Variations of the Barometer under the Tropics. 831 
TEMPERATE ZONE. 
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PLACES OF OBSERVATION. 
inima of 
Night. 
inima of 
Morning 
o .■ 
03 J? 
so 
% 
axima of 
Evening 
ean exten 
Osciilatio: 
n lOOths 
i millim. 
OBSERVERS. 
s 
s 
s 
S. 
% 
Las Palmas (Great Canary), Lat } 
10 h 
4 h 
ll h 
1.10 h 
De Buch. 
28° 8' N. - J 
Coutelle. 
Cairo, Lat. 30° 3'. 
5 h 
10 
5 
10* 
1.75 
Toulouse, Lat. 43° 34' (mean of 5 ) 
5 H 
11 
1.20 
f Marque 
years), f 
10 
2 i ) 
\ Yicttor. 
Chambery, Lat. 45° 34V Height 1 
n 
».i 
1.00 
Billiet. 
13 toises, - ) 
10 
2 s 
Clermont-Ferrand, Lat. 45° 46'. [ 
8 
4 
10) 
0.94 
Ramond. 
Height 210 toises, - ) 
9 
3 
9J 
Strasburg, Lat. 48° 34', (mean of) 
6 years,) j 
5 
8* 
3| 
i 0.80 
j Herren. 
( Schneider. 
Paris, Lat. 48° 50', (mean of 9 years), 
9 
3 
0.72 
Arago. 
La Chapelle, near Dieppe, Lat. 49° 8 
55', - - - j 
9 
3 
0.36 
j Nell de 
( Breautte 
Konigsberg, Lat. 54° 42', (mean of) 
8 years, j 
8i 
2 I 
10 
0.20 
j Sommer & 
( Bessel. 
Art. XVIII . — Experiments on the Action of ' Water upon Glass , 
with some Observations on its slow Decomposition . By Mr 
T. Griffiths, Chemical Assistant in the Laboratory of the 
Royal Institution *. 
It is a commonly received notion that glass is capable of re- 
sisting, to a very great extent, the attacks of active chemical 
solvents, and that its alkali can neither be readily separated nor 
exhibited in an insulated form, without regularly submitting it 
to powerful decomposing agents. Speaking of glass, in common 
language, without any reference to the many soluble compounds 
so designated, it may be a new fact in chemistry to prove that 
this singular substance possesses highly alkaline properties, 
which may easily be shewn by the usual tests. 
Upon reducing some thick flint-glass to a moderately fine 
powder in an earthenware mortar, for the purpose of analysis, a 
portion of it was placed on turmeric paper, with the view of de- 
termining if it possessed any sensible alkaline property ; and, 
upon being moistened with water, the yellow colour of the test- 
* Journal of the Royal Institution, 
3 
