Constitution of Isomeric Solutions. 301 



The difference between the numbers obtained in this case 

 and in Exps. 5, 13, and 14 is not sufficient to prove that the 

 cooling had any real effect upon the amount of energy. 



Influence of Light. 



Experiment 16. — A solution of the mixture of sodium sul- 

 phate and nitric acid was prepared from diluted ingredients 

 which, when added together, produced a liquid containing 1 

 grain of the mixture in 1550 grains of water. Its voltaic 

 energy was 



Between 73,810 and 81,578 at 18° C. Average 77,694. 



After standing the liquid in the dark during five days, its 

 voltaic energy was 



Between 57,407 and 63,786 at 12° C. Average 60,596 

 (see also " Influence of Time ") . 



A second portion of the same prepared solution was ex- 

 posed in a colourless glass bottle to diffused daylight during 

 the same period. Its voltaic energy then was 



Between 58,270 and 64,583 at 12° C. Average 61,426. 



A third portion, the energy of which at the outset was 



Between 69,160 and 76,001 at 25° 0. Average 72,598, 



was exposed in a similar bottle to direct sunlight during five 

 days; its energy was then reduced to 



Between 43,055 and 46,407 at 20° 0. Average 44,721. 



In these experiments daylight had much less effect than 

 sunlight, probably in consequence of the higher temperature 

 in the latter case. 



Influence of Magneto-Electric Induction. 



Experiment 17. — A portion of the original solution " A " 

 possessing an average voltaic energy == 75,860 at 23°*5 C. 

 was placed in an annular glass vessel surrounding a voltaic 

 coil, and a strong and rapidly intermittent current from two 

 large Grove's elements passed through the coil during one 

 hour, and the voltaic energy again measured ; it was 



Between 57,407 and 63,786 at 26° C. Average 60,596. 



To ascertain whether the change was due to rise of tem- 

 perature from the heat of the coil, a similar portion of the 

 original liquid was kept during one hour at the same average 

 temperature ; its average voltaic energy had then been 

 similarly reduced to 60,596. Magneto-electric induction 

 therefore had no manifest effect. 



Phil. Mag. S. 5. Vol. 28. No. 173. Oct. 1889. Z 



