Dec, 1904.1 



KNOWLEDGE & SCIENTIFIC NEWS. 



283 



lollDwiiiy sul)st;inccs ananyccl in ihc posilii)iis as 

 shown in the diagram. These were coveicd by a sheet 



Our lirsl experiment willi the /iiir-coppci- ci uple 

 beneath llie support C proihiccd llie aici>ii\p:mvini; re- 

 sult (see V'lg. J,], 'llie exposure lasted <le\iii days 



.^-^ 



Wax. 



Amalgam. 



Match. 



^CL 



of ordinary note-paper, and on the top was placed 

 (film downwards) a photographic plate. We left it 

 from July 28 until .September 6 (40 davs). 



Fig. 1.— July zS-Sept. 6, 1004. 40 days. 



It will be observed that the general illuniinatiui: 

 comes from the centre of the plate directly over the 

 sodium amalgam into which water had been allowed to 

 trickle. The obstacles were pieces of plain and per- 

 forated zinc, copper, and tinned iron. In order to 

 investigate the cause of this action we exposed our 

 materials for a period of twenty-one days to the radio- 

 acti\e effects of gas mantles, and then tried their 

 effect, as before, for ten days (.September 6 to .Septem- 

 ber 16). When the plate was developed it appeared 

 quite clear. Incidentally we observed that unused gas 

 mantles have precisely the same effect as the used gas 

 mantles. 



Our next experiments were conducted in an iron 

 box, blackened and made thoroughly light-tight. A 

 section through the apparatus is given in I'ig. 2. 



c. 



A, vessels containing chemical reagents. 



B, wool connecting them. 



C, iron support. 



D, note-paper. 



E, obstacles. 



F, plate (protected) with film downwards. 



G, thick sheets of red paper. 



Fig. .?.- Sept. 20-Oct. I. 1004. 



days. Cii Zn in Sulphitric Acid. 



(September 20-October i). Hotli the pieces ul zinc 

 have become sources of light, llins [)ro<lucing an effect 

 entirely different from our other results. 



It may be stated here that the pieces of zinc used had 

 not been in use before for any previous experiments. 

 After an exposure of thirteen days phosphorus in water 

 gave no result whatever. Our next plate is the result 



Fig. 4. Sept. 2.i-0ct. 3, iyo4, loday.'i. Ammonia and llydrocliloric 

 Acid ifuminKi. 



of exposure to fuming ammonia ;in(l hydrochloric acid. 

 In s[Mte of our precaulioiis to the contr.iry the liquid 

 managed to crawl up to the plate and affect it as 

 shown above. 



It then occurred to us to try the elfect of a double 

 reaction, such as takes place when calcium carbide is 

 treated with water. 



(i) CaC, + H.,0 = CaO + C,H, 

 (2) CaO 4- H.O ^ Ca(() II), 



After an exposure of only two days tin- plate was 

 developed with the accompanying result. The light 

 [)ortion was the part immediatelv over the vessel con- 

 taining the calcium carbide. i'he lines were on the 



