200 Messrs. Wright and Thompson on the Determination of 
trace out whether the different halogen salts exhibit analogy 
with these oxygen-acid salts, or whether they differ materially 
amongst themselves, a number of cells were examined con- 
taining various metals immersed in solutions of their respective 
bromides of constant strength °25MBr, 100 H,0, or in magmas 
of their bromides immersed in zinc-bromide solution of this 
strength (saving in the case of lead bromide, where the sparing 
solubility necessitated the use of weaker solutions). 
I. Cadmium. 
The following values were obtained with zinc-cadmium- 
bromide cells :— 
Maximinnt, sei men 2. rolls 
Manian eile ese bonal: 
Wyeramed 6520 hme he oe a odes 
Probable error 29). 5 0014 
Julius Thomsen finds the values Zn, Br, aq. = 90960, and 
Cd, Br, aq.=75640; whence Eg=-338, corresponding with 
15320 gramme-degrees. Hence 
E —Hy= — 023 3 
that is, the thermovoltaic constant for electro-cadmium in 
bromide solution of strength :25CdBr, 100 H,O is a small 
negative quantity, not quite so large numerically as that for 
the corresponding chloride solution (viz. —-036). 
II. Silver. 
198. The following values were obtained with cells set up 
with amalgamated zinc opposed to electro-silver immersed in 
a magma of freshly precipitated well-washed silver bromide 
suspended in zinc-bromide solution, the solution-strength 
throughout being °25ZnBr, 100 H,0. 
Maximus 5.2 eaten ie ae ee 
Noinimunat sere ee Om 
AWerave: eis ie a tay SOO 
Probable error. . . .+:0012 
Julius Thomsen finds Ag,, Br, = 45400; whence Eg=1-005, 
corresponding with 45560 gramme-degrees. Hence 
Py He 090) 
that is, the thermovoltaic constant for silver in contact with 
silver bromide suspended in zinc-bromide solution is a notable 
negative quantity, slightly less numerically than the corre- 
sponding value for silver chloride suspended in equally strong 
zinc-chloride solution (viz. — 112). 
