IMPORTANCE OF RAIN. 289 



sent in the air through which it passes. Its 

 minute state of division, and the consequent 

 exposure of a vast amount of surface to the 

 soluble matters or gases present in the air, ren-' 

 ders it a most efficient and valuable medium for 

 bringing down the hoarded treasures of the air 

 to the needy and expectant soil. When the 

 chemist in his manipulations wishes to obtain a 

 saturated solution of a gas, he effects it by a 

 process as nearly as possible similar to that by 

 which in nature the same result is produced; 

 he violently agitates the liquid so as to reduce 

 it to a mass of drops, exposed on all sides to the 

 gas intended to be dissolved. Where machines 

 intended to charge water with gases, and partly 

 to dissolve the latter in the water, as in the 

 manufacture of soda water, are employed, the 

 same effect is produced by a revolving agitator 

 driven at such a speed as to beat the water into 

 a fine mist Now, M. Schubler has calculated 

 that upon a field of 26,910 square feet, the an- 

 nual fall of rain is about 2,520,000 Ibs. In this 

 large amount of rain-water is contained much 

 ammonia, on the lowest calculation about 80 Ibs. 

 All this ammonia existed previously in a gaseous 

 form in the air, having been brought down in a 

 dissolved state -by rain, and in this simple but 

 beautiful manner rendered valuable to vegeta- 

 tion ; to which, had it remained in the gaseous 



U 



