SCIENTIFIC SUMMARY. 
209 
is unable to form perchromic acid and does not reduce potassium permanga- 
nate. The author concludes his very interesting paper with some specula- 
tions on the relation of the oxides of sulphur to those of other non-metallic 
and of metallic elements, and promises to employ his method in the investi- 
tion of the higher oxides of other substances. — Compt. rend., lxxxvi. 20. 
The Crystallization of Lime , Strontia and Baryta. — Briigelmann describes 
the chemical and physical characters of these oxides when in a crystallized 
condition (“ Annalen der Chemie und Physik,” ii. 466). The crystals are 
formed when the nitrate of the metal, enclosed in a porcelain flask or retort, 
is submitted to the very high temperature of a furnace fed with coke. All 
three of the oxides form crystals, belonging to the regular system, and they 
are invariably found to be cubes ; in the case of lime, crystals having an 
edge one millimetre in length have been obtained. As a rule the residue 
left when a nitrate is treated in the manner described, has a vesicular or 
foliated appearance, and is apparently an amorphous mass ; a low power, 
however, is sufficient to show that it is made up of crystals. An examina- 
tion of crystals of each of these oxides in polarized light confirmed the 
observation that they all belong to the regular system. The lime produced 
from the nitrate is far less readily subject to change when exposed to the 
action of moisture or carbonic acid than that obtained by heating marble. 
These crystals (of lime) can be exposed to the air for many days without 
undergoing change, and to water or moisture for several hours before they fall 
to powder. That the materials in the hands of the author were pure 
oxides is proved by his analyses, which showed them to consist respectively 
of 99*64 per cent, of lime, 99*4 per cent, of strontia, and 99*32 per cent, of 
baryta. 
Separation of Nitrogen from Air. — Harcourt and Lupton have found 
(“ Ohem. Central-Blatt,” 1878, ii.) that in the removal of oxygen from air 
by passing it over red-hot copper turnings, a very large metallic surface 
must be exposed, since the reaction ceases win. the crust of oxide attains a 
certain thickness. The authors compass the difficulty by conducting the 
air through concentrated ammonia before it reaches the copper ; the oxide is 
in this way continually reduced. As long as the supply of ammonia is 
maintained a mixture of pure nitrogen and steam issues from the apparatus. 
Composition of the Smoke of Virginia Cigars. — Schwarz has examined these 
gases by the aid of Orsat’s apparatus, the use of which instrument he highly 
recommends for technical analysis. The products of the combustion of the 
tobacco were collected in an aspirator, and were found to contain 12*0 to 
12*85 per cent, carbonic acid, and 4*0 to 4*76 per cent, of carbonic oxide. 
The presence of the last-mentioned constituent explains the deleterious 
action of these cigars. — Chem. Central-Blatt. 1878, vii. 
Weights and Measures. — The German Federal Council issued, at the end 
of last year, a list of contractions which are to be employed in official 
documents to indicate the respective weights and measures, the names 
whereof are written beside them in the following table : 
Kilometer 
. . km 
Square kilometer 
. qkm 
Meter . 
. . m 
Hectar 
. ha 
Centimeter . 
. . cm 
Ar 
. a 
Millimeter 
. . mm 
Square meter 
. qm 
NEW SERIES, YOL. II. — NO. YI. P 
