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POPULAR SCIENCE REVIEW. 
author, condemns decidedly the doctrine of emission as an explanation of the 
movement of the radiometer. 
Experiments with Frozen Dynamite . — Some interesting experiments were 
recently made at the works of the British Dynamite Company, at Stevenston, 
Ayrshire, with the view of proving that dynamite in a frozen state is as safe 
to handle and to transport as in an unfrozen state. They are reported in the 
11 Chemical News,” July 14. Professors James Thomson and Bottomley, of 
the University of Glasgow, were present. In the first experiment, several 
cartridges in a frozen state, and in some parts beginning to thaw, were thrown 
one by one from the hand, with great force, against an iron plate, without 
explosion. In the second experiment, a block of iron, about 400 lbs. weight, 
was allowed to fall from a height of about 20 feet on a light wooden box 
containing 20 lbs. of dynamite cartridges in a frozen state, and with slight 
signs of incipient thawing in spots more exposed to the warmth of the air. 
The box was smashed, and the cartridges were crushed flat and pounded 
together, but there was no explosion. The crushed cartridges were next 
made up into two heaps to be exploded. The ordinary detonator shatters, 
but does not explode the frozen dynamite. The explosion was therefore 
effected by inserting in each heap a small unfrozen cartridge, with the 
ordinary detonator inserted into it, and then firing this off by a Beckford 
fuse. The two heaps were exploded successively, and it is worthy of remark 
that the explosion of the first, though very violent, did not set the other 
off. 
Sound Attractions . — A recent number of “ Silliman’s American Journal” — 
which, by the way, is remarkable for its admirable summary of Physical 
Science— gives the following account of M. Doorak’s recent inquiries. It 
says : — “ M. Doorak has examined the attractions and repulsions of small 
pendulums hung near sonorous bodies. A square of paper or a piece of cork 
is hung by a silken thread, and held near a wooden rod, vibrating slowly. 
Varying the positions of the pendulum, it is sometimes attracted and some- 
times repelled. These motions seem to be due to the air-currents approach- 
ing or receding from the rod, and the motions of the cork served to determine 
approximately the directions. These results were verified by the motions 
of a flame and the indications of a very sensitive water manometer. The air 
thrust aside by the vibrating rod escapes laterally, repelling light bodies. 
This is replaced by air forming counter-currents toward the rod, producing 
the effect of attraction. When the amplitude of the vibrations is small, the 
rod acts like the prongs of a tuning-fork, and attraction takes place in every 
direction. In front of the opening of a tube of Kundt, is placed a second 
open tube, giving the same sound as the first, and suspended by two threads. 
Making the first tube resound loudly, the second tube is strongly repelled. 
The same effect is obtained if the second tube gives one of the harmonies of 
the first. Placing two tubes facing each other opposite the tube of Kundt 
and perpendicular to its axis, they tend to approach each other. With a 
very sensitive manometer it appears that in a column of air in a state of 
permanent vibration, the air at the nodes has an excess of pressure. This 
accounts for the heaping up of water in the loops of a tube of Kundt. It 
is explained by admitting that the amplitude of the vibrations cannot be 
neglected compared with their length. It follows that there ought to be a 
