On the Nitrates contained in the Soil and in Water. 499 



contained in the soil ; and that the favourable action exerted by 

 the nitrate, even from the beginning, is exerted even without the 

 presence of decaying organic substances. 



He found that plants developed under the influence of nitrate 

 of potash grew more rapidly, reached a greater height, weighed 

 more, and exhibited a greater absorption of nitrogen, than such 

 as grew without the addition of that salt. Similar conclusions 

 were obtained from experiments in which Boussingault grew 

 cress with and without the addition of nitrate of soda. 



He is of opinion that nitrates act upon vegetation as energeti- 

 cally as, and even more so than ammoniacal salts. He discusses 

 the question whether the nitrogen of the air, which has been 

 converted by ozonized oxygen into nitric acid, contributes to the 

 development of plants. 



More recently Boussingault has published an abstract* of 

 some researches on the quantity of nitrates contained in the soil 

 and in water. He found in some very highly manured soil from 

 a kitchen-garden, an amount of nitre corresponding to 1055 

 kilogrammes in a hectare. This immense quantity of nitre is 

 not surprising in a richly manured soil, for with the exception 

 of its not being protected against the rain, such a soil possesses 

 all the conditions of a nitre-bed. A portion of the same soil 

 examined after twenty days' continued rain, gave a quantity of 

 nitre corresponding to 43 kilogrammes per hectare. The large 

 quantity of nitre arises from the amount of manure which is added 

 to the soil. A series of analyses of soils from forest land, arable 

 land, and chalk and marl soils, gave quantities of nitre which, 

 although often small, were sufficient to show the frequency of 

 nitre in the vegetable kingdom, even in places where no other 

 manure than rain-water had been added. Soils taken from hot- 

 houses and greenhouses gave numbers showing a very large 

 amount of nitre. Boussingault examined also the water from 

 springs, from rivers and wells. In the wells of large towns he 

 found the largest quantities. Some wells in Paris contained 

 0-31 grm. in a litre, and he calculates that if this were used in 

 making bread, it would give to every kilogramme of bread 1 grm. 

 of nitrate of potash. 



He concludeb, that, with respect to the fertilizing principles 

 conveyed to the earth, the waters which circulate from the sur- 

 face or at a small depth act more by the nitre than by the am- 

 monia contained in them. In his memoir on the quantity of 

 ammonia contained in water, Boussingault showed that river- 

 water rarely contained more than 0-2 grm., and spring- water 

 0-02 grm. of amuionia in the cubic metre ; whereas the results 

 * Comptes Rendus, January 2i\, 1H57. 



