70 Scientific Intelligence, [jA?f<* 



descend to the bottom, it can pass no farther, and is preserved 

 from contamination by the sulphurous gas in the bottle B. Fur- 

 ther, after the orifice of tube F is exposed, the atmospheric air, 

 rushing in through G, arrests the further passage of the Hquid 

 of D. 



" When an absorption has thus taken place, by exciting a fresli 

 action in the retort, the gas accumulates in the receiver ; and 

 when sufficient to support a column of fluid of the height of one 

 leg of the tube E, the fluid in the receiver will be forced into 

 the bottle B again ; when the gas will follow and pass into C ; 

 when, acting on the surface of the liquid that may have come 

 over into it, it forces it back through H into and the process 

 of saturation will proceed as before. 



If a bent funnel is used, as I, the equilibrium is still sooner 

 restored, by tlie air passing through it at once into the retort. 



" In obtaining nitric acid, when the strong acid is desired to 

 be kept unmixed in the receiver, it will be advisable to place an 

 empty bottle between the receiver and bottle B ; connecting it 

 and the receiver as B and C ; and connecting B with it, as B is 

 above connected with the receiver. 



" Since writing the above 1 have tried the apparatus, I think 

 very fairly ; and find it answer all I could wish. Where, how- 

 ever, the extrication of gas is very sudden, and large in amount^ 

 it will be best to leave each alternate bottle empty. Thus : 



empty empty empty 



" The Gentleman who has improved this apparatus, as described 

 above, has, within a few days, suggested the plan of a self-re- 

 gistering contrivance to send over the acid which may be required 

 in the retort for the decomposition of the materials. This I 

 mean to try in a few days. The plan is simply thus : From the 

 tubular of the retort 

 goes a bent tube into a 

 bottle of [say] sulphuric 

 acid to tlie bottom. 

 When absorption of the 

 extricated gas, from the 

 materials in the retort, 

 takes place, the atmos- 

 pheric pressure will 

 force some acid up the 

 tube^ and it will pass into the retort j and this will occur as 



