M. Peltier on iJie Electricity of Steam. 101 



perfectly even. This collective movement lasts but a short time ; 

 several others established themselvesin the interior; weseethem 

 jostle one another, press on each other in different directions, 

 move in array again together once more, then again to divide 

 themselves. 'At last the movement slackens : the drop, which 

 until then had retained its globular form and had not moist- 

 ened the platina, flattens, wets it, and evaporates all at once, 

 without any electricity having been produced, if distilled 

 water and a clean crucible have been used. 



If instead of pure water a weak solution of sea salt be used, 

 the effect will be the same the first time ; but the salt left by 

 the water having formed a slight layer on the platina, is 

 again taken up by the water used for the succeeding experi- 

 ment : the strength of the solution thus increases, and when 

 the drop is diminished two-thirds it is become almost opake ; a 

 multitude of minute bodies are seen swimming in the inside, 

 and soon after some decrepitations are heard, accompanied 

 with saline projections. At this moment the needle of the 

 electrometer indicates a negative tension. If the platina has 

 become cool enough to admit of moistening, the decrepitation 

 ceases, the drop spreads, and it is immediately transformed 

 into vapour ; the electricity which had just been developed 

 during the decrepitation, instead of being doubled by this 

 sudden change into vapour, disappears with the vapour, which 

 carries it off" with it. The saline layer being increased, the 

 effect at the third experiment is greater ; the decrepitation 

 is stronger, and the needle is projected to a distance. Thus, 

 before and after the decrepitation there is no electricity pro- 

 duced ; the instrument remains mute, whatever be the quantity 

 of vapour produced. 



From the preceding observation, it was natural to suppose 

 that the salt, being substituted for the salt water, would pro- 

 duce the same effect; this is what the experiment has verified. 

 The chloride of sodium decrepitating without aqueous fusion, 

 the water interposed plays the part of saturated solution, and 

 sets in motion the needle of the electrometer. If it be a salt 

 containing water of crystallization, as the nitrate of ammonia 

 so easy of decomposition, there is at first the aqueous fusion, a 

 great evaporation without producing electricity, then at last 

 comes the decrepitation, and the needle is strongly projected 

 by negative electricity. 



It is then at the moment of the separation of the combined 

 molecules of water that electricity is produced ; it is at the 

 moment that a chemical decomposition takes j)lacc, and not 

 during the separation of the excess of water. Tiie appli- 

 cation of these experiments to the phaenomenon observed 



