44 FERTILISERS CONTAINING NITROGEN [chap. 



fifth and last tower the absorbing liquid is milk of lime, 

 and the resulting mixture of solution of calcium nitrite 

 and nitrate is treated with enough of the previously- 

 formed nitric acid to convert it wholly into nitrate, 

 the nitrous fumes evolved being led back into the oxi- 

 dising chambers. The product is then concentrated 

 until it solidifies as a material containing about 13 

 per cent, of nitrogen, or 75 per cent, of pure calcium 

 nitrate. 



The present factory has three electric furnaces 

 installed, each employing 500 kilowatts, and the pro- 

 duction amounts to about 150 kilogrammes of nitrogen 

 fixed per kilowatt year. 



Berkeland calculates that the cost of manufacturing 

 calcium nitrate containing 13 per cent, of nitrogen 

 is about £/\. per ton, and that it can be sold at a 

 profit at ;;^8 a ton, which would be equivalent to nitrate 

 of soda at about ;^io a ton. The present large factory 

 at Notodden has been putting calcium nitrate on the 

 market for two years or more, the rate of pro- 

 duction now being about 20,000 tons per annum. 

 When the extensions to the factory are completed it 

 is expected the output will amount to nearly 3000 tons 

 per month. As a fertiliser there cannot be the least 

 doubt that nitrate of lime will be just as valuable, 

 nitrogen for nitrogen, as nitrate of soda. At Rotham- 

 sted a chemically prepared nitrate of lime has been 

 used for two or three years for a special purpose on one 

 of the mangold plots, and it has given exactly equal 

 results to the nitrate of soda plot alongside. Many 

 field experiments have also been carried out with the 

 electrical product in Norway during the last year or 

 two, and have shown that the new material can be 

 strictly valued against nitrate of soda on the basis of 

 the nitrogen it contains. Indeed, on some soils it 



