268 Scientific Intelligence. 
ternal appearance chromium resembles iron, but resists better the ac- 
tion of moist air, and on heating in the air burns to sesquioxyd of chro- 
mium. Chlorhydric and sulphuric acid dissolve it with difficulty, form- 
ing protochlorid and sulphate of protoxyd of chromium. Nitric acid, 
ve oiling, scarcely attacks it: its density corresponds almost 
precinoly to that deduced from the — volume of the metals of the 
magnesia group. Ino xperi — reduction of the metal took 
as 0-067: w 
when there is an abundant production of a combination of the two 
oxyds of chromium as an almost black ——— powder. Chlorid of 
manganese is decomposed like chlorid of chromium ; the metallic man- 
ganese is obtained in large brittle leaves which oxydize in the air al- 
most as easily as potassium. Sa an amalgamated platinum wire'is 
covered with a gray layer of calcium which contains but little mercury. 
The reduction of calcium is however difficult; that of barium is much 
easier, and masses of amalgam weighing 1 gramme are easily 0 obtained. 
This amalgam is solid, silyer white, and very crystalline : heated ina 
current of hydro en it leaves a dark etn mass, in the cavities 
covere od with a Rabpbe a layer of lim hen melted ie is 
made to form the: negative pole, an alloy cooing from 8 to 12 pet 
cent. of calcium i is easily obtained. ‘he a r proposes to ee 
pri 
[Note-—The_ itvsttions German chemist does not/appear to have 
been acquainted with the experiments made in this country by Dr. Hare 
on the reduction of Barium, Strontium and Calcium “by the galvanic 
Pp rs reasonable to suppose that this ‘influence 's 
very powerful in the battery cells themselves, as well ‘as in -«§ 
posing cells. those batteries in which, like Grove’s and Daniell’s, 
two metals weit two liquids are employe a, and in which a red 
takes place at the surface of the negative metal, it would seem that such 
dimensions should be given to the surface of the negative — eo 
the electric density shall be exactly rane eu to produce the 
chemical effect required at that surface, whether reduction of cone 
or oxydation of hydrogen. The writer would furthermore sug: 9 
the explanation of the remarkable effects of polarization — produced y 
the magneto-electric machine and mentioned in the previous abstract, 
is to be found in the peculiar density of the magneto-electric current, 
under the circumstances mentioned, and not merely in its discontinuous 
