The less lime in combination the more soluble the phosphate. 

 Consequently we find three-lime phosphate the least soluble anil one- 

 lime phosphate the most soluble of the fir.st three compounds. 



By mixing ground bone with enough (IGO pounds of pure) sul- 

 furic acid to combine with two parts (112 pounds) of lime, a 

 bone-meal superpliosphate is produced. Such a product has very 

 undesirable physical properties. By mixing with enough (80 pounds 

 of pure) sulfuric acid to combine with one part (.tO pounds) of lime, 

 a "dissolved bone-meal" is produced. See page 16. 



HISTORICAL. 



Bones are said to have been first employed to a large extent, as a 

 fertilizer, in 1794. For some time they were applied without being 

 treated in any manner. During the first three-fourths of this century 

 they were composted with many kindsof material, especially with lime,, 

 ashes and animal refuse. In 1840, superphosphate was first made 

 by Liebig, who accomplished this by " dissolving" bones with sul- 

 furic acid. Shortly thereafter Sir John Lawes manufactured 

 " superphosphate of lime" by this process. Bones were soon ground 

 to " bone-meal." This method of treatment has been highly devel- 

 oped, so that now a large variety of products known by the general 

 term of bone-meal are made. The varietits considered in this 

 bulletin are raw bone-meal, produced by simple grinding, steamed 

 bone-meal by steaming and grinding, and "glue-free" bone meal, 

 obtained by grinding wliat remains after the glue has been removed 

 from the bones by cooking. These are each further classified accord- 

 ing to the fineness of their particles. 



1'lie fineness of a bone-meal is ascertained by passing the material 

 through a series of sieves, with meshes of regularly decreasing size,. 

 and weighing the different siftings. An illustration of this process, 

 is found on page 8. 



It has long been held that phosphoric acid in bones and bone-meal 

 is in such form, as to be quickly available to plants, when applied to 

 the soil. 



Bone-meal has been considered profitable for application to light, 

 sandy soils, especially lo those low in phosphoric acid. 



During the past decade many tests have been made by various 

 experimenters, to determine the actual availability of this form of 

 phosphoric acid, as compared with that in Apatite, South Carolina 

 Phosphate, and other mineral phosphates, as well as superphosphates.. 



