611 



while the use of either nitroj^en or phosphoric acid alone, and particu- 

 larly of the "complete fertilizer," increased the proportion of grain to 

 straw and cliaft". 



Experiments with potatoes gave similar results, except that contrary 

 to the above, i^otash used alone had a beneficial effect on the yield. 



At the close of this series of expeiiments in 1889, the sod from each 

 plat was analyzed chemically. According to these analyses, the soil 

 from the plats which had received no fertilizer for 21 years contained 

 as much nitrogen as that from those which had received yearly appli- 

 cations of nitrogen. The solution for the estimation of phosphoric 

 acid and potash were made by extracting the samples of soils with 4 

 per cent hydrochloric acid. These extracts of the soil from the unfer- 

 tilized plats contained just as much phosphoric acid and more potash 

 than that from the fertilized plats. In the opinion of the author, the 

 chemical analysis of a soil at the preseut stage of knowledge is no reli- 

 able criterion as to its needs. 



Exceptions were taken by several of the gentlemen present to the 

 method employed for dissolving the i)hosi)horic acid and potash, it being 

 urged that a 4 per cent hydrochloric acid solution might be insufiBcieut 

 in some cases, especially where considerable quantities of lime, iron, 

 etc., were preseut. 



The water-soluble phosphoric acid compounds in superphosphates, J. 

 Stoklasa {Landw. ]^ersuch.s^t(itio)ien, oH^ 2^P- 197-225). — In his investiga- 

 tions the author used pure pre[)arations of monocalcic phosphate, believ- 

 ing that from the results obtained in this way more accurate and reliable 

 deductionsconcerning the relations between phosphoric acid and the con- 

 stituents of the soil could be made than by working with superphosphates 

 which contain the soluble phosi>horic acid in a more changeable form. 

 lie found that a preparation of monocalcic jihosphate so nearly i)ure as 

 to contain only 0.014 per cent of free acid absorbed almost no water 

 (0.2 i)er cent) from the air by lying for 37 days, while a preparation con- 

 taining 9.9 per cent of free phosjdioric acid absorbed, under exactly the 

 same coiulitions, 9.3 per cent of water. A preparation containing 0.1 

 per cent of free acid is somewhat hygroscopic, and this quality increases 

 with the increased content of free acid. 



When these two prei)arations were dried in an oven at 15-20° 0., 

 the chemically pure preparation readily gave up its small amount of 

 wateiand gained its fornuT weight; but after heating tlie other sample 

 (containing 9.9 jx-r cent free acid) at the same temperature for 20 days, 

 it still contained 8.14 per cent of water. When the water was expelled 

 from both preparations they were found to contain exactly the same 

 amounts of free phosphoric acid as before, showing that the water 

 absorbed from the air had caused no decomposition of the salt in either 

 case; in other words, that monocalcic phosi)hate is a stable compound 

 in the air. Steam (80-85° C.) was found to decompose the salt, causing 

 phosphoric acid to be set free. 



