4 BULLETIN 494, r. S. DEPARTMENT OF AGRICULTURE. 



water, and in this condition the water was drawn into the cloths by 

 capillarity almost to the top of the frames. Over the frames was 

 placed a galvanized-steel cover, or hood, open at one end and so ar- 

 ranged at the other end as to inclose a 16-inch electric fan. The cur- 

 rent of air from the fan was directed between and over the saturated 

 cloths. In this way the water was evaporated and given off to the 

 air in the room, increasing the relative humidity more efficiently 

 and safely than by any method previously tried. However, it was 

 soon found that the upper part of the cloths soon became dry under 

 the influence of the air current from the fan, and in an hour or so 

 the effectiveness of the apparatus became greatly diminished. 



An attempt was then made to find a cloth more absorptive than 

 the kinds first used. Many materials were tried, with the result 

 that it was decided to use Kussian crash, a very coarse linen cloth 

 that is used for making towels and for decorative purposes. 



With the use of the Russian crash cloths the efficiency of the 

 humidifier was improved, but it was still imperfect under very dry 

 atmospheric conditions. Various expedients were tried to increase 

 still further the evaporation of the water in the pan, such as by the 

 addition of filter paper, sponges, and other quickly absorptive 

 materials. 



THE INVENTION OF THE HUMIDIFIER. 



While working on this phase of the problem, the writer con- 

 structed a machine with two water pans, an upper and a lower one, 

 with strips of cloth extending through slots in the bottom of the 

 upper pan to the lower pan. It w T as thought that in this machine it 

 would be possible to control the flow of water from the upper pan 

 to the cloths through the slots by pressing the slots together by means 

 of thumbscrews. This method was found to be impracticable. It 

 was in this w T ork that the idea occurred of raising the sides of the 

 slots several inches, so that they protruded above the w r ater in the 

 top pan. The cloths were drawn up through the raised slots and the 

 edges were allowed to drop into the water to the bottom of the pan. 



Under these conditions, the water in the pan w T as raised on the 

 cloths by capillarity to the top of the raised slots, where it dropped 

 down through the suspended cloths by gravity and capillarity com- 

 bined. This arrangement proved to be successful in every respect 

 and met the requirements for use in lemon curing rooms very 

 satisfactorily. 



It was found that the rate of flow of water from the upper pan 

 through the cloths to the lower pan could be regulated to a nicety 

 by varying the height of the raised slots, thereby changing the length 

 of the cloth through which the water is drawn by capillarity. 



