

 of the ledges, carried down to the canons in solution, and 

 there again deposited in the stream as fragments of gold ; 

 the other, that the process has been purely mechanical, 

 that bit by bit the " ledges " have been washed away, 

 pounded up by the action of torrents, the particles of 

 gold have been separated out, and have gradually gravitated 

 on to the bed-rock in the streams. 



The facts urged in support of the precipitation theory 

 are as follows : — 



1. The raritv of nuggets or gold masses of any con- 

 sideral)le size in quartz veins. 



2. The greater purity of the gold contained in placers 

 than that in the neighbouring ledges or veins. 



3. The frosted character of the surface of some gold 

 nuggets. 



4. Instances of deposition of gold in organic sub- 

 stances buried in the gold [dacers. 



5. The solul)ility of gold as proved by laboratory 

 experiments. 



