No. 4.] CHEMICAL AND FARM MANURES. 143 



this treatment it is usually designated as "ignited" or 

 " roasted" iron and alumina phosphate, " roasted" redonda 

 phosphate or redondite. It is also met with under the 

 name of '< concentrated phosphate." The raw or untreated 

 material has been found in large quantities in certain fertil- 

 izers that have been sold in Rhode Island, and the treated 

 material is doubtless employed quite extensively. This 

 phosphate in its untreated state is generally considered as 

 of no value, though recent reports from the New Hamp- 

 shire station * would tend to show that it proved superior 

 to the ignited product and to basic slag. Sufficient details 

 are not given, however, to enable one to decide as to the 

 probable correctness of these quite unusual conclusions. 

 In the Rhode Island experiments there was little difference 

 upon unlimed soil between the ignited and raw phosphate, 

 the former yielding 4,930 pounds and the latter 5,043 

 pounds of hay. Where phosphoric acid was not employed, 

 the yield was only 2,548 pounds, indicating some effect 

 from the applications of both of these materials. In the 

 limed series the raw or unignited iron and alumina phos- 

 phate appears not only to have been of no benefit but pos- 

 sibly to have worked injury. In the case of the " ignited" 

 product,! o^ the other hand, it ranked slightly above dis- 

 solved bone, and very close to dissolved bone-black, the 

 weights of the hay having been as follows : — 



Pounds of Hay. 



Ignited alumina phosphate, 19,481 



Dissolved bone, 19,281 



Dissolved bone-black, 19,838 



Without phosphoric acid, 15,738 



The various results show, then, most strikingly, that the 

 raw phosphate may be of a little service on a soil deficient 

 in lime, and that liming such a soil does not increase the 

 efficiency of this phosphate. On the other hand, while it is 

 shown that the ignited iron and aluminum phosphate may 

 be of some value on unlimed acid soil, its effectiveness, at 



* Bulletin 59, pp. 189, 190. 



t Merrill in experiments at the Maine station (fourteenth annual report Maine 

 Agricultural Experiment Station, 1898, p. 72), calls attention to results secured by 

 him, showing a similar value of the ignited product in connection with grasses, 

 while with other plants its action was not so satisfactory. 



