694 



SCIENCE 



[Vol. LVI, No. 1459 



a 'large amount of limestone (8 to 10 tons in 

 addition to that required to remove the red color) 

 will be required. In some instances the cost of 

 this large amount may be prohibitive. 



The effect of selenium compounds upon the 

 growth and germination of plants: Victor E. 

 Levine. The findings of Gassmann (zs. Physiol- 

 Chem., 1917, 100, 209) that selenium ia a con- 

 stituent of plants has led to the inquiry as to the 

 effect of selenium compounds upon germination 

 and growth. White lupine and timothy seedlings 

 were used in the experiments. Concentrations of 

 0.001 per cent, to 0.0001 per cent, show no injuri- 

 ous effect; in some experiments these concentra- 

 tions favor growth. Concentrations of 0.01 per 

 cent, and over are exceedingly inimical to ger- 

 mination and to growth. The compounds may be 

 arranged as follows in the order of diminishing 

 toxicity: selenious acid, selenic acid, sodium 

 selenite, sodium selenate and potassium seleno- 

 eyanate. This order agrees well with that ob- 

 tained with animal experiments testing the rela- 

 tive toxicity of these compounds. It is evident 

 from the results obtained that selenium can not 

 replace sulfur in the nutrition of plants. 



The determination of nitric nitrogen in the 

 soil solution: Walter Thomas. The determina- 

 tion of nitric nitrogen is the tete noir of the soils 

 chemist. Inasmuch as the phenoldisulfonie acid 

 method is the one that is the simplest and most 

 rapid, and therefore more generally used by soil 

 chemists than any other, the author has carried 

 out some experiments on the effect of various 

 flocculating and clarifying agents under carefully 

 controlled conditions by this method and com- 

 pared the results with the Devarda reduction 

 method, which is the only one that has escaped 

 serious criticism. The results obtained by dif- 

 ferent investigators have been very conflicting, 

 but the results of the present investigation indi- 

 cate that: (1) The use of either potash alum or 

 alumina cream (even if neutral) results in large 

 losses of NO3; (2) CaO if freshly ignited is the 

 most satisfactory flocculating and clarifying 

 agent; (3) The Devarda alloy method gives ex- 

 cellent results on the soil solution, but is not ap- 

 plicable to rapid routine work. 



DIVISION OF FERTILIZER CHEMISTRY 



F. B. Carpenter, chairman 

 H. C. Moore, secretary 

 Water-soluhle nitrogen i7i mixed fertilisers: 

 E. N. Brackett. 



Studies on the availability of organic nitro- 

 genous compounds: C. S. Robinson. 



Review of methods of determining nitrogen in 

 fertilizer: E. W. Magrtjder. 



Possibilities in the use and preparation of con- 

 centrated fertilizers: William H. Eoss. The 

 Haber and other processes for fixing nitrogen 

 and the volatilization method of preparing phos- 

 phoric acid all yield materials, directly or by 

 combination, of different composition and higher 

 concentration than those ordinarily used in the 

 manufacture of fertilizers. Some of these mate- 

 rials, as ammonium phosphate, have chemical and 

 physical properties which make them admirably 

 suited for mixing with ordinary fertilizer mate- 

 rials, or for making mixed fertilizers of higher 

 concentration than any now in use. Others, as 

 ammonium nitrate, can not be satisfactorily used 

 in present fertilizer mixtures unless means can 

 be devised for eliminating or neutralizing prop- 

 erties which interfere with their use in this way. 

 The work of the Bureau of Soils on concentrated 

 fertilizers and fertilizer materials was therefore 

 undertaken not with a view to replacing the or- 

 dinary fertilizer materials, nor of providing high 

 quality fertilizers which would command higher 

 prices per unit, but rather witli the double pur- 

 pose of devising means of utilizing new sources 

 of fertilizer materials and of decreasing the cost 

 of handling and transporting fertilizers by 

 increasing the concentration of mixtures which 

 require shipment to a distance. The advantages 

 and disadvantages of low-grade fertilizer mix- 

 tures are discussed and a review given of progress 

 made in the preparation of concentrated fertilizer 

 materials. 



Recent investigations on the oxidation of 

 sulfur iy micro-organisms: J. G. Lipman. There 

 has been isolated at the New Jersey Agricultural 

 Experiment Station a new sulfur-oxidizing organ- 

 ism which has been named Thiobacillus tliioxidans. 

 This organism grows readily in purely inorganic 

 media containing, aside from the usual mineral 

 salts, elementary sulfur. It derives its energy 

 from the oxidation of sulfur and obtains its car- 

 bon from carbon dioxide. It will grow readily 

 in a medium having a hydrogen-ion concentration 

 of 4.0 to 5.0 and will continue to multiply when 

 the hydrogen-ion concentration exponent is below 

 1.0. The sulfur is oxidized by this organism to 

 sulfuric acid. The acid so produced may be 

 utilized for a variety of purposes. Mixtures of 

 mineral phosphates and sulfur, properly inocu- 

 lated with Thiobacillus thioxidans, will be con- 

 verted into acid phosphate. Inoculated sulfur 

 added to the soil will increase its acidity to a 

 point where certain objectionable fungi, like those 



