Clw.ii'jes prodarcd in Matter hy Eledric Waves. 



403 



111 the above it has been assumed that the reaction of B variety is 

 opposite to that of A. As previously mentioned, in working with a 

 silver receiver I found it, when fresh, exhibiting at first a diminution 

 and, subsequently, an increase of resistance. The anomalous action 

 may be explained by supposing the normal fresh silver Ag to be 

 positive, and the radiation product Ag' negative. These two varieties 

 Avould thus give rise to opposite reactions. To justify the assumptions 

 made above, it became necessary to obtain by some other means a 

 variety of silver Ag', analogous to the hypothetical negative variety.] 



Tiro Varieties of Silcer. 



After many unsuccessful attempts, I at last obtained a variety of silver 

 which gives a moderately negative reaction (increase of resistance). 

 Silver chloride was first precipitated by the addition of dilute hydro- 

 chloric acid to silver iiitrate solution. The precipitate was then reduced 

 to metallic silver by zinc filings, the excess of zinc being dissolved off 

 by the action of HCl. This form of silver gives a negative reaction. 

 Direct 23recipitation of silver produced by dipping a piece of zinc in 

 AgNOs solution gives a positive variety. The negative product Ag' is 

 perhaps better formed at relatively low temperatures, for the products 

 obtained on certain warm days, the thermometer registering 27' C, 

 were very feebly negative, and passed into the positive state after an 

 inteival of twenty-four hours. But on cold days (temperature = 22° C.) 

 the products obtained were stable. I have specimens which have kept 

 the negative property unimpaired for nearly three months. The nega- 

 tive property is not due to any accidental impurity, for pm^e silver 

 obtained by Stas' method also gave the negative reaction. The 

 negative reaction may, however, be supposed to be due to a thin film of 

 chloride formed diu'ing reduction. I washed the Ag' with XH3, then 

 with water, and, after drying, the result was still a negative reaction. 

 I then carried out a parallel set of experiments with ordinary silver 

 filings. Two separate quantities were taken ; one was shaken with only 

 HCl, the other was mixed with zinc filings, and the excess of zinc was 

 dissolved oft' ^Wth HCl ; the two specimens were then washed and dried. 

 Both gave the positive reaction of ordinary silver. The above experi- 

 ments are interesting for the production, by chemical means, of an 

 allotropic variety analogous to the transitory radiation product. 



There are other differences of electric behaviour between Ag and 

 Ag' ; for instance, when made into a voltaic cell, the two varieties give 

 a P.D. of about 0'12 volt. There are other interesting peculiarities 

 about this cell, the consideration of which is postponed to a futiu-e 

 occasion. 



