ABSTRACTS OF TECHNICAL ARTICLES 599 



long periods. This apparatus has been utilized to calibrate a sensitive 

 humidity recorder capable of continuously recording atmospheric 

 humidities up to 2.9 per cent by volume of water vapor in air (equiva- 

 lent to about 95 per cent relative humidity at 25° C.) with a sensitivity 

 of 0.0016 per cent by volume (0.05 per cent relative humidity at 25° C). 

 The use of the recorder in connection with the constant humidity appa- 

 ratus is described and certain typical data illustrating the performance 

 are given. 



