320 Messrs. Haldane and Pernbrey on an Improved Method 



in a wire sieve with about 12 meshes to the inch, and the 

 product freed from powder by a finer sieve. We have also 

 tried commercial soda-lime similarly sifted, and found that 

 it absorbed C0 2 well (see p. 321). As a precaution against 

 blocking of the tubing by soda-lime during the process of 

 fitting, a small plug may be placed in the end of the tube 

 and afterwards be withdrawn by a string attached to it. The 

 figure shows that a piece of cotton-wool is placed between 

 the surface of the soda-lime and the cork ; the object of this 

 is to prevent soda-lime being carried over in the form of 

 powder by a rapid air-current. 



The method was tested in the same way as that for mois- 

 ture. As regards accidental errors of weighing, what was 

 said above with regard to the apparatus for moisture applies 

 equally to that for carbonic acid. With respect to the efficiency 

 of the absorption, we may first quote the results of two 

 experiments in which the soda-lime and sulphuric-acid tubes 

 were weighed separately. In the subsequent experiments 

 the double absorption-tubes just described were employed. 



Experiment No. 1. 



The tubes were arranged in the following order; — 1 and 2, 

 sulphuric acid ; 3, soda-lime ; 4, sulphuric acid ; 5, soda- 

 lime ; 6, sulphuric acid. 90 litres aspirated at a rate of 

 1 litre per minute. 



Tube 3 



» ^ 

 „ 5 



+ 0-0463), ,, ^fwvoao 

 + 0*0405 f to g etner +0*0868. 



+ 0*0220 (together —0*0001. 



Repetition of No. 

 per minute. 



Tube 3 

 ,i ^ 

 ,i 5 

 „ 6 



Experiment No. 2. 

 1 ; 90 litres aspirated at a rate of 1 litre 



: : :SS} +0-H98. 



. . -0-0828 ■) Mr>An , 

 . . + 0-0832 j +0-0004. 



Experiment No. 3. 

 90 litres aspirated at a rate of 1 litre per minute. 



Soda-lime, pair 1 

 .. 2 



+ 0*1615. 

 + 0*0001. 



