336 GRAPE CULTURE AND WINE-IMAKING. 



be equal to that in tbe bottles. The gas is prepared in tbe follow- 

 ing manner (see Fig. 46) : 



The cask A is filled witb chalk or carbonate of lime (limestone) 

 and water. The opening C is then closed hermetically, and sul- 

 phuric acid when chalk, chloric acid when limestone is used, is 

 poured through the leaden funnel B into the cask. The carbonic 

 acid thus developed is conducted through the pipe D into a small- 

 er cask filled with water, marked E, and from there through an- 

 other pipe, F, into the glass stand G, filled with small pieces of 

 chalk, which hind the last particles of free acids. Through the 

 pipe X the pure gas is led into the gasometer G {Fig. 45). This 

 is a bell-shaped vessel, of tin or tinned copper, which hangs in a 

 vat of the same metal, marked M F, filled with water up to two 

 inches from its margin, and is balanced by the weight V. By 

 turning the stopcock d the gas is conducted into the gasometer, 

 flows through d' into the forcing-pumj) P, while by a third stop- 

 cock, marked d'\ the gas returning from the vessel S is admitted 

 again into the gasometer. The pipes which connect the different 

 cocks are made of India-rubber. The pressure of the gas is meas- 

 ured by a small Manometer, marked m. 



By means of the forcing-pumj) P the gas is driven into the con- 

 denser A! through the pipe i. This is a copper cylinder plated 

 with tin, and holds 1|- hectolitres, the sides being from 3 to 4 mil- 

 limeters thick, in order to have sufficient strength to sustain a 

 pressure of 20 atmospheres, which is the amount of gas required 

 for one day's work. The condenser rests on a board, marked//', 

 and is fastened to the wall by means of an iron ring g g^ wound 

 round with rope, and is furnished with a stopcock, marked r'\ 

 which serves to let off the water that gathers in the cylinder. 

 The atmospheric pressure is measured by the Manometer M. 



Through the pipe i' t" r' the carbonic acid is let into the vessel 

 S, and the pressure regulated in the following manner : The pipe 

 v' v" conducts the gas into a cylinder of India-rubber one centi- 

 meter thick, which is closed by two round pieces of the same ma- 

 terial, fastened to bronze plates, one of which is fixed, while the 

 other is movable, and is pressed down by the gas putting in mo- 

 tion the pieces z and y, the teeth of the latter piece, turning the 

 wheel, gradually closing the cock r\ through which the gas is let 

 into the vessel S. 



By the elasticity of the India-rubber and a spiral wire which is 

 wound round the cylinder, the plate is drawn back, and so the 

 stopcock opened again ; and by this alternate opening and closing 

 of the entrance to the vessel S, the pressure is regulated. To still 

 increase the power of the regulator, a spring, Z, is attached to the 

 movable bronze plate. 



The VcsspX S (Fig. 45). — By pressing down the treadle ^?, the 

 piece/ which is furnished with a spring, is pulled down, which 

 moves the ring A, to which the piece lo is attached, so lowering 



