158 Progress of Invention. 



is added to it. Hence sodium amalgam is now an important article 

 of commerce. It is considered highly explosive, and therefore very 

 dangerous : hut such is not the case, the explosive property of pure 

 sodium on coming into contact with water is lost almost entirely 

 when it is associated with mercury, so as to form an amalgam. 

 But sodium amalgam is now likely to he superseded hy a far less 

 expensive, and it appears not less useful material. Caustic soda 

 has not only heen found quite as effective as sodium amalgam, hut 

 it is contested that the sodium in the amalgam actually assumes the 

 form of caustic soda hefore producing its effect. A very simple ex- 

 periment will show the efficiency of the soda. If a finely pulver- 

 ized metallic powder is thrown into water, no amount of stirring 

 will cause it to fall to the hottom of the vessel ; it is rendered 

 specifically lighter than the fluid by the coating of air which ad- 

 heres to it. But if a very small quantity of caustic soda or potash 

 is added it will soon descend from the surface to the hottom. It is 

 supposed that the minute particles of mercury also, and of gold, are 

 prevented from coming into contact hy a coating of air, which the 

 alkali removes in a way which has not yet been ascertained. This, 

 if the real, is perhaps not the only effect produced by the alkali. 

 The potash of soda must not be allowed to lose its causticity by ex- 

 posure to the air during transport, etc.", or it will be ineffective : it 

 may have become a carbonate, without those who use it being aware 

 of the fact. 



ISTew Application op Tuning-forks. — An instrument has recently 

 been constructed at Paris which possesses great power and sweet- 

 ness. It somewhat resembles a piano, but is far more simple, as 

 the strings are replaced by tuning-forks, one for each note. The 

 sounds are produced by hammers, and are very persistent unless 

 brought to an end by removing the fingers from the keys, and thus 

 allowing the dampers to act. 



Dissociation of Gases at High Temperatures. — Some interesting 

 researches on this subject have recently been made by M. L. Cail- 

 letet, in developing the discovery of M. Sainte-Claire Deville, that 

 at a high temperature the constituents contained in a mixture of 

 gases will separate. As it is necessary to cool the dissociated 

 elements rapidly, it was necessary to devise an apparatus suited to 

 the purpose. By means of this apparatus some important facts were 

 observed. Thus, that oxygen has no action whatever on hydrogen, 

 carbon, or carbonic oxide, placed within a mass which is at a tem- 

 perature higher than the melting point of platinum ; and the con- 

 clusion arrived at was that all bodies would most probably be dis- 

 sociated by a temperature sufficiently high. 



Application of a New Principle to Fire-arms. — The inertia of the 

 projectile causes a certain time to elapse before it is set in motion. A 

 certain amount, therefore, of the force of the gunpowder is wasted, 

 and the more rapid the explosion the greater the loss, from this 

 cause. M. Galant, of Liege, has invented a breech-loader which 

 meets this difficulty. The force of the charge is first communicated 

 to an elastic body which is easily set in motion, and the force which 

 in ordinary cases is wasted, but in this is stored up, is gradually 



