DIVISIBILITY OF GOLD AND OTHER METALS. 75 



object of experiment, or as incidental to other investigations), and 

 to present them in a condensed Ibrm to the readers of The Popular 

 Science Monthly. 



Some of these experiments (notably those of Faraday) present 

 the curious anomaly of revealing to the physical sense of sight 

 particles of matter which are almost too infinitesimal for the mind's 

 eye to conceive, thus seeming to reverse the order of scientific inves- 

 tigation which usually prolongs the mental vision far beyond the region 

 of possible physical revelation. 



The experiments to be described have been arranged in the fol- 

 lowing order: 



1. On the natural dissemination of gold. 



2. Beating into thin leaves. 



3. Faraday's researches. 



4. Depositing by the galvanic battery. 



5. Vaporization by the electric spark. 



Some years since a very interesting series of experiments was 

 made by the late Mr. J. R. Eckfeldt, then chief-assayer of the mint 

 at Philadelphia, and his associate, Mr. W. E. DuBois (the present 

 incumbent), upon the "l^atural Dissemination of Gold." The results 

 were presented to the Amei'ican Philosophical Society, in the form 

 of a paper, by Mr. DuBois, and j)ublished in their " Proceedings " 

 of June 21, 1861. 



The precious metal was found disseminated in marvelously fine 

 division through a number of substances where its existence had not 

 been previously suspected. 



In the clay of which the Philadelphia bricks are made, gold was 

 found in the proportion of about forty cents' worth to the ton. 

 Each brick contains a sufficient amount of gold to make a glittering 

 show of two square inches, if brought to the surface in the form of 

 leaf. 



An estimate of the thickness of the bed of clay under the city 

 revealed the startling fact that more gold lies securely locked up in 

 it than has been procured, according to the statistics, from Aus- 

 tralia and California. A specimen of galena fi'om Buck's County, 

 Pennsylvania, yielded gold in the proportion of one part of gold in 

 six million two hundred and twenty thousand (6,220,000) parts of ore ; 

 not quite ten cents to the ton. The report of these experiments 

 concludes as follows : " Of this we may be confident, that the atoms 

 of gold are homogeneously and equably dispersed through the clay, 

 or other matrix; but by what natural process or for what final cause 

 these fine particles should be thus diflused, seems quite beyond the 

 reach of human philosophy." 



The remarkable malleability of fine gold was a property well 

 known to the ancients. Homer refers to the art of gold-beating, 

 and Pliny mentions that an ounce of gold was beaten into seven 



