In determining the availability of the phosphoric acid in the slag 

 this station employs the Wagner method.'' The average per cent of 

 total phosphoric acid in the four samples examined was 17.71 of 

 which 15.48 per cent or 87.4 per cent of the whole was available, 

 showing them to be of excellent quality. The commercial value of 

 a pound of the available phosphoric acid has been placed at four 

 cents. 



The trade values of fertilizing ingredients in raw 



Schedule of materials and chemicals for the season of [908 



Trade Values, remain the same as for the previous year. They 



represent the average pound cost at retail of the 

 various forms of nitrogen, phosphoric acid and potash furnished in 

 unmixed raw materials and chemicals in the New England and 

 Middle States, during the six months preceding March i, 1908. 

 They are the values agreed upon by representatives of the experi- 

 ment stations in New England and the Middle States after a careful 

 study of prevailing prices in the large cities in these localities. 



TRADE VALUES OF FERTILIZING INGREDIENTS IN RAW MATERIALS 

 AND CHEMICALS FOR I908. 



Nitrogen. 



Cents per pound. 



Nitrogen in ammonia salts, • ^7/^ 



" " nitrates, j8^ 



Organic nitrogen in dry and fine ground fish, meat, blood, 



and in high grade mixed fertilizers, 20)2 



" " " fine* bone and tankage, 20^ 



" " " coarse* bone and tankage, 15 



Phosphoric Acid. 

 Phosphoric acid soluble in water, 5 



" " " in ammonium citrate, (reverted 



phosphoric acid), ■ 4 1-2 



" " in fine* ground bone and tankage, 4 



" " in coarse* bone and tankage, 3 



" " in cottonseed meal, linseed meal, castor 



pomace and ashes, 4 



" " insoluble (in neutral citrate of ammonia 



solution) in mixed fertilizers, 2 



Potash. 

 Potash as sulphate, free from chlorides, 5 



" " muriate (chloride), 4^ 



" " carbonate, 8 



* Fine and medium bone and tankage are separated by a sieve tiaving circular openings 

 1-50 of an incli in diameter ; valuations of tliese materials are based upon degree of fineness 

 as well as composition. 



- See Koenigs L'ntersuchung landwirtschaftliclie und sewerbliche wichtiger Stofte, Dritte 

 Auflage, p. I73-I74. 



