O'Reilly — Notes on some Assays for Gold, etc. 453 



tions. As such analyses or assays are costly, and even tedious in 

 many cases, they are not so often resorted to as is desirable — 

 explorers more generally basing their conclusions on washings or 

 pannings of the ground or rock being examined. This method, 

 excellent in skilful hands, when applied to rock containing free gold, 

 and valuable on account of its simplicity and quickness, cannot 

 give satisfactory results when the gold is in combination with 

 other metals, and therefore it has been found advantageous, in 

 those countries where exploration is being carried on with the 

 greatest activity and intelligence, to facilitate for explorers access 

 to laboratories, wherein careful determinations of the gold and 

 associated metals are made, so that research being continually 

 guided, it can be pushed on with both activity and a clear know- 

 ledge of the ground being operated on. 



Influenced by considerations of this nature, I was led to ex- 

 amine and to have assayed during the year 1888 and the com- 

 mencement of 1889, various rocks occurring in the vicinity of Dublin, 

 with a view to ascertaining whether they contain gold, and also in 

 what quantity, so as to be guided as to the existence of rocks 

 which might be found to present points of concentration of the 

 metal capable of being worked profitably — that is, I proposed to 

 proceed from the general to the particular, and, having traced the 

 existence of gold in several rocks, to endeavour to arrive at a 

 conclusion as to the existence of the metal in greater quantity in 

 certain of them, pushing on, then, the inquiry and endeavouring to 

 define localities likely to show gold in paying quantities. 



The assays were made by Mr. F. Claudet of Coleman-street, 

 London, who was good enough, at my request, to take particular 

 care in determining traces of gold, since, in nearly every case, the 

 most to be expected from the nature of the rock submitted for 

 assay would be a trace of the metal, if any. 



The first rock submitted to him was the stone being used for 

 metalling the streets by the Corporation, and which I had fre- 

 quent occasion to see laid down between Baggot- street Bridge and 

 Stephen's Green, and in the neighbouring streets. This stone — 

 a greenstone or diorite — comes from the quarries about Montpelier 

 and Bohernabreena ; it is very tough, sometimes porphyritic, and 

 nearly always contains iron pyrites. From time to time, during 

 the course of six or eight months, and at various points, I had 



