IV.] MANUFACTURED PHOSPHATES 135 



phoric acid of the island of Gothland, though it is not so 

 effective as basic slag containing an equivalent amount 

 of phosphoric acid. While extensively used in Sweden, 

 it does not find its way into this country. 



Wolter Phosphate is made by melting together in a 

 regenerative furnace 100 parts of powdered phosphorite, 

 70 parts of acid sodium sulphate, 20 parts of carbonate 

 of lime, 22 parts of sand and 6 or 7 parts of coke, the 

 molten material being run into water and then finely 

 powdered. The resulting phosphate is almost wholly 

 soluble in dilute citric acid and has proved in experi- 

 ments to be more assimilable by the plant than 

 phosphoric acid in basic slag, and almost equivalent 

 to phosphoric acid in superphosphate. At present the 

 cheapness of basic slag and superphosphate prevent 

 any wide distribution of fertilisers of the type of Wiborg 

 and Wolter phosphates, though they may be remunera- 

 tive in a locality where some waste phosphatic material 

 is available. 



