INFLUENCE OF NITRATES. 103 



tity of the same soil contained only 13 grams of nitre. The 

 greater part had been dissolved out of the superficial soil. 



Some specimens of forest-soil, in a state of nature, fur- 

 nished no indication of nitrates ; others gave 0.7 and 3.27 

 grams of nitre to the cubic metre. 



The soil of meadows and pastures afforded from 1 to 11 

 grams of nitre to the cubic metre. Nineteen specimens of 

 good cultivated land gave, four of them none ; others from 

 0.8 to 1.33 ; the richer ones from 10.4 to 14.4, and one 

 fallow, of exceptional richness, as much as 108 grams of nitre 

 to the cubic metre. To the latter much calcareous matter 

 has been added. 



The soil of the conservatory, from which the nitrates would 

 not be washed away by rains, contained 89, or 161, and some 

 rather deep soil 185 grams of nitre to the cubic metre. 



The sources of the nitre are not difficult to understand 

 when we reflect that a manured soil, especially a calcareous 

 one, is just in the condition of an artificial nitre-bed. The 

 ultimate result of the decomposition of ordinary manure is a 

 residuum of alkaline and earthy salts, phosphates, and ni- 

 trates, the latter, with the ammonia furnishing the assimi- 

 lable nitrogen, all-essential to productive vegetation. In in- 

 corporating with the soil undecomposed manure, instead of 

 the ultimate results of decomposition, less loss is suffered from 

 prolonged rains wasting out the formed nitrates. 



The soluble matters washed out of the soil are to be sought 

 in the water. River and spring waters therefore act as manure 

 by the silex and alkali, the organic matter, and the nitrates 

 which they hold. The spring waters, poorest in nitre of 

 those examined, contained from 0,03 to 0.14 milligrams of 

 nitre to the litre ; the richer ones from 11 to 14 grams in 

 the cubic metre. 



As to the river- water, the Vesle in Champagne held 12 

 grams, the Seine at Paris 9 grams the cubic metre. These 

 were the richest. The Seine at Paris carries to the sea, in 

 times of low water, 58,000 kilograms, in times of high water, 

 194,000 kilograms, of nitre every twenty-four hours. What 

 enormous amounts of nitre must be carried into the sea by the 



