26 THE CONNECTICUT AGRICULTURAL 



2 nitrate of soda. 



1 salt. 



2 land plaster. 

 5 ashes. 



1 refuse lime. 



1 limestone. 



2 marls (one styled " bird guano"). 



3 soap boilers' refuse. 



1 mussel bed. 



2 swamp muck. 



9 miscellaneous, private. 



170 



Plain (non-nitrogenous) Superphosphates. 



These fertilizers are either prepared by treating bone black (cal- 

 cined bones, see p. 67) or some high grade native phosphate with 

 sulphuric acid, or are the result of a manufacturing process by 

 which low grade phosphates, such as South Carolina rock, are con- 

 centrated. None of them contain any essential quantity of 

 " bone" in the usually received and proper sense of that word, as 

 is proved by the nearly total absence of nitrogen. Sample 554, 

 being designated "Dissolved Ground Bone," was analyzed for nitro- 

 gen and 0.21 per cent, of that element was found. All the samples 

 made from bone black contain a similar quantity of nitrogen, but 

 this nitrogen is of little or no fertilizing value. 



Of the nine samples examined during 1881, seven are of excel- 

 lent and nearly uniform quality, most of their phosphoric acid 

 being soluble in water. Two are exceptional ; of these, 634 is 

 an excellent fertilizer containing a total of 19^^ per cent, of phos- 

 phoric acid, of which 18|^ per cent, is available, although 8^ per 

 cent, is not soluble in water. 554, the only sample whose cost ex- 

 ceeds valuation, was not well prepared and contained 4.2 per cent, 

 of insoluble phosphoric acid. 



The average cost of soluble phosphoric acid, viz : 11.1 cents 

 in the six best samples whose price is given, is well within the 

 valuation, 12i cents, that has been hitherto employed by the 

 Station. 



It is a fact that has been made conspicuous in former reports 

 that soluble phosphoric acid is most cheaply and most certainly 

 obtained in the high grade non-nitrogenous (not ammoniated) su- 



