328 Mr R. Adie's Account of Electrical Experiments. 



the galvanometer, was immersed in ordinary fresh water, some dis- 

 tance below the surface. When the water was brought to boil, the 

 indication fell gradually from 50°, until it reached within 5° of zero; 

 on adding cold water containing air, there was a great rise in the 

 action. The fact shewn by this experiment of ebullition destroying 

 the action of the couple, appears to me to be at once conclusive of 

 its requiring oxygen from the atmosphere ; for by boiling all the ab- 

 sorbed air is expelled. When a little pure salt was added to the 

 water, then the arrangement became quite independent of air, and 

 even at 50° temperature, hydrogen was seun to rise slowly from the 

 platina surface. Other metals platinized had the same action ; but 

 when the platina was replaced by pure gold or palladium then at 

 temperatures of the weather, the oxygen of the atmosphere became 

 requisite for their action. In my former communication above re- 

 ferred to, I stated that I found a zinc and silver couple to lose their 

 effect under an exhausted air-pump receiver, whether they were ex- 

 cited by pure or by salt water. At temperatures of the weather 

 this is strictly correct ; but when the test of boiling the salt water 

 was applied, then zinc and silver couples proved to be independent 

 of the oxygen of the atmosphere ; the galvanometer indication rose 

 from 50" to 85°, where it remained so long as the boiling continued. 

 Copper in lieu of silver gave results dilfering merely in degree ; only 

 it is worthy of remark, that the action of a zinc and copper couple 

 in boiling sea water is not so great as in cold sea water holding 

 absorbed air. These results clearly enough shew where the change 

 from atmosphere supported galvanic action passes into one where 

 water is decomposed. In boiling distilled water, or water from the 

 new red sandstone formation, platina and zinc do not act. In salt 

 water at ordinary temperatures, they are independent of the atmo- 

 sphere. In cold salt water, copper, silver, gold or palladium, require 

 air for the support of their action; while in boiling salt water their 

 character changes, and a couple of zinc and copper can slowly act, 

 while silver and less oxidizable metals act rapidly without need of 

 oxygen from the air. 



To ascertain where the oxygen was absorbed in the water battery, 

 two tubes filled with oxygen were inverted over the upper portions 

 of a zinc and platina couple excited by water ; the connection be- 

 twixt the plates was contrived so that it could be made at pleasure, 

 without disturbing the gas tubes. With a broken circuit there was 

 no absorption of oxygen in the tube over the platina plate. When 

 the circuit betwixt the plates was completed, the rate of absorption 

 in the tube containing the zinc decreased a little, while beside the 

 platina plate the rate of absorption now proceeded rapidly, being, 

 when compared with that in the zinc, as 5 to 2. These experiments 

 were for three days each, and similar results were afterwards ob- 

 tained, where a piece of gas coke and a plate of copper were each 

 .substituted for the platina. The rate of 5 to 2 decreases when the 



