130 REPORT — 1861. 



this, much money was spent at the Cwmheisian mines, and very little gold obtained 

 by smelting operations, for reasons which are now not very difficult to understand. 

 Much money was also spent about ten years afterwards at the same place, after 

 settinf the most eminent assayers to work, to prove the truth of ilr. Dean's state- 

 ment, in erecting machinery, which produced even less gold by amalgamation than 

 the former method. Although it was then held as an axiom that gold always 

 exists in a metallic state, that mercmy has always an affinity for gold, and therefore, 

 wherever gold is present in minerals, mercmy will necessai-ily dissolve it, in this 

 instance, however, it did not prove the case, and the result of operations upon 150 

 tons came at length to be considered as an enigmatical faUm-e, as the following 

 extracts from the expeiiments made at the time will show. Here followed a 

 detailed accoimt of experiment No. 7, made on 4J tons of metalliferous minerals 

 which were triturated in 42 lbs. of mercmy. Ten poimds of this on distillation gave 

 70 grains residual metal, containing 18-4 gTalus ot gold. A qualitative analysis of 

 this residual metal gave gold, sUver, lead, bismuth, zinc, arsenic, and also traces of 

 copper and u"on. The distilled mercmy contained traces only of zinc and arsenic. 

 It had been proved before the experiment, and also since, that the 4^ tons of mine- 

 ral contained several ounces of the " Royal metal," but the quicksilver neglected it 

 for associates of less dignity, though inti-insicaUy of more real utility. This, how- 

 ever, was not the result expected. At the Dol-y-fi"wynog mine, about two years 

 aftei-wards, Sh- Charles Price operated similarly upon several tons of material, but 

 with the same provoking failure as before. At present the Clogau mine is the 

 most interesting and profitable. It stands at an elevation of 1000 feet above the 

 level of the sea. The "Saiat Da-vid's" or "Gold Lode" is the most remarkable 

 feature. After giving some descriptions of this mine, he desired to notice espe- 

 cially that this lode is at the jmiction of the Cambrian sandstones and theLingida 

 flags of the Lower Silurian rocks. A quantity of what was called " poor copper 

 ore " was raised from this lode and sold many years since ; but in 1854 the refuse 

 of this " poor copper ore " was examined, and indications of native gold in con- 

 siderable quantities were foimd. Some of this refuse ore was put to the test, and 

 in one instance, to his knowledge, 100 lbs. weight yielded 14^ oimces of gold. Many 

 other experiments have been made by various persons with equal success ; but 

 owing to the uncertainty of the operation of amalgamation on the one hand, and 

 the mines themselves being subject to two Chancery suits on the other, the general 

 value of the lode, in bidk, has not imtil recently been determined. After some 

 observations on the processes of assay — which he did not think would give the 

 approximate value of amiferous minerals, notwithstanding that the contraiy had been 

 asserted by many eminent men — he refeiTed to a series of thirteen experiments made 

 by himself last aiitimm upon 112 poimds of amiferous quartz from the Clogau mine, 

 didy prepared and sampled by Johnson and Son, of Loudon. The whole quantity gave 

 25 oz. 16 dwts. 7 grains of amalgam, and of fine gold, 8 oz. 5 dwts. 19 grains. An 

 authority in such matters had declared the value of the gold by assay to be £9 per 

 cwt., while he declared it to be £30 ; in the latter case samples of 7 lbs. each, instead 

 of the usual 400 grains, had been operated on. He would now state the result of 

 actual working operations for gold at the Clogau mine since the beginning of the 

 year. This statement showed that 207 tons 8 cwt. of quartz gave 1314 oz. of fine 

 gold ; 3 tons of the best of this quartz gave no less than 976'6 oz. of gold. If 

 they added 56 oimces obtained from 5 tons in 1860, it showed a total quantity of 

 1370 ounces of gold from 212 tons of am-iferous mineral, being at the rate of 6^ 

 oimces per ton. This, he believed, was the first instance of a hundi-edweight of 

 gold having been obtained fi-om the crown lands of this countiy, the value of which 

 was £5300. This " Eoyal Mine " paid a royalty of Jj to the' crown. The cost of 

 extraction had been veiy inconsiderable, and there was a probability of an equal 

 yield of gold for some time to come. 



P.S. The total amount raised fi-om this lode to 19th May, 1862, is three hundi-ed- 

 weight. 



On the Details of the Carboniferous Limestone, as laid open ly the Raihvay 

 Cutting and Tunnel near Almondshury , north of Bristol. By — Eich-YED- 

 soN, C.E. {Communicated by Sir R. MTjRCHisoiir.) 

 Geologists obtained a great deal of veiy available and useful knowledge from the 



