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X. — Oil the Solubility of Pliosphatic Materials, with special 
Reference to the Practical Efficacy of the various Forms in lohick 
Bones are used in Agriculture. By Dr. AUGUSTUS Voelcker. 
The comparative efficacy of bones, superphosphate of lime, 
coprolites, and other purely phosphatic materials, depends in a 
great measure on the facility with which they pass into the 
watery liquids present in cultivated soils from which plants 
derive their nourishment. 
Coprolites, apatite, rock-guano, and other varieties of mineral 
phosphates, scarcely produce a visible effect upon vegetation, 
even when they are applied to the land in a finely powdered 
condition and in large quantities, because they are not readily 
soluble in water, and consequently cannot be assimilated by our 
crops in quantities sufficient to promote a luxuriant growth. 
In order to render mineral phosphates more useful, the manu- 
facturing chemist, as is well known, dissolves them in sulphuric 
acid, or, in other words, converts them into superphosphates. 
Experience has not only proved this to be an economical way 
of utilising mineral phosphates for agricultural purposes, but 
has likewise shown it to be the only available means of converting 
the inactive phosphatic minerals into powerful artificial manures. 
If it be an admitted fact that such materials in a state of fine 
powder are of little practical utility to the farmer, it follows that 
manure-manufacturers should render phosphatic minerals as 
completely soluble as possible by chemical treatment with acid. 
It may, however, be questioned whether this proceeding is 
equally well adapted or equally necessary for converting bone- 
dust, boiled bones, ivory-dust, and such like materials, into 
efficacious artificial manures. 
It is found that in porous soils, even half-inch bones are 
sufficiently soluble to yield abundance of phosphatic food to the 
turnip crop, in accordance with the practice of many good far- 
mers. It is moreover well known that the intimate admixture 
of phosphate of lime with decomposing organic matters favours 
the solution of the phosphate, and likewise that phosphkte of 
lime is more soluble in the presence of ammoniacal salts than it 
is in pure water. 
The various conditions which affect the solubility of phosphate 
of lime in water therefore have a direct practical bearing on the 
application of bone manures in agriculture. 
In the present paper I purpose giving a brief account of an 
experimental inquiry having for its object to determine the 
extent to which various phosphatic materials are soluble in 
water and in some saline solutions. Having directed my atten- 
