286 Mr. T. Tate's Experimental Researches on 



and ratio of maximum absorptions = —-=*78. Again, two 



equal surfaces of calico, but the one double the weight of the 

 other, absorbed during the same time of exposure to the air, 

 weights of moisture very nearly proportional to their respective 

 weights. 



2. The weights of moisture absorbed by an absorbent exposed 

 to a humid atmosphere in equal successive intervals of time are 

 (nearly) in geometrical progression. 



Thus, for example, during successive intervals of thirty minutes, 

 the weights of moisture absorbed by a piece of black cloth, pre- 

 senting a surface of 150 square inches to the air, were found to 

 be as follows : — 



Moisture absorbed, 

 in grains. 



During the 1st interval 17'4 



2nd „ 13-5 = 17-4 x } nearly. 



3rd „ 10-0= 17-4 x (f) 2 „ 

 4th „ 7-0 = 17-4 x (|) 3 „ 



Absorption of moisture by sulphuric acid from an atmosphere 

 saturated with the vapour of water. 



Equal measures of strong sulphuric acid diluted with different 

 proportions of water were introduced into a beaker 2| inches in 

 diameter, the liquid being half an inch from the edge of the glass ; 

 and the beaker with the acid was placed on a tray containing 

 water, and covered over with a large receiver about 1 foot in dia- 

 meter. The absorption by strong sulphuric acid, during twenty- 

 four hours, being first determined, the strong acid was succes- 

 sively diluted with four equivalents of water, and the weights of 

 moisture absorbed in twenty- four hours by the respective liquids 

 were determined as follows : — 





Corresponding weight 







of water absorbed in 



Value of a from 



Dilution of the acid. 



twenty-four hours, 



the formula 





in grains. 

 a. 



a=44'8X-6A\ 







448 



44-8 



4HO 



26-6 



26-8 



8HO 



16-0 



161 



12HO 



9-2 



9-6 



16HO 



6-0 



5-8 



where k = 



nKO 

 4HO" 



Here it will be observed that, whilst the 



dilution advances according to an arithmetical progression, the 



