Chemistry and Physics. 221 



Mont Blanc- and at Ohamouny) was not sufficiently irreat to give 

 a <l >stin<- diit'erence in consumption of the humine matter. M. 

 Want! :, further put a candle to burn under an air pump n-ceiver, 

 with special apertures, ami with increasing rarefaction, the ilame 

 was seen to enlarge, and its lumu inish. At a 



pressure of 90 mm., the greatest rarefaction produced, the lumin- 

 ous power was quite gone, and the flame, which now assumed 

 three-fold size, appeared to consist of three parts, an inner bluish- 

 p'c-en cone with a violet -heath, and a weakly violet mantle. 

 The diminution of the luminous power in this' case M. Wartha 

 explains by the fact that under less pressure less oi the products 

 of combustion are separated in the form of soot.— Xatw>\ xv, 

 167. E . c. P. 



12. Large Induction Coil— Mr. Wm. Sromswooni-; has iiad 

 t] '' 1 ' largest induction-coil yet made, constructed, for him by Mr. 

 Apps. This coil, which is capable ..f giving sparks 42 inches'long, 

 h constructed as follows: It has two primaries, one used for long 

 ■1 has a core consisting of a bundle of iron wires_ '032 

 in. thick, forming a solid cvlinder 44 in. long, and 3-56-5 in. in 

 diameter. Its weight is 67 lbs. The copper wire of this primary 

 is t>60 yards long, -om> in. in diameter, has ;l conductivity of *93 

 and a total resistance of 2-3 ohms. It contains ],344 turns wound 

 singly in six layers, has a total len-th of 42 in. with an internal 

 «iameter of :)■-'» in. and an external diameter of 4-75 in. The 

 °tli_<-r primary, which is intended to b is. d with bit ries of less 

 resistance for short, thick sparks, or for spectroscopes, i- heavier 

 t! »-;i the other, the core weighing 92 lbs. and the wire 84 lbs. 

 The latter may be so connected as to be equivalent to a wire 

 of double or six times tbe cross-section of a single wire. The sec- 

 ondary coil consists of -jso miles of wire arranged in 341,850 

 turns, li torms ;1 cvlinder 37T> in. in length. 9-5 internal and 

 20 inches external diameter. The total resistance is 110,200 

 ohms. It is wound in four sections, the diameter of the wire m 



"0110. The increased section of the < 



:l(, '-nmulated chaise tl 



iat portion of the wire has to carry. The 

 •oved to be smaller than was anticipated. 



'• q-l.p-d p| 







results.' 1 



iv> 'sheets of tin-foil 18X8-2oln., separated 

 ' varnished paper, -0055 thick. \\ ltli 5 







so nk of >s inches wa- obtained, with 10, 



one of : . ;5 j. 



30 one of 37-5, and later, one, of 42 inches. 



As these sparks „-,.,-,. 



obtained without difficulty, it appears not 









than -it present a still longer spark might 



b, ..:„..,,, 



1,,'ion' is'su -h that 70 cells have been used 



'iirv. Wit 



h the 28-inch spark a block of flint-glass 



of extreme brilliancy 



