436 NEGRETTI AND ZAMBRA, HOLBORN YIADUCT, B.C., 



Each. Each. 



s. (1. s. d. 



2572 Model Canon or Bomb, mounted on mahogany stand, 



with binding screws, &c., for firing Gunpowder by 



Galvanic Battery (fig. 2572) 110 



2573 Model Apparatus for Submarine Explosions. For 



explaining and exhibiting the method of firing gun- 

 powder or other explosive compounds (Torpedoes) 

 beneath the surface of water, or at long distances, 

 either for Engineering purposes, or for Naval and 

 Military warfare 0156 220 



2574 Rectangular Battery Cells, of hard glazed Porcelain, 



with porous jars, 6-in. high, G^-in. wide, 2-in. thick . 046 



2575 Ditto ditto 6-in. high, 4-in. wide, 2-in. thick . 036 



2576 Rectangular Battery Cells, 5-in. high, 3-in. wide, l-in. 



thick ....' 028 



2577 Glass Battery Cells, of various dimensions . from 46 



2578 Ebonite,ditto from 046 



2579 Gutta Percha ditto Acid Holders, various 



2580 Platinized Silver for Smee's Battery . . per oz. 12 6 



2581 Platinum Foil and Wire of all thicknesses, variable. 



About per dram 5s. per oz. 1 15 



2582 Amalgamated Zinc Plates, cut to various sizes, per Ib. 016 



2583 Zinc Rods for Daniell's Batteries, each 8d., or accord- 



ing to weight 010 014 



2584 Galvanic Conducting or Connecting Wires, in pairs, of 



convenient length for experimental or Medical use, 

 insulated with Cotton or Gutta Percha, various 

 lengths and sizes . . . ' . . from per pair 026 



2585 Boxwood Charcoal, for points . . . per oz. 006 



2586 Charcoal or Graphite Points, for Electric Light, per pair 010 



2587 Carbon or Graphite Battery Plates. 



Inches 4xl 6xli 6x2 6x3 8x4 12x4 



Price 9d. Is. Is. 4d. Is. 8d. 2s. 3s. 6d. 



2588 Gold, Silver, Platinum, Brass, Copper, Zinc, Iron,'and 



Steel Wire and Foil, for combustion, small reels .006 026 



2589 A Series of Six Smee's Batteries, in a tray ; apparatus for decomposing 



water into oxygen and hydrogen ; V tube for decomposing neutral salts, 

 various metal wires and foils for igniting and deflagrating, and a glass 

 trough fitted for depositing metals by the electrotype or electro-gilding 

 process. A small useful set for the use of Schoolmasters, for instructing a 

 class . 3 10 



2590 Larger Series, suited for Lecturers . . . .550 660 



The following values have been obtained for the Electro-Motive Force of the 

 most useful battery combinations; they are the mean values of many careful 

 determinations : 



Bunsen's Battery 839 



Grove's 829 



Smee's ' . . . . . . 210 



Wollaston's 208 



GANOT. 



