in Agriculture. 



183 



sodium, because, in addition to the trifling excess unavoidably 

 added in order to obtain the bhie tint on the litmus-paper (which 

 is so slight that it need not, and indeed could not, be regarded), 

 the water in which the salt is dissolved exercises a certain amount 

 of absorption : this is not, however, much ; the quantity of water 

 contained in the above 100 grains of saturated solution masking 

 •0046 of a grain of ammonia (NH'*0), which would make the 

 true amount absorbed by 100 grains of salt solution, '0237 of a 

 grain ; and that absorbed by 100 grains of solid salt, -0893 of a 

 grain. This, however, will not affect the subsequent experiments. 

 ■But the amount of ammonia absorbed by this constituent, 

 although really very considerable, and of great importance in an 

 agricultural point of view, did not yet correspond to the appa- 

 rent absorbing power possessed by the specimens of agricultiu'al 

 salt. The following comparative experiments w^ere therefore 

 made with the view of ascertaining the absolute amount of am- 

 monia which these samples absorbed. The solutions used for 

 these expei'iments were prepared by digesting great excess of 

 the salt with cold water for some time, so as to approximate 

 the manner of making the solution as closely as possible to that 

 which would occm- in nature. The experiments themselves were 

 varied by diluting both the ammonia and salt solutions, without 

 any very great difference of result. 



