V.J "REDUCED SUPER-PHOSPHATES." 41 



base their estimates of the value of super-phosphates 

 upon the quantity of soluble phosphate which they 

 contain. As a matter of fact, manufacturers and 

 many farmers know that the reduced super-phosphates, 

 instead of being of less value, are really of greater 

 value for the land, and will be found more valuable 

 fertilizers than before the reduction took place. This 

 appears a somewhat contradictory statement until the 

 cause of reduction is known. The simple fact is that 

 the mono-calcic phosphate which was present in the 

 super-phosphate in the first instance, is diminished in 

 quantity by a portion being changed into the form of 

 bi-calcic phosphate, and this portion which has be- 

 come so changed is no longer estimated by analysis 

 as a soluble phosphate. All that has been so changed 

 in character represents so much loss to the manufac- 

 turer, if he sells simply on the basis of the soluble or 

 mono-calcic phosphate present. At the same time it 

 means an actual increase in the value of the manure, 

 for those farmers who use these " reduced super-phos- 

 phates" find that they are generally more lasting 

 in their action and altogether more valuable man- 

 ures. 



78. This "reduction of super-phosphates" may be, 

 and is produced artificially, by an admixture of finely- 

 pulverized bone. Some of the highly-soluble phos- 

 phate is thus reduced to the slowly-soluble form, and 

 yet the fertilizing power of the manure is increased. 

 Here, as in the case of the reduced super-phosphates 

 already referred to, there would be a serious loss to 

 the manufacturer, if the value were determined by the 

 present system, and accordingly this very useful prac- 

 tice is discouraged. 



79. In the purchase of super-phosphate of lime it 

 is usual for the strength to be described by saying that 

 it contains a certain percentage of soluble phos- 

 phate. As this is a term commonly used in every 

 market town in the country, you should clearly under- 



