FERTILIZERS. 483 



FERTILIZERS. 



On the effect of composting on certain phosphates, T. Pfeiffer 



and n. Thukmann Landir. Vers. iSfat., ■J7{Js9(i), So. 4-5, 2)p. 313-356). — 

 Tlie literature of the subject is reviewed, aud as preliminary to the 

 main investigation different metliods of determining x^hosphoric acid 

 weie tested on pure monopotassiuni i)hospliate, and various commer- 

 cial phosphates, some of which are used as manure i)reservatives. 

 With the molybdic method in the first case (with pure phosphate) there 

 was no difference whether the solution was allowed to stand 12 hours 

 or heated 20 minutes in a boiling- water bath. A large excess of mag- 

 nesia mixture gave too high results. Direct precipitation from citrate 

 solution gave good results. 



Citrate solutions of superphosphate- gypsum, "magnesia-preparation" 

 "precipitate," double superphosphate, and crude phosphate were pre- 

 pared by Wagner's method and tested by various methods. In the 

 cases of precipitate and double superphosphate, the further addition of 

 citrate solution was necessary before exact results could be obtained 

 by precipitation with molybdic solution and magnesia mixture. The 

 eft'ect of varying the amount of solvent used was also tested. The first 

 two dissolved more readily when the proportion of solvent to material 

 was 500 cc. to 5 gm. than when it was 500 cc. to 2.5 gm. With 2 per 

 cent citric acid solution the larger the proportion of solvent to material 

 the greater the amount of phosphoric acid dissolved in every instance. 



A compost of ground peat and urine was prepared and portions were 

 placed in flasks, to which the various preservative materials M^ere added. 

 The mixtures were weighed and examined June 10 and allowed to stand 

 until December 19, when they were weighed aud examined again to 

 determine changes in both phosphoric acid and nitrogen. Where the 

 crude phosphate and magnesia preparation were used as preserva- 

 tives there was a practically insignificant increase of citrate soluble 

 phosphoric acid. With the superphosphate-gypsum, on the other 

 hand, there was such a great decrease as to indicate the formation of 

 tricalcium phosphate from monocalcium and dicalcium i^hosphate in 

 the presence of the ammonia and ammonium carbonate formed. 



There was a considerable loss of nitrogen from the compost in every 

 case, but it must be remembered that a large part of the nitrogen was 

 originally in a very easily decomi)osal)le form. It appears, however, 

 that the use of preservatives is at best only one of the means of pre- 

 venting the loss of fertilizing value of manure. The proper construc- 

 tion of the manure heap is probably a more important means. 



The value of leather refuse, J. B. Lindsey {Jour. Amer. Chem. Soc, 

 18 {1896), No. 7,p}). 565-575). — This records a continuation of work com- 

 menced in 1894,' and gives the results of experiments on oats during 



'Massachusetts State Sta. Rpt. 1894, p. 290; Agl. Sci., 8 (1894), Nos. 2, p. 49j 3, 

 p. 98. 



