358 



SCIENCE 



[Vol. LV, No. 1423 



stronger or weaker than another, or a certain 

 salt to be more hydrolyzed than another; what 

 properties of substances make them useful for 

 certain purposes. 



The success with which the more intelligent 

 students are able to answer such questions has 

 convinced us of the efficacy of this form of 

 instruction. The students seem also to grasp 

 something of the enthusiasm and interest in 

 the science of chemistry which turns some of 

 them ultimately into capable research workers. 

 We have noted with considerable satisfaction 

 moreover, that even the more purely descrip- 

 tive type of chemistry is rather readily learned. 

 It is evident that the habit of correlating facts 

 with each other and with theory has made the 

 assimilation of the information comparatively 

 easy. 



In order to achieve its object such a course 

 must have the advantage of contact with the 

 more advanced work and the research carried 

 on in the department, and must be taught by 

 men interested in discovery. It has been our 

 policy, therefore, for all members of the de- 

 partmental staff to take part at more less fre- 

 quent intervals not only in the weekly confer- 

 ences of instructors, but also in the laboratory 

 and quiz sections. This practice has been ef- 

 fective in unifying the purposes of all the de- 

 partmental courses. The junior assistants are 

 all candidates for the Ph. D. degi-ee, and hence 

 actively engaged in research. The better stu- 

 dents are frequently invited to see the work 

 these graduate assistants are carrying on in the 

 research laboratory, which proves a source of 

 considerable inspiration. 



Thus beginning with students from the high 

 school, many of whom have not had even high 

 school chemistry (for we admit students if they 

 have had high school physics and trigonometry ) , 

 we are able to accomplish in a single intensive 

 course what is ordinarily extended over two 

 years; and by continuing the same intensive 

 method in the more advanced courses, to pre- 

 pare the student for serious I'eseareh at the 

 beginning of the senior year. The large pro- 

 portion of students who go on into gi-aduate 

 work and the output of the laboratory in re- 

 search are evidence of the rich fruit of the 



method. We are confident also that those stu- 

 dents who have studied elementai-y chemistry 

 as preparation for some allied science have 

 received a far better training for their later 

 work than a more purely informational course 

 could afford. 



Joel H. Hildebeand 



ARE IODIDES FOODS? 



It has been considered by some biologists 

 and chemists that living matter originated in 

 the sea and the elements of living matter cor- 

 respond to those found in the sea water. We 

 might look, therefore, to the composition of 

 sea water for the elements we should expect to 

 find in living matter. Sea water consists 

 largely of H.,0 and sodium chloride, and be- 

 sides those the chief ingredients are magne- 

 sium, calcium, potassium and carbonates, sul- 

 phates and bromides, but there are also present 

 the following elements in traces : ammonia, 

 lithium, rubidium, caesium, strontium, barium, 

 manganese, zinc, iron, cobalt, nickel, lead, 

 copper, silver, gold, radium, fluorine, iodine, 

 nitrate, phosphate, silicate, aluminium, boron 

 and arsenic. In searching for these substances 

 in living tissue they have been found chiefly in 

 marine organisms. However, chemists are 

 finding them to a greater and greater extent in 

 tissues of mammals. Damiens^ finds bromine 

 in a large number of animals and Gautier- 

 finds iodine in quite a number of animals. We 

 are familiar with the fact that fluorine is a 

 regular constituent of bones and teeth and 

 iodine of the thyroid gland. In experiments 

 on the nutrition of animals, I have found it 

 very convenient to feed them evaporated sea 

 water and in this way insure a supply of all 

 the rare elements. Cameron and CarmichaeP 

 have not observed any deleterious effect in 

 feeding rather large doses of sodium iodide to 

 white rats and rabbits. The use of sodium 



1 Damiens, A., Comptes Sendus, 1920, elvvi : 930. 

 Damiens, A., Bull. Soc. Chem. Biol., 1921, 

 ill: 95. 



■ = Gautier, A., Comptes Eendus, 1920, clxx: 261; 

 1899, exxix: 66. 



3 Cameron and Carmichael, J., Journal of Bio- 

 logical Chemistry, 1920, slv: 69. 



