ON MINIMETRIG ANALYSIS. 



19§ 



emptied by pressure/ and allowed to fill itself again through 

 the bottle. The fresh air gives up most of its carbonic acid 

 in passing through the liquid ; but as a little remains un- 

 absorbed_, the bottle is well shaken, so that the liquid may 

 absorb all the carbonic acid. The operation is repeated 

 until the desired precipitate is obtained. The number of 

 ballfuls being counted, on referring to a Table such as 

 the following, the percentage of carbonic acid is at once 

 obtained : — 



With baryta- water. Air at o° C, and 760 millims. bar^ 



Number of 



Per cent, of 

 carbonic acid 



Actual amount 



strokes of the 



of carbonic acid 



finger-pump, 

 or number of 



indicated in 

 the air. 



in the air of 

 the ball, in 



ballfuls of air. 



cub. centims. 



I 



0-444 



0-2515 



z 



0-222 



0-1257 



3 



0-148 



0-0838 



4 



OIII' 



0-0629 



5 



0-088 



0-0503 



6 



0-074 



0-0419 



7 



0-063 



0-0359 



8 



0-055 



0-0314 



9 



0-049 



0-0279 



10 



0-044 



0-0251 



II 



0-040 



0-0229 



12 



0-037 



0-0209 



13 



0-034 



0-0193 



H 



0-032 



0-0180 



IS 



0-029 



0-0167 



This Table is constructed for a ball of 2 ounces capacity ; 

 but of course any size of ball may be used, and a table 

 constructed to suit it. For very bad air (above 0*07 per 

 cent.) it is found advisable to use a ball of half the size. 



We might call the apparatus a finger -pump, if no better 

 name is suggested. 



In using this ball it is well to observe the method by 

 which the points of the fingers press into the centre. If 

 this is followed, the whole of the air may practically be 

 driven out. The ball is thus divided into two parts : one 



