ber abe 
ee Pe 
Mineralogy and Geology. — 413, 
part, above as well as below; the difference in proportion is but slight, 
and where appreciable, there is some reason to believe that the carbonic 
acid is in greater quantity in the upper parts of the room. These ex- 
periments establish the very important fact that all the air of a room 
must be changed in order to restore its purity. The plans sometimes 
resorted to, to draw off the air in the lower part of the room, or change 
this portion only by circulation, are wholly ineffectual as a means. of 
_ Yentilation. pi cit 
11. On the Products of the Oxydation of Gelatine by Chromic 
| ; Acid ; by Prof. Marcuanp, (Chem, Gaz., No. 77, p. 10.)—40 gram- 
mes of gelatine were dissolved ina mixture of 1000 grammes of water 
and 300 of sulphuric acid, and the solution, after cooling, was mixed 
with 160 grammes of bichromate of potash. On heating the mixture 
the odors of the oil of bitter almonds and hydrocyanic acid are evol- 
ved. The distillate was agitated with oxyd of mercury, when a con- 
siderable quantity of cyanid of mercury and some formiate was obtained. 
The liquid distilled off from an excess of oxyd of mercury, still retain- 
ed the odor of bitter almonds, which only disappeared after the addi- 
tion of caustic potash and prolonged exposure to the air. From the 
Solution a salt was obtained, soluble in alcohol, which gave with hydro- 
*hloric acid, crystals having all the characters of benzoic acid. These 
Teactions leave no doubt that hydruret of benzoyle is a product of the 
oxydation of gelatine. When the gelatine is in excess we obtain noth- 
ing but carbonic with pure formic acid. 
12. Colors of Quartz; by M. Hertz, (Poggend. Ann., |, 519.)— 
M. Heintz shows that the color of carnelian is not due to an organic 
Substance ; and that instead, it contains 0-05 per cent. of peroxyd of 
iron, He also states that the tint of amethyst is due toa compound of 
Peroxyd of iron and soda, and not to manganese. 
Il. Mrneratocy anp GEOLOGY. 
1, Stroganowite, a new mineral ; by M. Hermann, (Journ. d’Erdmann, 
XXxiv, 177.)—This mineral was found in Russia, in the bed of the river 
Sludanka, in crystalline masses of a clear green color and foliated tex- 
ture, cleaving also in two directions nearly at right angles. Specific 
Stavity 2:79; hardness, that of apatite ; lustre resinous; translucent or 
Semi-transparent. It has the composition of scapolite, along with a 
Portion of carbonate of lime, (a mixture ?) giving the formula Ca?Si-+- 
2Al Sit-Ca 6. ) 
oh: Xylite, a new mineral ; by M. Hermann, (Journ. d’Erdmann, xxxiv, 
ste -)—Xylite is from the copper mines of the Ural. It is essentially a 
ee si of ion ; it has a deep brown color, a fibrous fracture, specific 
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