114 Chronicles of Science. [Jan. 



colate through the mass. After this has been done several times, the 

 fluid should be run off into separate vats, and the metals which it 

 contains extracted. If silver is present, an excess of salt must be used 

 in the process, for the purpose of holding in solution any chloride of 

 silver that may have been formed. 



Blades of copper placed in the saline solution precipitate the 

 silver ; then the copper is thrown down by metallic iron ; and the 

 gold is then extracted by adding to the fluid a concentrated solution of 

 the sulphate of the protoxide of iron (green copperas), which throws 

 down the precious metal in a metallic form. 



In the Mendip Hills, mining operations on a very extensive scale 

 were formerly prosecuted. So important was the Myne-deeps that a 

 special code of laws was formed for the regulation of the mineral 

 works upon those hills. Old slags and slimes are found spread over 

 extensive districts, and these for some years have been turned to some 

 small account. More important operations are just started. At the 

 St. Cuthbert Lead Works near Wells, five new Catellan furnaces, a 

 30-inch cylinder steam-engine, two blast cylinders, and one of Ben- 

 nett's condensers, are in process of erection. About 150 tons of good 

 soft pig lead have been produced from this old debris within the last 

 six months, but it is calculated that the new furnaces and blowing 

 apparatus will yield 120 tons of pig lead a month. 



The importance of the discovery of coal in our colonies cannot .be 

 overestimated. The following abstract of the Eeport of the official 

 examiner, Mr. Mackenzie, of the coal-fields of the Illawarra district to 

 the South of Sydney, is, therefore, of considerable interest. It has always 

 been suspected that the Northern coal-field dipped under Sydney and 

 reappeared at Wollongong. By a careful examination along the coasts 

 of the superimposed strata, the connection of the two coal-fields has 

 been established. The lay of the Wollongong coal-measures is trace- 

 able with tolerable clearness along the face of the sea-cliff. The top 

 seam vanishes below the water-line at a point about thirty-four miles 

 South of Sydney. It has been identified as reappearing above the 

 water at Tuggerat Beach to the North of Sydney, and about seven 

 miles South of Lake Macquarie. The Tuggerat Beach coal lies above 

 the Lake Macquarie coal, and its identification with the Wollongong 

 coal enables the section of the coal basin to be so far completed that 

 the order of superposition between the Southern and Northern mea- 

 sures is determined. Two other outlying coal-measures are known to 

 exist, one at Mittagong further South than Wollongong, and one 

 above Stroud, North of Newcastle. 



There are said to be twenty-six different seams of coal, averaging 

 three feet in thickness, or containing 157 feet in thickness of coal. 

 The strata in which these seams are imbedded represent a depth of 

 5,000 feet. 



The Official Eeport concludes with the remark that these twenty- 

 six seams do not form an exhaustive list of coal-measures, but include 

 only those which have been so far examined as to be placed in their 

 order. The collocation of other known seams awaits further in- 

 vestigation. 



