98 Mr R. Adie's Experiments with Thermo- and 



tliermo-electrical energy. With the arrangement described (9), the rate 

 of decomposition per diem by the battery was taken at the end of 90 

 days' continued action, when I was certain, from previous experiment, 

 that the joints had greatly changed ; they were then resoldered, and the 

 voltameter attached, in as nearly as practicable the same condition as for 

 the first rate. This experiment shewed no alteration in the rate, from 

 wliich we may infer, that thermo-electrical batteries are capable, at mo- 

 derate temperatures, to generate their currents for almost an indefinite 

 length of time. 



Two single pairs of antimony and bismuth 

 bars, fig. 5, decomposed sulphate of copper, 

 and Argento-cyanide of potassium, for two 

 months respectively. 



a antimony bar, 6 bismuth bar, weight of 

 the pair 19 grains, f projecting point made 

 to touch a blue flame, e e the poles, d c de- 

 composing cell same as fig. 4. 



A thermo couple of antimony and bismuth bars, soldered by pure bis- 

 muth, and excited like battery described (9) for 120 days, separated in 

 the joints at the end of this period, by a light touch ; and a small quantity 

 of the bismuth at the part where it has been in contact with the antimony, 

 rubbed off in a pulverulent form. The antimony at the soldering was un- 

 altered. This experiment appears to me to be of value, to shew the na- 

 ture of the change in metals attendant on thermo-electrical actions. 



31. I now entered on a series of experiments, to ascertain the altera- 

 tions in the texture of metals, and their changes in density from anneal- 

 ing, as shewn by the balance, their fractures, and the galvanometer ; of 

 these it will be sufficient here briefly to notice the results. 



Cast bars of antimony, bismuth, and zinc, never changed their fractures, 

 although annealed for four months at a temperature little lower than 

 their melting heat. The grain of some of the specimens tried, was of a 

 fine unnatural texture, occasioned by casting in a cold metal mould, yet 

 the annealing made no alteration in this grain. Rolled zinc, where the 

 crystals have been bruised, undergoes a marked change by annealing at 

 temperatures 30° higher than our summer weather ; but the extent of 

 the change to a larger grain is much governed by the annealing tempera- 

 ture ; thus, with a temperature of 150°, it is impossible to produce the 

 same size of grain as 250° gives, although the time of annealing the first 

 is prolonged ever so much beyond the period allowed the second ; but 

 annealings at low temperatures required more time for the full develop- 

 ment of their change than was necessary for higher temperatures. 



With iron I have found the same order to prevail in the results ; but 

 it requires high temperatures for all those changes, to be recognised by 

 tho balance or the fracture. Iron softened at 400° for 3 months, did 

 not sensibly change the specific gravity. Soft steel retains its density 

 with remarkable uniformity ; although, in hardening, the loss exceeds 



