December 24, 1920] 



SCIENCE 



613 



That the phenol reagent is not specific has already 

 been pointed out by Abderhalden, who found oxy- 

 proline and tryptophane to yield positive results. 

 E. A. Gortner has also observed a positive response 

 by indol. On further study we have found the 

 color reaction to be given by a very large number 

 of inorganic and organic substances, among which 

 may be mentioned cuproua and ferrous salts, 

 bromides, iodides, nitrites and sulfites, amines, 

 aldehydes and ketones, carbohydrates, especially 

 glucose, amyl alcohol, benzyl chloride, benzoyl 

 chloride, benzidine, hydroxylamine, phenylhydra- 

 zine, phenolphthalein, haematoxylin, naphthyla- 

 mine, animal charcoal, etc. Generally speaking the 

 reagent seems to be affected by all sorts of sub- 

 stances possessing more or less reducing proper- 

 ties. In comparison to other methods the Folin 

 and Dennis procedure for phenol in urine gives 

 higher results, which may be accounted for by the 

 presence of uon-phenolic compounds reacting with 

 the color reagent. 



of some raw starches: C. F. Lang- 

 ■WORTHY and Hakry J. Duell, Jr. In the ex- 

 periments here reported, the digestibility of raw 

 arrowroot (Zamia floridana), cassava, and rice 

 'starches was determined when eaten in quantities 

 of approximately 150 grams per day by normal 

 men. They were eaten as a constituent of a frozen 

 custard. Raw cassava and rice starches were com- 

 pletely digested and no trace of them could be 

 found in the feces. The average of these experi- 

 ments on arrowroot starch varying from 65.0 to 

 99.3 per cent, was made 82.2 per cent. The sub- 

 jects remained in normal health during the three- 

 day experimental period and no abnormal physio- 

 logical effects were noted. 



Uses in iiologioal sciences for standardized, ster- 

 ile buffer tablets, and for a single sterile buffer 

 solution covering all Pj^ values: Pauline M. 

 Avery, R. E. MELLOisr and S. P. Agree. Studies 

 of growth, respiration, sporificatiou, reproduction, 

 physiology and morphology can be made with bac- 

 teria, fungi and molds, as well as with higher 

 plants and animals, by the use of buffer tablets 

 containing standardized quantities of desired chem- 

 icals giving definite hydrogen ion concentrations. 

 Such tablets or mixtures may also contain stand- 

 ardized quantities of desirable indicators, dyes, 

 colloids or other materials. Sterile culture media 

 with or without agar can be given any desired 

 acidity or Ph value by the addition of sterile 

 buffer tablets, with or without indicators. Such 



Ph value may be made the minimum, optimum or 

 maximum for the organism in order to stimulate 

 or to suppress its growth or some other function, 

 and this method can be made diagnostic for mix- 

 tures of organisms. By employing a suitable com- 

 bination of photometer and turbidimeter or 

 nephelometer, the hydrogen ion and indicator 

 changes can be investigated, along with changes 

 in colloidal conditions in solutions or agar-like 

 gels. Such an apparatus as that devised by Shep- 

 pardi can be used for measuring the rate of 

 growth of bacteria along with hydrogen ion 

 changes, or the rate of development of spores in 

 fungi. Colloidal and dispersed conditions in soil 

 extracts, plant extracts, pulp liquors, milky solu- 

 tions or suspensions of all kinds, and waters of 

 lakes and streams, can be studied accurately along 

 these lines, together with hydrogen ion concentra- 

 tions. A single sterile buffer solution covering all 

 Ph values when treated with acid and alkali, has 

 been tested thoroughly and replaces the five or 

 six solutions used by other workers. Such a 

 single buffer solution and the standardized buffer 

 tablets simplify the chemical side of exact re- 

 searches in biology to such an extent that the 

 methods can be used without chemical control by 

 the biologist aud consequently save his time for 

 use in his own research field. 



On th-e ionization constants of glycerophosphoric 

 acid and the use of ca/rhohydrate phosphates as 

 buffers and nutrients, especially in culture media: 

 Pauline M. Aveky, E. E. Mellon and S. P. 

 Agree. Glycerophosphoric acid has ionization 

 constants about Kj = 2.5 X lO-''. These values 

 are so close to those of phosphoric acid that the 

 latter can be replaced as a buffer to advantage for 

 several reasons. Glycerophosphates, sucrose and 

 mannite phosphates and others are sources of 

 carbohydrate food as well as of phosphorous. 

 Over 20 organisms, including tubercle bacilli, have 

 been grown on such buffered glycerophosphate 

 media adjusted to different Ph values. The 

 sodium and other glycerophosphate salts can be 

 made and kept in anhydrous form, easier to 

 handle and weigh than sodium phosphate. The 

 glycerophosphate titration curve is sufficiently 

 close to that of phosphates to replace it in all 

 work when corrected. The calcium, magnesium 

 and other salts of glycerophosphoric acid are sol- 

 uble in contrast with the insolubility of the phos- 

 phates and can be used to study the effect of 

 such metallic ions on growths and other func- 



ij. Ind. Eng. Chem., 12, 167. 



