SUBSTITUTES FOB BASIC SLAG. 163 



to the linear inch, i.e., 10,000 to the square inch. Thomas 

 phosphate has given excellent results, especially in soils some- 

 what deficient in lime and rich in organic matter. 



The magnitude of the trade in basic slag may be gathered 

 from the accompanying table giving the quantity sold as a 

 fertiliser in Europe during 1899. * 



Sold. Used in the country. Exported. 

 Tons. Tons. Tons. 



Germany ... 786,000 730,000 56,000 



Great Britain ... 256,000 110,000 146,000 



France ... 198,000 198,000 



Belgium ... 112,000 80,000 32,000 



Austria Hungary 64,000 90,000 f 



Total ... 1,416,000 1,208,000 234,000 

 So successful has Thomas phosphate proved as a manure 

 that lately a product known as "artificial Thomas phosphate 

 meal " has been made in Germany by a method devised by 

 Wolters. Eaw mineral phosphates are fused with silicious 

 materials, e.g., sand or glass, and chalk or limestone, and a 

 product resembling basic slag is thus obtained. In another 

 preparation potash is introduced. According to analyses of the 



two products by Maerckert they contain 



i. ii. 



Total phosphorus pentoxide ... 15-50 % 16*89% 

 Phosphorus pentoxide soluble in 



citrate solution ... ... 14-52% 15'38% 



Lime ... ... ... 41-80% 



Silica ... ... ... 26-83% 



Potash ... ... ... 13-10% 



Another product of somewhat similar character as to citrate- 

 solubility of its phosphates is the so-called Wiborgh phosphate, 

 another German product. It is prepared by heating the crude 

 phosphate (mainly apatite), containing some felspar, with soda- 

 ash, to about 1000 C. 



The reactions are said to be 



3(Ca 3 P 2 8 ).CaF 2 + 3Na 2 C0 3 



= 2Na 2 0.10Ca0.3P 2 5 +2NaF + 3CO 2 



K 2 O.Al 2 3 .6Si0 2 + 2Na 2 GO 3 ^K 2 O.2Na 2 O.Al 2 O 3 .6SiO 2 +2CO 2 



* Engineering and Mining Journal, 69, 648. Jour. Soc. Chem.' Ind. 1900, 574. 



t 26,000 tons were imported, chiefly from Germany. 



J Jahresbericht Agricultur-Chemie 1899, 129. 



M2 



