1869.] Flujsics. 471 



will not only be valuable to Professor Pepper to illustrate the 

 wonders of electricity to the general public, but it has already been 

 placed by him at the disposal of Dr. Piichardson and other scien- 

 tific men as a means of promoting scientific research. 



Dr. Sarrazin has noticed some hitherto unknown phenomena of 

 phosphorescence. As soon as pure oxygen is reduced to a pressure 

 of only two millimetres or less, it becomes exceedingly luminous 

 under the influence of electricity. No other known gas is pos- 

 sessed of this property. All compound gases which contain oxygen 

 become also luminous, and most so the protoxide of nitrogen. 

 The doctor has found that the cause of this phosphorescence is due 

 to the formation of ozone, since it does not take place when, 

 previous to passing an electric current through the gas, powdered 

 metallic silver has been introduced into the space containing the 

 gas ; in this case the silver becomes rapidly oxidized. 



While engaged in studying the part which sulphuric acid plays 

 in these phenomena. Dr. Sarrazin found that when a small quantity 

 of this acid, which is considered non-volatile at ordinary tempe- 

 ratures, was confined along with nitrogen gas, for instance, in a 

 gas jar, and an electric current passed through, a very intense 

 luminosity was caused, notwithstanding nitrogen is not by itself 

 rendered luminous under these conditions. The author found that 

 there was decomposition of sulphuric acid, with formation of ozone, 

 and that the phenomena ceased when powdered silver was intro- 

 duced. 



Mr. Freidel has quite recently discovered that silicated hydrogen 

 gas is entirely decomposed by the electric spark, giving rise in the 

 eudiometer to a shower of amorphous silicium of a brown colour. 



A phono-electroscope has lately been described by Mr. Edwin 

 Smith, M.A., for the purpose of illustrating the heating power of 

 the voltaic current. It consists of a rectangular wooden box, 

 10 inches by 5, two steel or platinum wires stretched from end to 

 end, a small spindle carrying two quiU plectra, and an eccentric 

 wheel for making and breaking the current through one of the 

 wires. The wheel turns under a brass spring, which plays upon a 

 button. The spring is connected with one electrode of the battery, 

 the button with the wire nearest to it, and this wire with the other 

 electrode. To exhibit the use of the instrument : first, tighten the 

 wires by means of milled-headed screws, to unison, to about the 

 pitch of middle C ; then turn the spindle so as to sound the two 

 notes in succession before the eccentric wheel makes the circuit. 

 After these have unison, turn the spindle a little more ; the circuit 

 is made by wheel and spring, and presently the plectra are allowed 

 to play a second tinie on the wires, which now sound, with an interval 

 of a tone or more, according to the quantity of electricity which has 



