Maech 2, 1906.] 



SCIENCE. 



331 



The Relation hetween Barometric Pressure 



and Carton Dioxide: G. 0. Higley. 

 The Separation of Proteoses and Peptones 



from the Simpler Amido Bodies: W. D. 



BiGELOw and F. C. Cook. 



The paper gives the results of the ex- 

 amination of several methods that have 

 been employed for the purpose mentioned. 

 It was found that the Sjerining method, 

 employing a solution of tannin and sodium 

 chloride, gave the most satisfactory results, 

 but much better results could be secured 

 by increasing the amount of both tannin 

 and sodium chloride in the reagent. The 

 maximum results were obtained when the 

 proteid bodies were precipitated in a solu- 

 tion containing 15 grams of sodium chlo- 

 ride and 5 grams of tannin per 100 c.c. 



The claim of earlier writers that an ex- 

 cess of tannin has a solvent effect on the 

 precipitate was not confirmed, although 

 solutions containing 7.5 grams of tannin 

 per 100 c.c. were employed. It was found 

 that when the precipitation and filtration 

 were conducted at from 12° to 15° C. much 

 more satisfactory results were obtained, 

 and clear filtrations were much more readily 

 secured than in the case of room tempera- 

 ture. 



Attention is called to the fact that the 

 precipitating power of various prepara- 

 tions of tannin is not quite uniform, and it 

 is suggested that a uniform tannin be used 

 in the prosecution of any particular in- 

 vestigation. It is also essential that correc- 

 tion be made for the nitrogen content of 

 the tannin employed as reagent and that 

 blanks be run with the reagent in order to 

 determine the amount of nitrogen precipi- 

 tated from the tannin of the tannin-salt so- 

 lution. Attention is called to the fact that 

 tannin undergoes fermentation and loses to 

 a large extent its power of precipitating 

 proteids. The reagent should, therefore, 

 be kept in a cool place and for not more 

 than a few days at a time. 



The effect on a number of amido bodies 

 of a solution containing 15 grams of sodium 

 cMoride and 5 grams of tannin was also 

 studied. No precipitation was obtained 

 with glyeocoll, alanine, glutamic acid, as- 

 partic acid, allantoin, asparagine, betaine, 

 creatinine, glutamine, guanine, xanthine, 

 hypoxanthine, leucine, diphenylamine, acet- 

 amide and sarcosine. Precipitates were 

 obtained with creatine, trimethylamine and 

 phenylenediamine. It is probable that 

 phenylenediamine and trimethylamine do 

 not occur in meat, but the latter is found 

 in considerable quantity in fish and in beet 

 root. The error occasioned by the partial 

 precipitation of creatine may be corrected 

 by determining creatine, before and after 

 the precipitation with the tannin salt solu- 

 tion, by means of Folin's method for the 

 estimation of creatine in urine. 



The Influence of Salicylic Acid on the 



■Excretion of Urea and Uric Acid, and a 



Comparison of the Mdrner-8 jiqvost and 



Braunstein Methods for Determining 



Urea: F. C. Webek. 



The Influence exerted by Chemical and 

 Physical Agents on the Yirulence and 

 Speed of Development of Mouse Tumors : 

 G. H. Ct,owes. 



The Effect of the Rays of Radium on 



Plants: C. S. Gager. 



Experiments of the writer show that the 

 rays of radium and of other radioactive 

 substances, such as radio-tellurium and 

 thorium, act as a stimulus to the various 

 life processes of plants. There are doubt- 

 less minimum, optimum and maximum 

 points, depending upon the strength of the 

 radium preparation, the distance and time 

 of exposure, and the intervention of sub- 

 stances more or less opaque to the various 

 rays. The quantitative determination of 

 these points has not yet been made. 



"VVTien seeds, either dry, or during the 

 imbibition of water, are exposed to radium 



