MANUFACTURE OF NITRATE OF LIME 317 



13 to 20 centimeters in diameter. The carbonate of lime is em- 

 ployed in quantities suitable to neutralize completely the acid 

 solution and to produce neutral nitrate of lime. This operation 

 is conducted methodically in four superimposed vessels. Upon 

 the fresh carbonate the solution which has been almost neutralized 

 is brought. The fresh acid is placed in contact with the residue 

 of lime which has not been dissolved by the first treatments with 

 the partially saturated solution. By reason of their superposition 

 the movement of the liquid in the vessels is operated automat- 

 ically. Finally, there is obtained a solution of neutral nitrate of 

 lime which is conducted into evaporation vessels. The concen- 

 tration of the liquid is accomplished partially by the aid of steam 

 coming from the boiler used for the cooling of gases escaping 

 from the electric furnace, as has been previously described, and 

 partially in a direct manner. The solution of nitrates is reduced 

 to such a concentration that their boiling point rises to 145, 

 which gives a liquid containing from 75 to 80 per cent, of nitrate 

 of lime, equivalent to from 15.2 to 15.5 per cent, of nitrogen. 

 This viscous mixture is poured into vessels of 200 liters capacity 

 and allowed to solidify by cooling. The nitrate can be shipped 

 either in this state or after powdering. 



Instead of evaporating the nitrate of lime until the liquid 

 has obtained a boiling point of 145, it may be allowed to crys- 

 tallize after having been evaporated to 120 only. The crystals of 

 nitrate of lime are then separated in a centrifugal. Finally there 

 is manufactured at Notodden some basic nitrate of lime by 

 adding to the hot solution a proper proportion of quicklime. 

 After cooling, the product is broken up and passed through a 

 .sieve. The basic nitrate contains about 10 per cent, of nitrogen. 

 It goes without saying that by the process just described there 

 -can also be manufactured nitrate of soda, or potash, in place of 

 nitrate of lime. It is the cheapness of the lime, however, as com- 

 pared with soda which has led the manufacturers at Notodden 

 to transform the nitric acid into calcium nitrate. 



The actual production of nitric acid at Notodden amounts to 

 from 500 to 600 kilograms per kilowatt-> ear. The factory, which 

 lias been running since the 2d of May, 1905, has produced in one 



