96 CHEMICAL MANURES. 



To-day it is worth $8.55, but this price will certainly be lower in the 

 future. 



Nitrate of Soda. 



Nitrate of soda is formed from nitric acid and soda. Here is the 

 exact composition : 



Azotic acid 63. 58 



Soda 80.47 



100.00 



Nitric acid itself being formed of 



Azote 14 



Oxygen 40 



54 



it follows that the nitrate of soda contains 16.4 of azote when chem- 

 ically pure. That of commerce contains only 14 or 15 per cent. 

 Nitrate of soda is found in Peru, where it exists in the form of com- 

 pact conglomerates, mixed with sand and marine salt. 



The earthquakes on the Peruvian coast this year have affected the 

 importation of this product, the price being raised to 87.60 the 200 

 pounds, instead of $6.55, at which it could be bought the past year. 



Nitrate of Potash. 



This salt, also designated under the name of salt of nitre, or nitre, 

 is formed of nitric acid and potash : 



Nitric acid 53.41 



Potash 46.59 



100.00 



By reason of 14 of azote to 54 of nitric acid, it contains 13.8 of 

 azote in its pure form ; that of commerce contains only 12 to 13. 

 Nitrate of potash is obtained by decomposing, under vast sheds for 

 this purpose, substances of animal origin, mixed with argil ocalcareous 

 earth, which is then washed in ley to extract the nitre. This salt has 

 for a long time been made from rubbish. It is made now by decom- 

 posing the chlorine of potassium by means of nitrate of soda. By 

 this we obtain both the chloride of sodium (marine salt) and nitrate 

 of potash, very easy to separate by crystallization. Nitrate of potash 

 is of all substances containing potash the most suitable to agri- 

 cultural wants. 



Nitrate of potash is now worth $5.40 the 200 pounds. 



Phosphate of Lime. 



Under the name of phosphates of lime are comprehended a great 

 number of different products. For a long time agriculturists only 

 used the phosphate of lime from bones. It was then associated with 

 carbonate of lime. Now, the greater part of the phosphates used as 

 fertilizers are provided by the mineral kingdom, where it is found in 

 inexhaustible veins. All the phosphates are formed from phosphoric 



