EXPERIMENT STATION. 27 



perphosphates and the increased attention given to that class of 

 fertilizers during 1881 is encouraging evidence that consumers 

 are studying the wants of their soils more carefully than has for- 

 merly been the custom. 



Sample 635 is from one of the sets of fertilizers supplied for 

 experimental purposes as suggested by Prof. Atwater. It is of 

 unexceptionable quality for its purpose. 



For Analyses, etc., see pp. 28 and 29. 



Nitrogenous Superphosphates, Guanos,* etc. 



Under this heading are reported the various commercial fertili- 

 zers, except so-called " special fertilizers" which have been ana- 

 lyzed at the Station, that contain, or are claimed to contain any- 

 considerable amount of phosphoric acid soluble in water, and also 

 of nitrogen. 



This list includes 16 " phosphates," and " superphosphates," 

 variously designated, 8 " guanos" native and manufactured, 2 

 "Matfield Fertilizers," 2 "Mapes' Complete Manures," an " animal 

 fertilizer," a "fish and potash" and a " bone dissolved in sulphu- 

 ric acid," making a total of 31. "Thirteen other analyses of su- 

 perphosphates have been made for private use. Of these fertili- 

 zers, 24 contain potash in smaller or larger quantity. 



In the table they are arranged in the order of the excess of 

 estimated value over cost or of cost over estimated value. 



For Analyses, etc., see pp. 30, 31, 32 and 33. 



The percentage of chlorine is an indication as to whether muri- 

 ate of potash or kainite has been used in the manufacture. 35^ 

 parts of chlonne in muriate of potash correspond to 47 of potash. 

 High grade sulphate of potash is free or nearly free from chlorine. 



The " comparison of different samples of the same (or similar) 

 brand," see page 34, mostly explains itself. Dickenson's super- 

 phosphate, a new article, manifests much more fluctuation in 

 composition and value than will probably appear when the manu- 

 facturing process becomes settled by experience. 



Peruvian guano now varies in value unpleasantly. The ancient 

 rich deposits it is said are quite exhausted. What comes into 

 market is therefore presumably of inferior value. Rumor has it 

 also that very inferior or adulterated shipments from England 

 have been coming to this country for disposal, and consumers 

 would do well not to purchase without guaranty of composition. 



* For " The Bird Guano and Fertilizer " see page 58. 



