80 ANNUAL OF SCIENTIFIC DISCOVERT. 



facilities for exactness. The details obtained in these experi- 

 ments, as to the degree of coninnniition readied by this apparatus, 

 have been very carefully worked out, but are reserved for a 

 future eoninninifaliun, having no bearing on the subject now 

 before us, although Ixdieved to be of value to the art of ore- 

 dressing. After detailing the several experiments which were 

 actually concludi'd, rrolt'ssor Sillinian observes, that the exper- 

 iments are still in progress, but the results show that, with un- 

 aided mercury, the gold saved is less than sixty per cent, of the 

 whole quantity of gold known to be present, in one experiment 

 less than forty per cent, was saved, while, by the aid of the amal- 

 gam of sodium the saving is increased to eighty per cent., or an 

 increase of more than twenty per cent., leading to the reasonable 

 expectation that, in the large way, at least eighty per cent, of the 

 gold present in a given case may be saved, and, in many cases, 

 where the golil is coarse and Iree, that even better results than 

 this may be attained. The fu-st experiment detailed, in which a 

 different amalgamating apparatus was used, gave results surpris- 

 ingly close. He does not tiiink the Ixirrel as good a form of ap- 

 l)aratus for this description of amalgamation as some one of the 

 numerous forms oi pan now in use. It was emplo3ed in these 

 experiments simplj' because it was a convenient means of treat- 

 ing small (iuantiti(!S of ore in making comparative experiments. 

 Experiments in California, muler his direction, have ijeeu set on 

 foot upon a scale of magnitude adequate to test the value of this 

 discoveiy, in the metallurgy of gold, in a satisfactory manner, the 

 results of which may now be looked for at no distant day. With 

 regard to the mode in which the sodium acts. Professor Silliman 

 remarks that the action of the sodium in this case ajipears to be 

 in a manner electrical, by placing the mercury in a highly elec- 

 tro-positive condition towards the electro-negative gold, seeming 

 to give some reason for the term magnetic amalgam, ado2)tcd by 

 INIr. Wurtz, as the trade-mark of the alloy. The quantity of 

 sodium is entirely too small to allow of the supposition that it 

 acts by its chemical affinities. It is well known to chemists that 

 the metallic sulphides are decomposed by amalgam of sodium ; 

 but no one supposes that an inventor could be found so Quixotic 

 in his chemical notions as to seriously propose the use of sodium 

 amalgam as a means of eftecting the reduction of the sulphides 

 af silver, etc., since not less than one equivalent of sodium would 

 be required to set at liberty one equivalent of silver. The use of 

 the sodium amalgam for silver amalgamation must depend, if 

 found really useful in the large way in the silver reduction 

 process (which still remains to be proven) , upon a like power of 

 electrical action to that seen in its action on gold, and also on the 

 well-known power of preventing the granulation (flouring) of 

 mercury, or on saving the mercury Avhen thus changed. Indeed, 

 there is good i-eason for believing that a most important part is 

 played by the sodium amalgam in this last particular. The amal- 

 gam of gold or silver is very liable, as eveiy mill-man knows to 

 his loss, to granulate and disappear from the plates of the battery, 

 or from the riffles, after it has been formed. If this granulation 



