50 Transactions of the 



On the table before us are various foims of matter— metals, gases, 

 ete., but the atoms are mute, motionless as puppets, until the show- 

 man pulls the wire and sets them in motion. Under the influeuce of 

 electricity, the particles of attenuated gas, in the glass tubes, will be 

 seen to arrange themselves in the most beautiful order. Other foiTas, 

 or modes of force, will be called into being, 'i he chemical action in 

 the Voltaic battery (the action of the oxygen of sulphuric acid on tlie 

 zinc), generates the electricity ; this is convertible into magnetism, 

 motion, heat, and light : these forces being correlative, and, like 

 matter, absolutely indestructible. 



• ««*•«« 



A large induction coil was here introduced, and its construction 

 briefly explained. The coil, made by RuhmkorfF, of Paris, gives a 

 spark in air eight or nine inches long. The secondary wire is about 

 twenty-four miles in length. 



A number of vacuum tubes, as they are usually called, were then 

 exhibited. They are glass tubes, containing rarefied gases— hydrogen, 

 nitrogen, carbonic-acid gas, etc. Platinum wires are fused into the 

 ends of the tubes, the electric discharge taking place between the 

 wires. 



Each gas has its own colour. That of nitrogen is a lovely rose, 

 and it is doubtless to this gas, that the rose colour of the aurora 

 borealis is due. Carbonic-acid gas gives a beautiful white light, and 

 is remarkably liuninous. The stratification in the tubes containing 

 hydi-ogen gas is exceedingly beautiful. When examined by the 

 spectroscope, the characteristic bands of each gas are easily dis- 

 tinguished. 



The character of the discharge varies with the vacuum. As the 

 vacuum becomes nearly perfect, tlie discharge ceases to pass. It thus 

 appears that the presence of material particles is essential to the 

 communication of the electric force. 



'1 he fluorescence of uranium and of sulphate of quinine, under the 

 influence of the electric light, was beautifully shewn : some of the 

 vacuum tubes containing solutions of these substances. So also was 

 the phos]5horescence of sulphuret of calcium, the salt remaining dis- 

 tinctly luminous some time after the spark ceased to pass. 



Several tubes were caused to rotate rapidly, one experiment proving 

 the iniermittent character of the spark, and illustrating at the same 

 time persistence of vision. A single tube, in rapid rotation, illumin- 

 ated momentarily in several positions, within the eighth of a second, 

 presented the appearance of several tubes, thus forming a most 

 beautiful star of light. 



The persistence of -sision was also illustrated by the following 

 experiment : — a series of four Leyden jars, connected with each other, 

 Avere charged and dischaiged, almost simultaneously, with a detonating 

 sound. The spark momentarily illuminating a disc, with devices, which 

 was being ra])idly rotated ; the devices appeared with perfect distinct- 

 ness, just as they would if the disc had been motionless. 



In conclusion, ^Ir. Fry spoke of the value ot scientific discovery in 

 connection with the progress and extension of civilization. He 



