16 



AMALGAMATION. 



tious and experienced metallurgists of California, at 

 one time connected with the Geological Commission 

 of that State, informed me that by his own determina- 

 tions the saving in a large number of cases was barely 

 30 per cent, of the gross contents of the ore, as shown 

 by careful assays, both of the ore and the waste. 



The causes of this large loss are various, among 

 which may be mentioned imperfect processes, in- 

 sufficient comminution of the ore, and the diffi- 

 culty of bringing the gold into contact with the 

 mercury. In an ore containing one ounce of gold to 

 the ton of quartz or waste, the ratio is as one to 

 thirty-two thousand (1 to 32,000), or less than one- 

 fourth of one grain in one pound of stuff. 

 ' It is, however, well known to all who are conversant 

 with gold amalgamation, that the mercury often ap- 



Eears perfectly indifferent to the gold even when 

 rought in contact with it, failing to amalgamate it. 

 This indifference may be sometimes traced to a min- 

 ute portion of grease, which effectually checks amal- 

 gamation, but it is quite as often due to some other and 

 less obvious cause, baffling often the skill of the best 

 amalgamators, and resulting in a ruinous loss of the 

 precious metal. 



Numerous inventions have been devised to save 

 this loss, and avoid the causes which involve it, but 

 until lately with very indifferent success. One of the 

 most promising, viz., the use of mercurial vapor, has 

 proved itself on trial in the large way a failure, 

 and the problem has remained, in a great measure, 

 unsolved. 



Early in 1864 Prof. Henry Wurtz communicated 

 to me in conversation his conviction, as the result of 

 preliminary experiments, that the use of a minute 

 portion of the metal sodium would impart to mercury 

 the power of amalgamating with gold readily under 

 any of the adverse conditions wnich had thus far 

 proved a serious drawback to the practice of this art. 

 Leaving soon afterward for California, I have had no 

 opportunity, until within a few months past, of ac- 

 quainting myself with Mr. Wurtz's plans. 



Prof. Silliman also explained some experi- 

 ments made to illustrate the remarkable prop- 

 erties imparted to mercury by sodium, and dis- 

 covered by Prof. "Wurtz. He says : 



1. Shake up in a test-tube a small quantity of mer- 

 cury (say half an ounce) with a moderately strong 

 solution of sulphate of iron. The mercnry is pres- 

 ently reduced to the condition of a thick mud, being 

 so completely granulated (floured) as to resist all ef- 

 forts to restore it to its proper condition, and retain- 

 ing this condition almost indefinitely. Drop now a 

 minute particle of sodium amalgam into it, when in- 

 stantly the whole is restored to its fluid state, and 

 subsequent efforts to reproduce the granular condi- 

 tion are futile if the least trace of sodium remains. 



2. Bring a particle of placer gold or gold from 

 quartz into contact with a little clean mercury in its 

 ordinary condition. It will be seen to push the gold 

 before it as it rolls about, and refuse to amalgamate 

 with the gold, even when beneath its surface. In 

 fact, there appears to be a sort of active repulsion be- 

 tween the two metals. 



3. Bring the same particle of gold in contact with 

 mercury having a minute portion of the sodium amal- 

 gam dissolved in it, when immediately the gold is 

 completely enfilmed by the mercury and disappears 

 under its surface. 



The description of the discovery, as given by 

 the inventor, shows, that it consists in impart- 

 ing to quicksilver greatly enhanced adhesion, 

 attraction, or affinity for other metals and for 

 its own substance, by adding to it a minute 

 quantity of one of the highly electro-positive 

 metals, such as sodium, potassium, etc. A 

 minute quantity of these metals, dissolved in 



quicksilver, communicates to it a greatly en- 

 hanced power of adhering to metals, and par- 

 ticularly to those which, like gold and silver, 

 lie toward the negative end of the electro- 

 chemical scale. This power of adhesion, in the 

 case of these two metals, is so great, that the 

 resistance, which I have found their surfaces, 

 when in the native state, usually oppose to 

 amalgamation (a resistance which is much, 

 greater and more general than has hitherto 

 been recognized, and which is due to causes as 

 yet undiscovered, or at least uninvestigated), is 

 instantly overcome, whether their particles bo 

 coarse, fine, or even impalpable. Even an ar- 

 tificial coating of oil or grease (which is such 

 an enemy to amalgamation that the smoke of 

 the miner's lamp is pronounced highly detri- 

 mental in gold and silver mines) forms no 

 obstacle to immediate amalgamation by this 

 magnetic quicksilver. The atoms of the mer- 

 cury are, as it would seem, put into a polaric 

 condition by a minute particle of one of those 

 metals which range themselves toward the 

 electro-positive end of the scale; so that its 

 affinity for the more electro-negative metals is 

 so greatly exalted that it seizes upon, and is 

 absorbed by their surfaces instantaneously. 



The practical results obtained by using so- 

 dium amalgam, are highly satisfactory and sur- 

 pass any other method. Although compar- 

 atively new, this process is now introduced into 

 almost every gold district, according to the re- 

 ports in many scientific or mining journals. 



The amalgamation of auriferous iron pyrites, 

 such as are found especially in Colorado and 

 Montana, is much more difficult and requires a 

 very careful preparation of the ore, previous to 

 its contact with mercury. The first question to 

 consider, is the state' in which the gold occurs 

 in the pyrites whether as metal or as a sul- 

 phuret. Most writers on the subject accept 

 the first, and if this be correct, the gold must 

 be in exceedingly fine particles, which have to 

 be disclosed and freed, before mercury can act 

 upon them. The ore, therefore, must be very 

 finely pulverized, and to do this, several new 

 machines were invented and tried with more 

 or less success. But, notwithstanding this 

 theory, the amalgamation of raw pyrites, how- 

 ever finely powdered, is so incomplete, that in 

 many cases not over 20 per cent, of the metal 

 is obtained. It was found, that the ore needed 

 to be desulphurized previous to its amalgama- 

 tion, to gain a reasonable percentage of the 

 precious metal. This process has been and 

 still is of immense importance for Colorado, 

 where fuel is rather scarce, and the attention 

 of metallurgists has been especially directed to 

 find a method which requires little fuel. One 

 much in practise, is the apparatus of Keith, in 

 which the ore is blown as a fine dust through 

 a tubular vessel, being heated by the flame of 

 some fuel, brought in contact with the ore. It is 

 reported, that this method has given excellent 

 results. Compared with the amalgamation of 

 the raw ore, it undoubtedly has, but it is not 



