80 On the Injiuence of the 



Diluted nitric acid, as it is highly probable that it is de- 

 composed in the organs of plaiits as in animal bodies, is 

 not only not pernicious, but advantageous *. 



The union of muriatic acid and of lime seems to be of 

 the same nature. Carbonic acid, with pure calcareous earth 

 forms common lime, which appears in nature as limestone 

 or as chalk. It is highly probable, and may be explained 

 from the laws of the athnilv of the nitrous and carbonic 

 acid for calcareous earth, tliat they unite alternately with 

 the latter — the carbonic acid in the night, and the nitrous 

 acid in the day. 



Tliis holds good only in the warm days of summer: in 

 the autunui and spring the nitrous acid which is formed 

 drives off the carbonic acid, as experience shows in salpetre' 

 manufactories. The phosphoric acid forms with it phos- 

 phorized calcareous earth. 



Burnt lime exercises on animal substances a corrosive 

 <]uality almost in the same manner as caustic alkali, from, 

 ■which the effect of lime to hasten the begun putrefaction of 

 oro-anized matters in a certain state of moisture may be 

 explained. Hence it is evident that lime always contributes 

 chemically to the nourishment of plants when it is not 

 an essential component part of them. And on the other 

 hand, that too long manuring with lime not mixed with 

 other kinds of manure, as attentive farmers have long 

 known from observation, destroys the good black mould, 

 and so far exhausts the soil : and hence the the proverb — 

 *< that it makes the children poor." 



Lime can be employed indefinitely only in clayey soil, 

 combined with sulphuric acid, sand, and phosphoric acid, 

 and also where there is a superabundance of black mould. 



Turf or peat land, therefore, may be brought to a state of 

 fertility by draining from it the water, and mixing with the 

 turf the requisite quantity of lime. 



I may mention, as a mechanical property of lime, that 

 it contributes to render clayey land tender, especially when 

 strewed over it, like marl, in combination with sand. 



4th, Magnesia, — This earth is very often a component 



And saltpen t- : 



A70tc - - 0-64 



Oxvgen - - 0*36 



Gough, in his Experimiints on the Vegetation ot Seeds, mentioned, be- 

 fore Mr. Humboldt, that wet mud possesses in a very high degree the 

 property of attracting oxygen. 



* Four ounces of sahpetre dissolved in 48 pounds of water and poured 

 OD the roots of carnations, secures them against tlie rot, and has a bene- 

 ficial influence on the coloui of the flowers. 



part 



