134; Dr. Aquila Smith on Irish Tin Ore. 



the air was discharged, as to yield sparks fully a quarter of 

 an inch long. I afterwards tried the same experimenta great 

 number of times, and, strange to say, the electricity of the 

 vessel, though generally negative, occasionally proved to be 

 positive. Sometimes the electricity was very strong, and some- 

 times very weak, and frequently I could get no electricity at 

 all. By means of an insulated conductor terminating in a 

 number of points, I also obtained electricity from the ejected 

 air, and found it to be positive every time I tried it. 



I more frequently succeeded in producing an electrical de- 

 velopment when the receiver was cold, and contained a little 

 moisture, than when it was warm and dry, so that it is not 

 improbable that evaporation may even here be the source of 

 the electricity. I am by no means sure, however, that my better 

 success when the receiver was cold and damp, was not mere 

 chance, and I only mention the circumstance as a suggestion 

 to persons who may think proper to repeat the experiment. 



Newcastle-upon-Tyne, Wm. Geo. AkmSTRONG. 



Jan, 23, 1841. 



XXVIII. On Irish Tin Ore. By Aquila Smith, Esq., 

 M.D., M.R.I.A.* 

 T^HE question has been often asked, is tin ore found in 

 ■*- Ireland? and I believe the only I'eply which could be 

 given is, that it was said to have been found in the county of 

 Wicklow, about the year 1796, when the gold mines were 

 worked on account of the Government. 



In the first report on the working of the gold mines, drawn 

 up by Messrs. Mills, King, and Weavei', dated 1st August, 

 1801, and published in the second volume of the Transactions 

 of the Dublin Society, the directors state, that " in every in- 

 stance, where the gold has been found, there have been also 

 found fragments of magiietic iron ore, and quartz containing 

 chlorite, iron ochre, and viartial pyrites, attended, moie particu- 

 larly at the works of Ballinvally (on the north-east declivity of 

 Croaghan mountain), with specula iron ore, brown and red iron- 

 stone, ti7i-sto?ie crystals, wolfram, and gray ore of mangatiese " 

 (Partii. p. 147.). 



Here we find the existence of " tin-stone crystals," an- 

 nounced for the first time in Ireland ; and, strange to say, its 

 discovery does not appear to have attracted any attention in a 

 commercial point of view, nor even to have been sought for 

 as a curiosity by the mineralogists of that time ; for although 

 many minerals newly discovered in Ireland are briefly de- 



* Read before the Geological Society of Dublin, Wednesday, December 

 9th, 1840} and now communicated by the Author. 



