“ 
TRANSACTIONS OF THE SECTIONS. 37 
these lines of symmetry or interference varied in different years ; in the year 1842 the 
line of greatest symmetry passed from Dublin through Brussels to Munich; in 1845 
it appeared to be confined to the south of England. 
Mr. Birt next proceeded to notice the arrangements of the aérial currents or winds 
with regard to the distribution of pressure. He stated that the observations on the 
winds in November 1842, clearly established Prof. Dove’s theory of parallel and 
oppositely directed currents, and he showed by diagrams that if these currents are 
shifting ones, as the Professor suggests, as they passed over any tract of country in 
a direction transverse to those in which the wind was blowing in each, all the phe- 
nomena of an atmospheric wave would be produced. He remarked that if there was 
only one set of these parallel currents passing over a line of country, then the exa- 
mination of the phenomena of an atmospheric wave would be comparatively easy. 
The discussion of the observations had however shown that there were two sets of 
parallel and oppositely directed currents at right angles to each other, one set from 
the N.E. and 8.W., with a lateral motion from the N.W., and the other from N.W. 
and S.E., with a lateral motion from the S.W.; and also that when these currents are 
referred to the wave, the N.E. and N.W. currents, in their respective systems, re- 
present anterior slopes with the direction of the aérial currents at right angles to the 
axis of translation directed towards the left-hand; and the S.W. and S.E. currents 
represent posterior slopes, the direction of the aérial currents still at right angles to 
the axis of translation, but directed towards the right-hand*. ‘Vhe author considered 
that these rectangularly posited currents explained several phenomena, such as the 
barometric wind-rose, the revolution of the vane in one uniform direction, &c., and 
concluded his report with pointing out several important desiderata that it was desi- 
rable should be made the subjects of future inquiries. 
CHEMISTRY. 
On the Changes which Mercury sometimes suffers in Glass Vessels hermeti- 
cally sealed. By Prof. OrrstTep. 
Ir has been frequently noticed that. mercury inclosed in glass tubes, even when 
those tubes were hermetically sealed, undergoes a remarkable change. It first be- 
comes covered by a thin film of a yellow colour, which adheres to the glass, and 
becomes eventually nearly black. This has been attributed to oxidation, but the 
oxidation which would arise from the exceedingly small quantity of atmospheric air 
which could be contained within the bulbs exhibited by Professor Oersted was too 
small to account for the formation of such a quantity of dark and yellow powder as 
many of them exhibited. Professor Oersted referred the change on the mercury to 
the action of that metal on the glass of which the bulb was formed. It appears that 
sulphate of soda is frequently employed in the manufacture of glass, and it is thought 
that a sulphuret of mercury is formed by the decomposition of the glass itself. This 
is not however satisfactorily proved, and the subject has only been brought forward 
that attention might be directed to a subject which appeared to involve some remark- 
able conditions. 
On a second new Metal, Pelopium, contained in the Bavarian Tantalite. 
By Prof. H. Rose. 
In a former communication it had been shown that the so-called tantalic acid 
which occurs in the Bodenmais in Bavaria, consisted of two acids, one of which 
' differed materially from all known acids. To this Professor Rose gave the name of 
Niobium, regarding it as a new metallic oxide. After a most elaborate investigation, 
- Professor Rose has found that the other acid contains another oxide of a metal dif- 
* These directions are in close accordance with that of the rotation of the air in revolving 
_ Storms, and appear strongly to support Sir John Herschel’s suggestion, that such storms may 
_ be produced by the crossing of two large atmospheric waves moving in different directions. 
See Sir John’s Report on Meteorological Reductions, Report, 1843, p. 100. 
