432 
POPULAR SCIENCE REVIEW. 
0-17 c.c. peroxide in 1,000 cubic metres. In dew artificially deposited in a 
badly ventilated room there was no peroxide ; its presence, however, became 
manifest as soon as the windows were thrown open. Dew and hoar frost 
deposited during the last horns of the night appeared to be pure water ; in 
dew collected during the evening hours peroxide was met with, the amount 
being 0*05 gramme to the litre. The peroxide is present in fog, and is appa- 
rently more abundant in spring than in autumn. The amount of peroxide 
present in any atmospheric deposit varies with the altitude at which that 
deposit has been formed ; the greater the altitude at which the condensation 
takes place, the greater is the quantity of peroxide which it will contain. 
This is doubtless due to the decomposition which that substance must 
undergo when exposed to organic vapours rising from the earth’s surface. 
In the air itself there is but little peroxide, the maximum quantity observed 
being 14 c.c. in 1,000 cubic metres of air. The author points out the scien- 
tific advantages which would attend systematic observation in this field at 
our meteorological stations. 
Cast Manganese. — Jordan has presented to the Academy of Sciences of 
Paris a specimen of fused manganese, obtained by smelting manganese ores 
in the blast furnace. About 10 per cent, of the metal is lost during the 
operation, and it seems not improbable that the metal is volatile at higher 
temperatures. The manganese appears to be very stable, the specimen above 
referred to having undergone no perceptible change in six months. It 
consists of 
Manganese . 
. , 
. 84-960 
Iron . 
. . 
. 8-550 
Carbon 
. . 
. 5-700 
Silicium 
. . 
. 0-660 
Sulphur 
. 
. 0-035 
Phosphorus . 
• • 
. 0-005 
99-910 
In one specimen the percentage amounted to 87‘4. — C'ompt. rend. 1878, 
No. 22. 
Expansion of Bismuth. — Marx directs attention to an experiment which 
admirably illustrates the force with which a metal like bismuth expands 
during the act of solidifying. He dips a long and narrow glass tube into 
the melted metal, and sucks it up the tube to a height of eight or ten inches. 
On allowing it to cool, the tube is shattered, often with explosive violence. 
The tube cracks along its length, and is broken up into long parallel glass 
rods or threads, which it would be difficult to produce by any other means. — 
Pol. Notizblatt, xxxiii. 44. 
Absorption of Carbonic Oxide by the Blood. — Grehart’s experiments on 
this subject have led him to the conclusion that if a man or animal be placed 
for half an hour in an atmosphere containing l-779th of carbonic oxide, 
one half of the red corpuscles will have taken up sufficient of the gas to 
render them unable to absorb oxygen ; by exposure to an atmosphere con- 
taining 1-1 449th of carbonic oxide, about one-fourth of the red corpuscles 
are rendered inactive. — Compt. rend., 1878, lxxxvi. 895. 
Alum and Dysentery. — Dounon’s observations go to show that dysentery 
