ON EUDIOMETERS. 297 



chouc ball filled with water. By squeezing the ball the 

 pipette is filled with water, and by allowing the water to 

 return into the ball the gas is sucked in. After measurement 

 the gas is forced into a flask surmounted with a graduated 

 tube and filled with an alkaline solution of pyrogallic acid. 

 The level of the liquid in the measuring tube and another 

 parallel to it is adjusted by a bottle and caoutchouc ball. 



Then there are three pieces of apparatus by Orsat, which 

 are very ingenious indeed, and w T hich all seem to be on the 

 same principle. In Orsat's apparatus the gas is measured 

 in a graduated tube connected by caoutchouc with a 

 reservoir of water, mercury, or dilute glycerine. By means 

 of a tube with several branches the gas may be passed into 

 bell-jars containing the different reagents for the absorption 

 of carbonic anhydride, a vessel containing a solution of 

 caustic potash and a number of glass tubes open at both 

 ends is employed. The tubes becoming moistened increase 

 the surface. Oxygen and carbonic oxide may be absorbed 

 by an ammoniacal solution in a bell jar containing copper- 

 wire, gauze, or the oxygen may first be absorbed by an 

 alkaline pyrogallate, and the carbonic oxide by the cuprous 

 solution. Between each absorption the gas is transferred 

 to the graduated tube and measured. 



Here is another ingenious apparatus by which eudio- 

 metric work can be performed. Here is a small hydrogen 

 apparatus by which hydrogen can be generated, passed into 

 it and measured. Instead of producing explosion, which 

 would destroy the instrument, the gas is slowly passed 

 through a small spiral of platinum heated by a flame, and 

 after having passed that it is transferred into a receptacle, 

 once more brought back into the measuring tube and the 

 diminution of volume measured. 



Lastly, there is one other apparatus which I cannot pass 

 over because it is entirely new and it appears to me to be 

 capable of considerable improvement. It is an apparatus 

 by Kiidorff. It is intended for the determination of 

 carbonic anhydride in coal gas. It is a Woulfe's bottle 

 with three stop-cocks ground in the necks, one being a 

 three-way-cock. The three-way-cock is turned so as to 

 connect one tube with the Woulfe's bottle, and a stream 

 of coal gas is driven through from an inlet tube until 

 you are quite sure that the whole of the air is expelled. 



