50 



SCIENCE 



[Vol. LVI, No. 1437 



strains studied. This is appreciably lower than 

 that reported (pn 6.6-6.8) for two strains by 

 Fred,^ but agrees very closely with the senior 

 writer's findings regarding the maximum hydro- 

 gen-ion concentration tolerated by these organ- 

 isms in soils (ph 5.9-6.0).* 



As the hydrogen-ion concentration of the 

 medium decreased, growth increased until 

 Ph 6.1 to 6.4 was reached. Here growth ap- 

 peared to be quite as vigorous as at lower con- 

 centrations. 



No fixation of nitrogen took place in a 

 hydrogen-ion concentration greater than pn 5.9, 

 while fixation in concentrations of Pn 6.3 to 6.5 

 was as great as in lower concentrations. The 

 optimum reaction for the fixation of nitrogen 

 appeared to be very closely associated with the 

 optimum reaction for growth. 



The total quantity of acid produced by the 

 various cultures was insignificant. The culture 

 medium employed required only about 0.05 

 cc N/1 acid per 100 cc to produce a change of 

 0.1 Ph in reaction. Even with this low buffer 

 index only slight changes in the hydrogen-ion 

 concentration of the medium were produced by 

 the growth of any strain of the organism. This 

 would indicate the production of inappreciable 

 quantities of either acid or basic metabolic 

 by-products by these organisms. 



P. L. Gainey 



H. W. Batchelor 



Kansas Agbicttlttjeal 

 ExpEKiMENT Station 



PRELIMINARY NOTES ON VAUXITE AND 

 PARAVAUXITE 



Among the mineral specimens collected on 

 the Vaux-Academy Andean expedition of 1921 

 are two that have proved to be new. As the 

 crystallographic work on these will take some 

 time, the following brief notes are therefore 

 presented : 



VAUXITE 



Color: Sky-blue to Venetian-blue (Ridg- 

 way) ; streak white. Luster vitreous. Trans- 

 parent. Form: Aggregates of small crystals 



3 E. B. Fred: Jour. Agr. Mes., Vol. 14, pp. 317- 

 336. 



* P. L. Gainey: Jour. Agr. Bes., Vol. 14, pp. 

 265-271. 



tabular parallel to b (010). Hardness 3.5. 

 Specific gravity = 2.45. 



Composition: 4 FeO. 2 AUO3. 3 F,0-. 24 

 H,0 + 3 H,0. 



Crystal system : Triclinic. 



Optical properties : Optically -|- ; a = 1.551 ; 

 13 = 1.555; y = 1.562; all ± .003; y — a = 

 .001 ; 2V — 32° ; Bx^,, emerges on sections par- 

 allel to b (010). Dispersion considerable p>u. 

 Strongly pleochroic, colorless to blue. 



Occurrence : On wavellite from the tin mines 

 of Llallagua, Bolivia. 



Name : In honor of the well-known amateur 

 mineralogist, Mr. George Vaux, Jr., of Bryn 

 Mawr, Pennsylvania. 



PABAVAUXITE 



. Colorless; streak white. Luster vitreous to 

 pearly. Transparent. Form: Small prismatic 

 crystals. Hardness 3. Specific gravity : 2 :30. 

 Composition: FeO. AUOg. P,0,. 6H„0 + 

 5H,0. 



Crystal form : Triclinic. Cleavage, perfect 

 parallel to b (010). 



Optical properties : Optically+ ; a = 1.554 ; 

 P = 1.558; V = 1.573; all ± .003; y — a. = 

 .019; 2V (calculated) 35°. Sections parallel 

 to b (010) show the emergence of an optic 

 axis. 



Occurrence : On wavellite from Llallagua, 

 Bolivia. 



Samuel G. Gordon 

 Academy op Natural 



Sciences of Philadelphia, 

 April 15, 1922 



THE AMERICAN CHEMICAL 

 SOCIETY 



(Contmued) 



SECTION OF CHEMICAL EDUCATION 



Edgar P. Smith, chairman 

 Neil E. Gordon, secretary 



First year college chemistry: William Mc- 

 Phekson. 



A first course in general chemistry: Wilhelm 

 Segekblom. a brief comparison is made of four- 

 teen of the more modern texts in chemistry suit- 

 able for secondary schools. The results of a re- 

 cent text-book survey made by the New England 

 Association of Chemistry Teachers are giren. 

 The usual custom of starting beginners in chem- 



