406 TENTH ANNUAL REPORT OF 



§45. EO^eds of the gas pile. — Grove obtained the following effects 

 with a gas battery of 50 elements : 



1. A shock which could be felt by five persons joining hands. 



2. In a moderately sensitive galvanometer, the current produced a 

 constant deflection of 60°. 



3. Considerable divergence of a gold leaf electroscope. 



4. Between charcoal points a spark visible in full day-light. 



5. Electrolytic decomposition of iodide of potassium and acidified 

 water. 



To produce a sensible decomposition of water, from cells of the above 

 described construction, four elements are sufficient. A single cell de- 

 composes iodide of potassium, 



A circuit of ten elements of this kind with dilute sulphuric acid of 

 the spec. grav. 1.2, and filled alternately with hydrogen and oxygen, 

 was closed with an interposed voltameter and lett standing 36 hours. 

 At the end of this time 2.1 cubic inches of detonating gas had been 

 developed ; in each of the hydrogen tubes 1.5 cubic inches had dis- 

 appeared ; in each of the oxygen tubes 0.7 cubic inch; thus, to- 

 gether, 2.2 cubic inches of gas had disappeared. The difference 

 (2.2 to 2.1) is due to a small absorption of the oxygen by the water. 

 If a sensible current is to be produced, the platinised platinum 

 plates must not be wholly immersed beneath the surface of the water, 

 but they must extend partly out of the liquid into the atmosphere of gas. 

 A battery, whose tubes were charged alternately with hydrogen 

 and dilute nitric acid, gave a current, and three pairs were sufficient 

 to decompose water in an interposed voltameter. 



The gas pile yields a very powerful current if chlorine is substituted 

 for oxygen. A chlorine and hydrogen battery of two elements is 

 sufficient to decompose water between platinum plates. 

 Carbonic oxide gas acts in the gas pile like hydrogen. ^ 

 Other gases — for example, nitrogen — are absolutely without effect. 

 For instance, place a mixture of nitrogen and oxygen in one tube, 

 and hydrogen in the other ; after closing the circuit all the oxygen is 

 gradually but completely absorbed, Avhile the nitrogen remains the 

 same. Grove's proposition to apply the gas pile in eudiometrical 

 experiments is based upon this. 



In a second memoir, which may be found in Poggendorff's Annalen, 

 (2to Erganzungsbande, seite 407,) Grove describes the following re- 

 markable experiment. 



One of the tubes of the gas pile was charged with oxygen ; in the other 



a weighed piece of phosphorus was placed by means of a small glass 



Fie .T3 ^"P fastened to a glass rod, as represented in Fig. 32, and then 



r-f the tube was partially filled with nitrogen. The apparatus 



Y indicated a current by an interposed galvanometer. After 



being closed four months, during which time the galvanometer 



constantly indicated a current, the water had increased in the 



oxygen tube one cubic inch, but not at all in the nitrogen tube ; 



the piece of phosphorus, on the other hand, had become 0.4 



grain lighter. • 



This result is easily explained ; the vapor of phosphorus 

 was diffused in the atmosphere of nitrogen, and this acted 

 exactly like hydrogen in the ordinary gas battery. 



