262 Harriny—The Action of Heat on the Absorption Spectra and 
It is necessary here to give an account of the hydrates of nickel bromide and 
iodide, in order to explain the nature of the action of heat upon their absorption 
spectra and the constitution of their solutions. 
Preparation and Analysis. Nickel Bromide and its Hydrates. 
These salts have been but imperfectly described by Berthemot* and by 
Rammelsberg.t 
The analysis of the latter lead to a formula for the crystallized hydrated salt 
of NiBr,-3H,O. I have not obtained this as a crystallized salt. 
The bromide was prepared in a similar manner to that described for the 
preparation of haloid cobalt salts.{ 
Clippings of rolled nickel were placed in a platinum dish with water and some 
bromine, and kept ina warm place. The green solution obtained was filtered and 
evaporated, and finally crystallized by allowing it to remain in a bell-jar standing 
over sulphuric acid. 
Well-formed green crystals were obtained which, while they were very deli- 
quescent in the air, rapidly effloresced over sulphuric acid. In this respect they 
resemble cupric bromide. The only way they could be dried was by crushing 
rapidly between folds of blotting paper. The water of crystallization was esti- 
mated in the usual way by heating in the steam-oven and weighing at repeated 
intervals. The nickel was estimated by precipitating a solution boiled in a 
platinum dish with potassium hydroxide, and igniting the precipitate in a 
platinum crucible at a bright red-heat over a blow-pipe. ‘The bromine was, of 
course, determined gravimetrically as silver bromide. 
The composition of the salt is NiBr,°6H,O as the following figures show :-— 
Determination of the Water. 
I Te 
Salt taken for analysis, . . . EE OLOSIAS 273960 
Loss on heating to 100°C. till reelit constant, . 1:°2045 0°7957 
150) HER CBillin 6 5 0 oo BUNAY 33°21 
Determinations of Nickel and Bromine. 
Il II. Ill. 
Wreight ot/salt) taken) |) me ntcnn Ont o-e 0°8727 1:2382 
Weight of NiO precipitated, . . . . 01042 0-1990 — 
Nipercent; << - 5 a a 0 SRR 192 — 
Weight of AgBr pr ooibatedl ides he Fe _ -— 1:41438 
WYRE SGI, 5 of 6 ao 9 0 © 0 — — 0°6019 
== —- 48:61 
Br per cent., 
* Ann. Chim. Phys, vol. 44, p. 389. Pogg. Annalen, vol. 55, p.243. {Jour, Chem. Soc., vol. 12, 1874. 
