56 Mr. W. G. Armstrong on the Electricity of Effluent Ste am 



order to acquire a neut}-al or saturated state, and when by 

 condensation it again becomes water, the electricity thus ab- 

 sorbed will necessarily be set free ; and hence the positive 

 electricity which we find in the jet. 



Upon the same principle, if the boiler be insulated, the water, 

 the boiler, and the uncondensed steam, will all be rendered 

 negative, provided the steam be permitted to escape, but not 

 otherwise; for if the steam be confined within the limits of the 

 boiler, the evaporation will not be attended with any increase 

 of volume, and the absorption of electricity will in consequence 

 be prevented. In all these respects the theory exactly ac- 

 cords with observation. 



I am bound, however, to admit that the explanation which 

 I have here advanced, involves certain conditions which ap- 

 pear somewhat at variance with experiment. In the first 

 place the condensation of a given weight of loiso-jiressure 

 steam ought, if the absorption of electricity depends upon 

 increase of volume, to liberate more positive electricity than 

 the condensation of an equal weight of high-pressure steam ; 

 and in the second place, the expansion of steam from one de- 

 gree of density to another should, on the same principle, be 

 accompanied by a development of negative electricity. Not- 

 withstanding, however, what has been advanced in favour of 

 high-pressure steam containing more electricity than steam 

 of low density, I think it quite possible that the reverse of 

 this may be the fact; for it is not at all improbable that a low- 

 pressure jet may conduct so large a portion of its electricity 

 back again to the boiler as to make it appear to liberate 

 less electricity than a high-pressure jet, while in reality it may 

 develope a great deal more. It is quite reasonable to suppose 

 that the conducting power of steam should be increased by 

 rarefaction ; and besides, in order to make a fair comparison 

 between the quantities of electricity liberated by two jets of 

 steam, it is indispensable that ihey should discharge equal 

 locights in c(]ual times, and to effect this condition it is neces- 

 sary to discharge a much larger volume when the steam is of 

 low pressure, than when it is ofgreat density, and by so doing 

 we unavoidably increase the quantity of unvaporized water 

 swept out of the boiler in conjunction with the steam, and 

 thus improve the communication between the jet and the 

 boiler, and at the same time cause a considerable dispersion 

 of the electricity. 



With regard to expansion producing negative electricity, 

 I have certainly never detected such a result ; but I much 

 (juestion whether in any of the above experiments expansion 

 was effected without an aqueous condensation sufficient to 



