514 



THE GEOLOGIST. 



in one instance a hundred pounds weight yielded fourteen and a-half ounces of 



gold. 



This remarkable load has been experimented upon, for limited periods, and 

 in various ways, by several persons since the gold discovery of 1854, and many 

 strings or shoots of gold obtained equally rich ; but, owing to the uncertain 

 operations of amalgamating machines on the one hand, and the mines them- 

 selves being the subject of two chancery suits on the other, the general value 

 of the lode in bulk has not, until recently, been determined. 



The author has for a long time been of opinion that it is impossible to arrive 

 at an approximate value of auriferous minerals in bulk by the ordinary process 

 of assay. Assays are likely to prove delusive, simply on account of the un- 

 equal distribution of the precious metal in the minerals. Many men of great 

 abilities state the contrary ; but they cannot do it for all that ; for, if they 

 caunot obtain a fair sample to assay, it is impossible that the assay to the bulk 

 can be proportional. 



In proof of this the author referred to a record of thirteen experiments 

 made by himself just a year since, upon a hundred and twelve pounds of auri- 

 ferous quartz from the Clogau Mine, part of a stone weighing about four hun- 

 dred weight, which was broken from the lode on Whit Monday, 1860, sent to 

 London, and crushed and sampled by Johnson and Son. 



Dwt. 



Gr. 





Oz. 



Dwt. 



Gr- 



10 



0 of amalgam, 



and fine gold 0 



8 



10 



0 



10 





0 



11 



10 



14 



12 



» 



1 



3 



0 



16 



11 „ 





0 



10 



12 



6 



2 



5j 



1 



4 



5 



13 



4 



5> 



0 



10 



12 



0 



12 



33 



0 



10 



10 



3 



14 



33 



1 



2 



12 



10 



10 



33 



0 



11 



4 



4 



o 



33 



0 



9 



11 



16 



4 



33 



0 



17 



5 



0 



14 



33 



0 



7 



0 



16 



7 



93 



8 



5 



19 



2. 71bs. 



3. 141bs. 



4. 71bs. 



5. 7lbs. } 



6. 7lbs. , 



7. 71bs. 



8. 71bs. 



9. 141bs. 

 1©. 71bs: 



11. 71bs. 



12. 141bs. 



13. 71bs. 



1121bs. 



These experiments were very carefully made, because a gentleman in Lon- 

 don, of very high standing in such matters, had declared the value of the ore 

 by assay to be nine pounds only per hundred weight, whilst the author had 

 ventured to declare it worth thirty pounds. He happened to be right, because 

 trials of seven pounds weight are likely to be nearer the mark than those of 

 only four hundred grains. 



Lastly, he stated briefly the result of actual working operations for gold at 

 the Clogau Mine, since the beginning of the present year. 



Tous. Cwts. Ouuces. Dwts. 



191 11 of good quartz, gave of gold 241 14 



12 17 of better „ „ „ 96 0 



3 0 of best „ „ „ 976 6 



8 from the bulk of the lode, gave 1314 



0 



To this, if we add fifty-six ounces, the result of experiments in 1860 upon five 

 tons, wo have a total quantity of one thousand three hundred and seventy 



