Mar. II. 1918 Nitrifying Bacteria and Tricalcium Phosphate 675 



Table II. — Effects of nitrification on the solubility of tricalcium phosphate in soil 



Materials added. 



Control 



Calcium carbonate 



Tricalcium phosphate. . 



Calcium carbonate and 

 tricalcium phosphate. 



Ammonium sulphate . . 



Ammonium sulphate 

 and calcium car- 

 bonate 



Ammonium sulphate 

 and tricalcium phos- 

 phate 



Ammonium sulphate, 

 calcium carbonate, 

 and tricalcium phos- 

 phate 



Dried blood 



Dried blood and cal- 

 cium carbonate 



Dried blood and trical- 

 cium phosphate 



Dried, blood calcium 

 carbonate , and trical- 

 cium phosphate 



After 2S days. 



Nitric 

 nitro- 

 gen. 



P. p. m. 



20. O 

 22. o 



21. o 



22. o 

 98.0 



Cal- 

 cium. 



P. p. m. 

 45- o 

 56.5 

 53-5 



59-1 

 219.4 



97.0 254.4 



99.0 217. 7 



100. o 

 91. o 



89.0 



82.0 



253-4 

 107.7 



107. 2 



Phos- 

 phoric 

 acid. 



P. p. m. 



13- I 

 II. 9 



24. 2 



17-3 

 18.5 



18.5 



52.1 



26.6 

 9-7 



9.8 



After s7 days. 



Nitric 

 nifiro- 

 gen. 



111.71 24.3 

 118. 2I 19. 5 



P. p.m. 



25-5 

 29. o 



28.0 



28.0 

 99.0 



99.0 



lOI. o 



90. o 

 90. o 

 88.0 



87.5 



Cal- 

 cium. 



P. p. m. 

 50. 6 

 70.8 

 58.8 



70. I 

 225.4 



Phos- 

 phoric 

 acid. 



P. p. m. 



13.2 

 25.0 



22. 4 

 19.4 



270. 5! 7- 4 



229. 6 



230.4 

 113-9 



140. 2 

 117. 7 



38-0 



13-9 

 10. o 



II- 5 

 22. 2 



18.3 



After IS7 days. 



Nitric 

 nitro- 

 gen. 



P. p.m. 



114. O 



94.0 



Cal- 

 cium. 



Phos- 

 phoric 

 acid. 



P. p. fn. \P, p. m. 



232. I 



218.4 30.0 



116. 4 



5-7 



A series of experiments with the use of silica sand corresponding 

 closely with the preceding soil series was conducted at the same time. 

 The silica sand was obtained from Monterey, Cal., and was free from 

 carbonate, but contained small amounts of feldspar, hornblende, and 

 mica particles, and possibly traces of other minerals. Portions of 1,000 

 gm. each were placed in fruit jars, and quantities of ammonium sulphate, 

 dried blood, calcium carbonate, and tricalcium phosphate were added 

 in duplicate at the same rates and arranged after the same plan as in the 

 preceding soil series. 



Mixed cultures of bacteria were supplied by adding 150 c. c. of an 

 ordinary soil infusion obtained from the soil used in the preceding series. 

 The infusions were quite clouded with suspended matter, which probably 

 included small amounts of various soil constituents. In addition, 50 c. c. 

 of a nutrient solution, composed of 2 gm. of sodium chlorid, 0.2 gm. of 

 magnesium sulphate, 0.5 gm. of potassium sulphate, and 6 drops of a 10 

 per cent solution of ferric chlorid per liter, were thoroughly mixed with 

 the sand in each jar. The jars were loosely covered and incubated at 

 room temperature. 



After periods of 28, 56, 98, and 157 days, quantities containing 200 gm. 

 of dry sand were withdrawn, 500 c. c. of distilled water added, and after 

 shaking vigorously as in the preceding series, were filtered through 



