122 



PRaCEZDLN'GS OF THE AMERICAN ACADEMY . 



apparatus (Fig. 9), taken, like our other cuts, from the catalogue 

 of John Matthews. By pressing the foot on a pedal shown at the base 



Fio-. 7. 



Fis. «■ 



of the apparatus, the siphon — confined in a cage — is raised, so that 

 its mouth is forced tightly against one opening of a valve of peculiar 

 construction, the second opening of which is united by a block-tin tube 

 to a fountain ; while at the same time the handle of the siphon is 

 pressed back. On now pushing the upper lever shown in the cut to the 

 right, the valve of the fountain having been previously opened, a con- 

 nection is made between the fountain and the siphon ; when the charged 

 water rushes into the latter, condensing the air to a fraction of its origi- 

 Bal volume. If next the same lever is pushed momentarily to the left, 

 the first connection is closed; while a vent is opened, through which 

 the condensed air rushes out into the atmosphere before the gas in 

 solution has time to escape, and then on pushing back the handle a 

 further portion of liquid enters, nearly filling the interior of the bottle. 

 Lastly, on raising the foot, the valve of the siphon shuts at the same 

 time that the bottle is lowered and released from its cage, — the whole 

 process being the work of a few seconds. At the first filling, there 

 sometimes remains a small amount of air in the siphon, so that the 

 solution becomes slightly turbid on standing; but this effect of oxidation 

 can be easily avoided by using a sufficient amount of marble powder 



