SCIENTIFIC SUMMARY. 
101 
320 grammes of ammonium nitrate gave 67*14 litres of nitrogen, at the 
normal temperature and pressure. In one experiment where 3 grammes of 
nitrate were heated with the requisite amount of manganese peroxide in a 
mercury hath at 205° 0., they yielded 606 cub. cent, of nitrogen ; the theoretical 
amount is 630 cub. cent. At higher temperatures than 215° 0. the reaction 
appears to be a complex one, the manganese nitrate being broken up into 
manganese oxide, hyponitric acid, and oxygen. 
The Estimation of Nickel. — A paper on this process, written by Margaret 
S. Cheney, and Ellen Swallow Richards, and dated from the 11 Women’s 
Laboratory, Massachusetts’ Institute of Technology,” appears in the 
“ Amer. Journ. Sci.,” 1877, xiv. p. 178. The authors having occasion to 
determine quantitatively the amount of nickel in some pyrrhotites and 
matts were led to examine the accuracy of the various methods proposed 
for the separation of that metal from iron. They found that which is 
known as the acetate process to be a tedious one, and the plan for the 
removal of the iron with ammonium hydrate very unsatisfactory : but good 
results were obtained by the process proposed by Field in 1859, who em- 
ployed lead oxide to effect the complete separation of the metals. In the 
case of the nickel, which they weighed as oxide, the analytical numbers 
were too high — a result which was to be expected •, and they were finally 
led to adopt a process based on the fact that nickel phosphate is completely 
soluble, while iron phosphate is almost insoluble, in acetic acid, in presence 
of an excess of sodium phosphate. After the metals which are thrown 
down by sulphuretted hydrogen have been removed, and the filtrate has been 
boiled to drive off the excess of that reagent, the iron is oxidized with nitric 
acid, and ammonium hydrate is added until a permanent precipitate begins 
to form, but not until complete precipitation of the iron oxide is effected. 
Acetic acid is then added to re-dissolve the oxide, and the deep-red coloured 
solution raised to the boiling point. An excess of ordinary sodium phos- 
phate is then added to it, and the nearly white precipitate is filtered off 
and washed with hot water containing acetic acid. The filtrate is heated 
nearly to the boiling point, and caustic potash is added to it till the odour 
of ammonia is distinctly perceptible. The apple-green precipitate of nickel 
phosphate is partially washed, dissolved in a little dilute sulphuric acid, the 
solution rendered strongly alkaline with ammonium hydrate, and the nickel 
precipitated with the battery ; a current from two quart cells charged with 
bichromate and sulphuric acid sufficed in two hours to completely precipitate 
the metal. The numbers fall only a little short of those required by theory, 
amounting in three experimental determinations to 99*06, 99*33, and 99*73 
per cent, respectively. 
Absorption of Carbonic Oxide. — Bottinger finds that carbonic oxide, when 
conducted through hydrocyanic acid cooled to a low temperature, is abun- 
dantly absorbed by that liquid ; if concentrated hydrochloric acid be added 
to the solution, the two liquids will not mix. When the vessel containing 
them is removed from the freezing mixture, a constant current of pure 
carbonic oxide is evolved ; on the subsequent application of heat the evolution 
of gas becomes stronger, while the gas itself is contaminated with hydro- 
cyanic acid ; finally the liquids mix and a turbulent disengagement of gas is 
the result, pure unaltered hydrocyanic acid remaining in the vessel. — JBei\ 
Deut. Chem. Gesell., 1877, x. 1122. 
