16 



VOELCKER on the Value of Artificial Manures. 



The following table exhibits the composition of four samples 

 of good superphosphate, recently sent to us for analysis : 



Composition of 100 parts of good Superphosphate of Lime. 



Water 



Organic matter 



Soluble phosphate of lime 



equal to bone-phosphate . . 

 Insoluble bone-phosphate 

 Hydrated sulphate of lime 



(gypsum) 



Alkaline salts 



Sand 



25-10 

 5-16 



5-82 



20-33 

 6-60 

 5-30 



28-39 

 1-56 

 6-73 



24-76 

 2-33 

 6-66 



100-00 100-00 100-00 100-00 

 1-66 not -853 not 



2-01 determined. 1-065 determined. 



Percentage of nitrogen . . 

 Equal to ammonia 



The two former samples were obtained from two different 

 Southampton manufacturers, and the two last from a Bristol 

 manufacturer. 



In the next table the analyses of two adulterated samples are 

 given : 



Composition of two adulterated samples of Superphosphate. 



I. 



Water 14-40 



Organic matter* 8-93 



. 3-60 

 (5-61) 

 6-83 

 44-20 



Soluble, or bi-phosphate of lime 



equal to bone-earth 



Insoluble, or bone-phosphate . . 

 Hydrated sulphate of lime (gypsum) 



Burned gypsum .. .. .. 



Alkaline salts 2-52 



Insoluble siliceous matter (principally 



quartz sand) 19-50 



Containing nitrogen 

 Equal to ammonia . . 



100-00 

 1-44 

 1-75 



II. 



22-03 

 trace. 



8-55 



(13-33) 



none. 



24-42 



40-43 



2-41 



2-16 



100-00 

 17 

 20 



No. I., it will be observed, is very much adulterated with 

 sand and gypsum, and contains only 3'6 per cent, of soluble and 

 6 '8 per cent, of insoluble phosphate of lime. 



No. II. evidently was prepared by dissolving bone-ash in sul- 

 phuric acid, and drying up the pasty mass with no less than 40 

 per cent, of burned gypsum. 



The adulteration of sand in superphosphate is readily de- 

 tected, but not that of gypsum. When bone-dust or bone-ash is 

 dissolved in sulphuric acid, sulphate of lime or gypsum neces- 

 sarily is formed ; it being thus present in all samples of super- 



