Phospluitic Materials used for Afjricultimil Purposes. 375 
been caroliilly 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. 
1 
No. 1. No. 2. 
No. 3. 
No. 4. 
: No. 5. 
Lime not united with phos-l 
Insoluble siliceous matter (sand) 
Oxide of iron and alumina . . 
Alkalies, carbonic acid, and loss 
*Forming together bone-earth 1 
(tribnsic phosphate of lime) J 
4-83 
4-06 
35-38 
41-27 
o Do 
6-95 
-97 
3-01 
9-91 
1-75 
33-89 
39-53 
'I U / 
8-32 
-99 
•78 
1-39 
15-341 
2 - 03 ) 
32-52 
37 - 84 
1-92 
6-51 
1-48 
-84 
-37 
-21 
-84 
(By 
diSference) 
3- 29 
38-12 
44-47 
4- 45 
3-90 
5- 67 
/ 
10-30 
29-56 
34-48 
1-02 
20-24 
•77 
3-63 
100-00 
100-63 
100-00 
100-00 
100-00 
76-65 
73-42 
70-46 
82-59 
64-04 
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 
