NEGEETTI AND ZAMBRA, HOLBOEN VIADUCT, E.G., 



FIG 2737. 



2742 Gassiot's Vacuum Tubes, of numerous shapes, for exhibiting the interesting- 

 electric stratification and brilliant coloured light produced by the passage 

 of electricity through rarefied air, gases, &c. The metal terminals of these 

 tubes are formed of Platinum or Aluminium wires. Price various 25s., 26s, 



Each. 

 s. d. 



Each. 

 s. d. 



2743 Carbonic Acid Vacuum Tube, with stick of Caustic 



Potash at one end .150 1100 



2744 Carbonic Acid Vacuum Tube, with Carbon Terminals 150 



2745 Geissler's Vacuum Tubes, for Spectrum Analysis, hermetically sealed. All of 



these tubes have been filled with different gases, such as Hydrogen, 

 Nitrogen, Oxygen, Carbonic Acid, Phosphoric Acid, Iodine, Bromine, 

 Cyanogen, Hydrochloric Acid, Nitrogen Protoxide, .Sulphuretted 

 Hydrogen, &c., and then exhausted as perfectly as is possible, 4s. 6d. each. 



Vacuum Tube, A (fig. 2745) 160 



Ditto D . . 15 



Ditto E . . 1 10 



Ditto F 1 10 



Vacuum Tube, G 



Ditto H 



Single Garland Tube, B 



Double ditto 



C 



1 10 

 1 5 



1 10 



2 



2746 Vacuum Tubes, for exhibiting illuminated names or 



mottoes according to size and design, made to order . 



2747 Large-Sized Vacuum Tube, with the words, 



" God save the Queen " 



2748 Ditto ditto smaller 



2749 Diadem or Coronet Vacuum Tubes .... 



2750 Siemen's Ozone Tube and Stand 



2751 Apparatus for showing the Rotation of a Spark round 



an Electro Magnet 



2752 Gassiot's Cascade, large size 



Price various. 



5 5 



2 10 



3 10 

 1 5 



2 10 



3 10 



3 10 



