Mr. Crosse on the Tension Spark from the Voltaic Battery. 2 1 5 



and especially for the latter, on account of the extremely high 

 temperature it is capable of producing. 



I repeat, that if this combustible prove homogeneous and of 

 equal quality in every part of the deposit, the discovery is one 

 of great importance for the reduction of ores and the quality 

 of the resulting products. 



Dr. Schafhaeutl of Munich, now or lately residing at 

 Swansea, has analysed for the Kilgetty Company, two samples 

 of the Pembrokeshire coal ; the average specific gravity he 

 states to be 1*413. 



1. 2. 



Carbon 92*42 94*100 



Hydrogen 3*37 2*390 



Oxygen 1*43 1*336 



Nitrogen 1*05 *874 



Sulphur *12 



Earthy matter 1*61 *068 



Alumina *478 



Silica -190 



Iron -264 



Water *300 



100 100 



Pembrey, Carmarthenshire. 



XX XL On the Tension Spark from the Voltaic Battery. By 

 Andrew Crosse, Esq. Communicated in a Letter to John 

 P. Gassiot, F.R.S. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 

 T^HE inclosed communication from my friend Andrew 

 Crosse, Esq., may perhaps be interesting to the readers 

 of the Philosophical Magazine; the paper he alludes to is one 

 I communicated to the Royal Society, and which was ho- 

 noured by a place in their Transactions of this year. 



I am, Gentlemen, yours, &c. 

 Clapham Common, Aug. 3, 1840. John P. GASSIOT. 



My dear Sir, 

 I return you my best thanks for your paper on the voltaic 

 spark, &c. ; I have read it with attention, and was much inter- 

 ested by its perusal, particularly by that part which relates to 

 Zamboni's pile. I once had a cork ball kept vibrating be- 

 tween the poles of four columns of De Luc's pile, without 

 cessation, for upwards of twelve years ! Now for the possibi- 



