352 Mr R. Adie on Thermo- Electrical Experiments. 



or where there is no vegetation to protect the surface against 

 the influence of atmospheric agents. 



Explanation of the Figures in Plate III. 



Fig. 1. Contorsions of the icy masses near the north edge of the glacier 



of the Oberaar, 5th August 1842. 

 Fig. 2. Contorsions in the glacier of the Unteraar, near M. Agassiz's 



gallery, 1st August 1842. 

 Fig. 3. Contorsions in the glacier of Aletsch, near Lake Moriel, l7th 



July 1841. 

 Fig. 4. Contorsions in the glacier of Aletsch, half a league above Lalce 



Moriel, 14th August 1841. 

 Fig. 5. Lower extremity of the western arm of the glacier of Viesch, 



30th June 1841. 

 Fig. 6. Limestone rock, polished, furrowed, and striated, in the valley 



of Tamina, a league beyond the Baths oif Pfeffers. 

 — Geological Society of France. Seance l^th Janvier 1846. 



An Account of T her tno- Electrical Experiments. By Mr R. 

 Adie, Liverpool. Communicated by the Author. 



In the present communication, I propose to resume the considera- 

 tion of some of those thermo-electrical experiments, which were pub- 

 lished in Nos. 70 and 71 of this Journal, chiefly for the purpose of 

 shewing that, in the joints of thermo-electric couples, molecular ac- 

 tion has no power to develop a current of electricity ^ U7iless the 

 bars are unequally heated. 



Referring to the above mentioned papers for several facts which 

 go to shew that there is a molecular change in a joint, which has been 

 long engaged developing a thermo-electric current, I have since en- 

 deavoured to find a similar change in a joint which has been long 

 equally heated at a temperature a few degrees below boiling water. 

 One series of experiments extended through a period of sixteen 

 months, yet in no case have I met with a molecular change in the 

 joints of equally heated thermo-electric couples. From this we 

 should infer that unequal heating is necessary to produce the mole- 

 cular change ; then, reasoning from analogy, we should expect to 

 find that molecular change, without unequal heating, should, in like 

 manner, fail to throw an electrical current into circulation, a result 

 M'hich I shall endeavour to establish, by briefly running over a few 

 experiments. 



In No. 74, p. 298, I have stated that I could produce no effect 

 on the galvanometer by the slow mechanical fracture of the solder- 

 ing of a thermo joint. The following is a much more satisfactory 

 method of testing this point. A couple of bismuth and lead were 

 connected in the usual manner with the galvanometer, and their 



