Art. XXI. — Description of Vacuum Apparatus. 

 By H. Sutton. 



(With Diagram.) 

 [Read 13th December, 1881.] 



This apparatus is the outcome of several forms of vacuum 

 apparatus I have devised for the rapid production of high 

 vacuum suitable for electric lighting by the incandescent 

 system, or investigations such as Mr. Crook es has recently 

 given to science. 



A mercury bottle (m) when held up, allows mercury to 

 rise in tube (A), filling reservoir (B), and rising in branch 

 pipe (C) isolates lamp globe (H) from reservoir (B). The 

 mercury passes by outlet pipe (D), filling vessel (G) till it 

 overflows by pipe (E) into vessel (F) ; (G) is a glass tube of 

 large diameter, having a glass stopper in each end, both 

 stoppers being covered by a mercury jacket ; the lower half 

 of this tube is filled with broken pumice, soaked in 

 sulphuric acid to absorb any moisture, the upper half 

 being filled with pumice, gilded with gold leaf to absorb 

 traces of mercury vapour. On lowering mercury bottle, 

 the mercury descends in reservoir (B) and pipe (C), 

 leaving a Torcillian vacuum in (B), the mercury in 

 (D) being supported by atmospheric pressure. On lowering 

 (m) sufficiently, communication is established between 

 reservoir (B) and vessel to be exhausted (H) by means of 

 branch pipe (C) and dissecting apparatus (G), the air in (H) 

 then expanding over into (B) ; the mercury bottle (m) is 

 then raised again, and the mercury rising in (B) drives out 

 the expanded air by outlet pipe (D). This pipe is bent back 

 on itself at the lower end ; this is to prevent the ingress of 

 any air that might collect on end of pipe in vessel (I), 

 alternate raising and lowering the mercury bottle (m) pro- 

 ducing a vacuum. 



