Mat 15, 1908] 



SCIENCE 



775 



posed? The physico-chemical method of 

 investigation shown here easily leads to a 

 correct analysis of the action; as a matter 

 of fact, we find silver nitrate a far more 

 powerful oxidizing agent than is ammo- 

 niaeal silver oxide, and it is so because in 

 both cases the oxidation is due to the tend- 

 ency of the silver ions to discharge their 

 positive electricity and that positive elec- 

 tricity is the real oxidizing agent here just 

 as it is at the positive pole in every case 

 where a current is passed through any solu- 

 tion whatever. In the silver-nitrate solu- 

 tion there is a far greater concentration 

 of these discharging silver ions than in the 

 ammoniacal solution, in which most of the 

 silver is present in the rather stable com- 

 plex ion, [Ag(NH3)2]. But the alkali is 

 used to increase the concentration of the 

 active reducing component of the alde- 

 hyde—which probably is a methylene salt 

 ± CH(ONa) or its ion=— the alkali added 

 to the silver nitrate is positively detri- 

 mental to the latter 's oxidizing power. 

 (Illustrated by an experiment with silver 

 nitrate against formaldehyde and sodium 

 nitrate; then alkali is added to the alde- 

 ^ The oxidation of an aldehyde is best inter- 

 preted as being due to the oxidation of sodium 

 oxymethylene (NaO)CH±, the two free valences 

 of which may justly be considered to consist of a 

 positive and a negative electric charge. Any oxi- 

 dizing agent, e. g., the positive current of elec- 

 tricity resulting from the discharge of the silver 

 ions, would oxidize this as follows: 



(NaOCH) ± and 2 positive charges — > (NaO) CH + 



and the hydroxyl ions of the alkaline solution 

 would by uniting with this residue give sodium 

 formate : 



( NaO ) HC ^ -f 26h -^ NaO ( HCO ) + H^O. 



The two sodium ions belonging to the two hy- 

 droxyl ions used migrate to the silver nitrate cell 

 in the chemometer, replacing the two silver ions 

 which have been discharged — all of which corre- 

 sponds to actual observation. (Views developed 

 by Nef, W. A. Noyes and others are in part ap- 

 plied in this interpretation.) 



hyde, and finally ammonia to the silver 

 nitrate.) It could be shown in the same 

 way that the alkali used with Fehling's 

 solution in the oxidation of glucose is used 

 wholly for its action on glucose, and is 

 rather a disadvantage than helpful as far 

 as the copper is concerned. This method 

 of investigation enables us, therefore, to 

 analyze the action of our oxidizing and re- 

 ducing agents, and it promises to lead us. 

 ultimately to a mathematical solution of 

 the problem. 



Julius Stieglitz 

 Univebsity of Chicago 



SCIENTIFIC BOOKS 

 Psychology: General Introduction, pp. 389. 

 Laboratory Manual of Psychology, pp. 127. 

 Laboratory Equipment for Psychological 

 Experiments, pp. 257. By Charles Hub- 

 bard Jddd, Professor of Psychology at Yale 

 University. New York, Charles Scribner's 

 Sons. 1907. 



Professor Judd's contribution to the avail- 

 able facilities for the teaching of psychology- 

 is a notable one. The plan is consistent, the 

 execution capable, the result distinctive. The 

 text becomes part one of the series of three 

 volumes; a brief laboratory manual makes 

 possible the performance of a considerable 

 range of demonstrations and individual ex- 

 periments, all reduced to as simple a material 

 basis as is compatible with convenience; while 

 the third volume furnishes the instructor with 

 a vade mecum for management and equipment 

 of his modest instrumental plant. The gen- 

 eral plan thus provides for the " object lesson " 

 conduct of an introductory course in psychol- 

 ogy, suitable at once to colleges and universi- 

 ties and to normal schools that are ready to 

 give psychology a prominent place in their 

 schedules. The text becomes available alike 

 with such illustrative experimentation and 

 without it, or with such portion of it as 

 meager facilities make possible. 



In distinction from the more conventional 

 text which implies and as a rule receives the 

 supplementary exposition of demonstration, 



