28 Chemical Composition and Commercial Value of 



been carefully ascertained ; in several the magnesia, sand, car- 

 bonic acid, and the small amount of sulphuric acid and oxide 

 of iron and alumina which generally occur in bone-ash, have 

 been determined : 



Detailed Analysis of South American Bone-ash. 



For analyses required for practical purposes, it is, indeed, 

 unnecessary and often impossible to determine accurately all the 

 constituents besides the phosphoric acid ; but whether two or 

 half-a-dozen constituents are determined, the analytical results 

 should be correct, and be stated in such a manner that manufac- 

 turers and agriculturists who prefer making their own super- 

 phosphate, can make use of an analysis as the basis for calculating 

 the amount of acid which will be required for rendering the bone- 

 ash soluble. The method most commonly used for determining 

 the phosphates, as well as the present mode of stating the results, 

 are equally objectionable. I would, therefore, recommend for 

 adoption the method and the mode of stating the results adopted 

 in analysis No. 4. In this, it will be seen, phosphoric acid, lime, 

 and sand are the only constituents that have been determined 

 separately ; moisture and organic matter are ascertained together, 

 and all the rest by difference. 



PURE BONE-ASH. 



I have asserted that the amount of phosphate of lime found 

 in commercial bone-ash is frequently overstated, and that the 



