IV. LABORATOBY APPARATUS. 633 



through the pipe C, when hydrogen is at once produced. If no gas is taken 

 away the acid liquid is all forced back into the upper vessel, when the produc- 

 tion ceases. When gas is taken away at F the lessened resistance allows as 

 much acid to return to the lower vessel as will supply the demand. The foun- 

 tain head pressure is determined by the distance between the upper and lower 

 vessels, combined with the quantity of liquid in the upper chamber. The 

 burning pressure is determined by the weight M on the lever L, which when 

 once fixed remains constant and is independent of changes produced by the 

 rising and falling of the liquid in the pipe C. 



D is a perforated fence to prevent the zinc closing the bottom of tube C 

 F the tube through which the gas passes to the burner. G the stop-cock to 

 withdraw spent acid. H the stop-cock crank, at an angle of 45 when open. 

 I where the gas enters the bellows of the regulator. J bellows. K stud. L 

 lever. M weight. N connecting rod. O screw couplings. P supports. 



2572. Collection of Gas Lamps of novel Construction. 



(1.) Gas lamp provided with one regulator for air and gas. 



(2.) Gas lamp with separate regulator for air. 



(3.) Gas lamp with star support and chimney. 



(4.) Bunsen's gas lamp, single burner. 



(5.) Bunsen's gas lamp, with regulation for air supply. 



(6.) Bunsen's gas lamp, with star support and chimney. 



(7.) Bunsen's gas lamp, consisting of 3 burners. 



(8.) Bunsen's gas lamp, with regulation for air supply. 



(9.) Bunsen's gas lamp, consisting of 6 burners. 



(10.) Bunsen's gas lamp, provided with one regulator for both 

 gas and air. 



(11.) Hofmann's gas lamp. 



(12.) Hofmann's gas lamp, provided with an air regulator, star 

 support, and chimney. 



(13.) Hofmann's gas lamp, with a bent burner tube. 



(14.) Hofmaun's gas lamp, with a bent burner tube, and pro- 

 vided with an air regulator. 



(15.) Griffin's rose burner. 



(16.) Griffin's small gas lamp. 



(17.) Griffin's large gas lamp. 



(18.) Microchemical lamp. 



(19.) Iserlohn gas lamp, small size. 



(20.) Iserlohn gas lamp, middle size. 



(21.) Iserlohn gas lamp, larger size. 



(22.) A fusion gas lamp, consisting of 11 single burners, and 

 fixed on a stand. 



(23.) A gas lamp, consisting of 3 burners, each possessing a 

 separate regulator for a simultaneous supply of air and gas. 



(24.) A gas lamp, containing 4 burner tubes. 



Julius Schober, Berlin. 



2446. One-inch Solid Flame Bunsen Burner and two 

 Perforated Caps, the fine one for ordinary use, and the coarse 



