44 



THE ROYAL SOCIETY OF CANADA 



thermostat temperature and column 5, the ratio of the heUum to 

 hydrogen permeability from permeabilities calculated to two decimal 

 places. 



The mean value of the ratio from Table II is 0-66, from Table III 

 (omitting skin-lined fabrics) is 0-72. As the ratio with fabric 2 was 

 abnormal, additional tests are being carried out on this fabric to 

 ascertain the reason. For the two skin-lined fabrics the ratio is about 

 unity. Additional tests of higher accuracy are also being made on 

 these fabrics. Barr^ concludes that the ratio for gold beaters' skin is 

 about 1-5, with a footnote that this ratio may probably be more 

 nearly equal to unity. 



, Table II 



Interferometer Results 



' Barr. Loc. cit. 



