38 Accident from compression of the Air. 
A very singular and inexplicable fact is, that iron, tin, antimony 
and tellurium, will not, like other metals, decompose the peroxide of 
hydrogen. ‘The act appears still more obscure, when we consider, 
that the decomposition is effected by the protoxides of iron and tin. 
Perhaps those of antimony and tellurium would produce the same 
etfect. o 
The phenomena quoted above, are not explicable on any other 
known principles, than those which we have here adopted. Whether 
our readers will consider the rationale sufficiently free from hypoth- 
esis we cannot determine. To us, it has appeared more probable, 
at each revisal. 
Arr. If].— Compression of the Air.—An account of a remarkable ac- 
cident which occurred in a mine of Bovey coal, in consequence of 
__ the compression of the Air ; by the Inspector, Dr. Professor Nég- 
_ gerath. (Jahrbuch der Chem. und Phys.) 
(Translated and communicated for this Journal.) 
Iv order to understand correctly, the following account of the ac- 
cident which occurred at the pit of Turnick in the territory of Co- 
logne, it is necessary to premise a few words concerning the subter- 
raneous position of the coal pits, and the manner of working them, 
which for some time has prevailed in this region. The coal business 
is of great importance in this district, and several hundred workmen 
are employed in it. 
Some pretty high ridges of hills, which arise in the basaltic Godes- 
berg, extend more than half a league from Bonn on the Rhine, to 
the region of Bergheim on the road from Cologne towards Aachen, 
where they end in a plain, constituting the main locality of the terna- 
ty formation of Bovey coal. This coal is commonly covered with 
layers of clay not very compact ; and over the clay to the surface of 
the ground, is a deposit of coarse sand and rubbish washed from the 
hills. Where this covering is thick and strong, in order to obtain 
the coal to advantage, the mining is performed by a process, or rather 
a particular kind of excavation, which in our region is termed twm- 
melbau.* The parts of the tummelbau are shafis, passages, and 
lbau is an excavation in the 
: In the Jahrbuch there is a plate, conveying a very clear 
idea of the manner of excavating these mines, 
