1016 



SCIENCE. 



[N. S. Vol. XV. No. 391. 



The ' Thiosulphate Method' of Measur- 

 ing the Bate of Oxidation of Iodides: 

 Mr. J. M. Bell. 



The method was introduced by Har- 

 court, using sodium peroxide as oxidizing 

 agent; it is not applicable when chloric 

 acid, chromic acid, or ferric salts are em- 

 ployed. Schiikarew's assumptions (Zeit. 

 Phys. Chem., XXXVIII., 357) are not 

 justifiable. W. Lash Miller, 



Secretary pro tern. 



PROBLEMS IN THE CHEMISTRY AND TOXI- 

 COLOGY OF PLANT SUBSTANCES.* 



The organic chemistry of to-day is the 

 chemistry of the approximately 50,000 car- 

 bon compounds, enumerated in the recent 

 edition of Beilstein's 'Handbuch der Or- 

 ganischen Chemie.' Most of these com- 

 pounds are the fruit of research in purely 

 synthetic chemistry, enormously stimu- 

 lated, as it has been of late, by the growth 

 of new, far-reaching conceptions in phys- 

 ical chemistry, and, especially, by the sub- 

 stantial rewards of the chemical industries 

 which have arisen as a result of these in- 

 vestigations ; a considerable number of the 

 compounds enumerated have, however, been 

 isolated from plants. Some of this work 

 of plant investigation has been adequately 

 rewarded, but as a rule it has only awak- 

 ened a greater esteem for the investigator. 

 The larger returns of synthetic chemistry 

 -are still enticing most of our best organic 

 chemists into its fold, but its phenomenal 

 success in producing substances such as 

 urea, sugar and several plant alkaloids and 

 glucosides hitherto known only as the prod- 

 ucts or educts of life, has stimulated inquirj^ 

 not only into the chemical nature of cell life, 

 but also into the chemistry of the dead 

 principles that may be isolated from these 

 cells. Mother Nature is, however, a very 

 cunning and crafty chemist, with a keen 



* Address of the retiring president of the Chem- 

 ical Society of Washington, April 10, 1902. 



understanding of all of the requirements 

 of cell growth under astonishingly varied 

 conditions of environment, and especially 

 with an eye for the protection and perpet- 

 uation of her multitudinous progeny 

 against the ravages of parasites, or of man 

 and beast, she has built up a very great 

 variety of compounds, the properties and 

 methods of formation of many of which 

 she still holds secret. Many of these com- 

 pounds, especially those primarily designed 

 for the protection of the plant, react phys- 

 iologically on diverse forms of animal life, 

 and are, therefore, recognized by the med- 

 ical fraternity and by chemists as 'active 

 principles.' All which produce disturb- 

 ances of the normal functions of an animal 

 when introduced into its economy are, ac- 

 cording to Hermann's well-known text- 

 book on pharmacology, called poisons. 



It is a sad commentary on the present 

 state of our knowledge of plant chemistry 

 that all we know chemically about the 

 active principles of many plants is 

 that the plants themselves are poison- 

 ous. Chemistry might be excused for 

 her lack of interest in examining such 

 physiologically-inert bodies as cellulose and 

 chlorophyll, but it would seem that the 

 plant poisons should at once challenge at- 

 tention simply on account of their great 

 tendency to react chemically, as they do 

 with some one or more of the essential con- 

 stituents of the animal organism. The 

 dreaded effects upon man of such plants as 

 the 'deadly upas,' the 'deadly manchineel,' 

 or the common 'poison ivy,' deter many 

 chemists from handling them, and, as shown 

 above, there is little inducement finan- 

 cially for one to enter into such investiga- 

 tions, but the chemist's lack of a knowl- 

 edge of botany is more frequently the con- 

 trolling factor in this neglect. Many of the 

 most interesting problems of plant poison- 

 ing cannot be conceived either by the chem- 

 ist or by the botanist alone, but one who is 



