Mr. Pattinson's Experiments on the Electricity of Steam. 457 



allowed the steam to expand in a very great degree before it 

 issued into the air, and caused it to be discharged in the state 

 of low-pressure steam; but no diminution of electricity could 

 be perceived in the jet, when thus attenuated; so that the elec- 

 trical development does not appear to depend upon the de- 

 gree of violence with which the steam comes in contact with 

 the atmosphere. 



The entire absence of negative electricity seemed to pre- 

 clude the possibility of the phenomena arising from expan- 

 sion, and the only remaining supposition appeared to be, that 

 the condensation which took place in the jet, set free the 

 electricity which the steam had absorbed in the process of 

 evaporation. This supposition had been previously rendered 

 probable, when it was discovered that the upper and most 

 opake part of the jet yielded the most electricity, although 

 I was at first inclined to attribute that circumstance to the 

 dampness of the steam, in that part of the jet, rendering it a 

 better conductor, and causing it to part more readily with its 

 electricity. Experiments were next, therefore, commenced to 

 ascertain the effect of insulating the boiler, and wholly con- 

 densing the steam ; but these require repetition before they 

 can be much relied upon. The great difficulty is to effect 

 insulation amidst so much moisture, but I have no doubt 

 that with a little perseverance this object will be accom- 

 plished, and I trust I shall be able to furnish, in time for in- 

 sertion in the next Number of the Philosophical Magazine, 

 such further results as will set the question at rest. 



I am, yours, &c. 



Newcastle upon-Tyne, Nov. 18, 1840. Wm. Geo. Armstrong. 



L X V 1 1 . Furth er Experiments on the Electricity of Steam, 

 By H. L. Pattinson, Esq., F.G.S. 



To the Editors of the Philosophical Magazine and Journal, 



Gentlemen, 

 CINCE my last letter to you, dated the 19th ult. (pub- 

 ^ lislied at p. 375 of this volume), relative to the electricity 

 of steam issuing from two boilers at Cramlington Colliery, 

 the subject has been further pursued both by myself and 

 others, and sparks have been obtained from the steam of va- 

 rious boilers, in every direction. The mode of operating has 

 generally been that described in my letter, viz. suffering the 

 steam to escape from the safety-valve of the boiler tried, and 

 testing its electricity by holding in it a shovel or an iron rod, 

 the operator standing upon an insulating stool. Sometimes 

 the indications have been very slight, and sometimes there 



