NATURAL PHILOSOPHY. 121 



consists of two metallic tubes, each closed at one end, and connecting to- 

 gether at the other, with a non-conducting ring of hard rubber, the inside 

 being lined with Iamb-skin. A hard rubber rod is placed within them, 

 the length of one of the tubes, and fitting them so as to move somewhat 

 freely from end to end. When the movable piece inside is allowed to 

 fall to one end, and the tube is raised to the connecting wire of the 

 burner, this piece changes its place again, tailing into the tube held by 

 the hand. The spark leaves the upper end of the tube at the same time 

 and lights the gas. 



The Table LigJd Burner consists of the same instrument, arranged 

 upon a pivot regularly attached to the pillar light. Am. Gas Light 



Journal. 







ELECTRICAL PROPERTIES OF PYROXILINE-PAPER AND GUN- 

 COTTON. 



Prof. Johnston, of the Wesleyan University, Middletown, Conn., in a 

 recent note to the editors of Sillimari's Journal, calhs attention to a 

 remarkable power in pyroxiline-paper of producing positive electrical ex- 

 citement in sulphur, sealing-wax, c. His note is as follows : "We are 

 told by writers on electricity that sulphur by friction with all other sub- 

 stances becomes negatively excited ; as cat's fur, on the other extreme, 

 by friction with all other substances becomes excited positively. But a 

 few days ago I made the discovery that sulphur by friction with paper- 

 pyroxiline (I will call it) is excited with positive electricity, as are also 

 sealing-wax, amber, &c. The paper is prepared in the same manner as 

 gun-cotton, which would also in all probability be found to possess the 

 same property." 



Prof. Sillimm farther adds, in relation to this topic: " I have repeated 

 and confirmed Prof. Johnston's experiment, extending it to gun-cotton. 

 I find as he suggests that the latter substance produces the same excite- 

 ment of positive electricity which is produced by the pyroxiline-paper. 

 The most energetic effects are produced when vulcanized india-rubber is 

 the electric. The opposite effects in this substance produced by flannel 

 and the gun-cotton or pyroxiline-paper are very striking, and will form a 

 good lecture-room illustration. These substances also produce powerful 

 positive excitement- in gliss. It is difficult from the use of pith balls 

 alone to determine which produces the most powerful positive excite- 

 ment, glass or hard rubber, when excited by gun-cotton or pyroxiline- 

 paper. This seeming anomaly, confounding our ordinary means of dis- 

 crimination in cases of electrical excitement demands further investiga- 

 tion. It would appear thaf. of negative electrics yet observed, these 

 azotized species of cellulose are the most remarkable, in comparison with 

 which the most highly negative electrics hitherto known become posi- 

 tive." 



NEW FORM OF ELECTRIC LIGHT. 



Prof. Seely, of New York, has recently obtained a patent for an 

 electric light, which is claimed to be more economical and effective 

 than any of the methods hitherto devised. He employs the current 

 generated by an ordinary f'rictional electrical machine, and obtains the 

 light by interrupting the current. It has long been known that a very 

 brilliant and steady light might be procured in this way, but the ob- 

 jection to its use is the uncertainty in the action of the frictional 

 11 



