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JOURNAL OF CHEMICAL EDUCATION
periodic system, he ended each period with an inert gas, just as most modern authors do. Then, in order to be able to have 2 periods each of 2, 8, 18, and 32 elements, he postulated the existence of two elements, "coronium" and "nebulium" (for which spectral lines were thought to exist), having positions between hydrogen and helium (previous reference, p. 12). As a result, his "ordinal numbers" did not agree with Moseley's atomic numbers-Rydberg's were all, except in the case of hydrogen, two units too large. In the article which is much cited as the supposed source of the so-called Rydberg series, Rydberg concludes: "In the complete coincidence of the order of Mr. Moseley's numbers and of my ordinals of the elements, I see a very strong support of my system, accordmg to which there should be respectively 4, 16, 36, and 64 elements in the first four groups. But then we shall also get my ordinals instead of the numbers used by Mr. Moseley." Who, then, originated the "Rydberg" series? We have thus seen that Rydberg deserves a good deal more credit than he is given, though he apparently does not deserve some that he is given. (Textbook authors, please note!). In view of the original reason for this communication, it should be added that Rydberg's system was not accepted because of the seeming evidence against a second rare-earth series in the seventh period (the eighth in Rydberg's table) (SODDY, F., Ann Rpts., 13,254 (1916)). I t is of interest to note that Charles Janet, in 1928, published a periodic table incorporating Rydberg's quadratic groupings with the van den Broek-Moseley atomic numbers ("La Classification HBlicoidale des Elements Chimiques," Fascicle No. 4, Imprimerie DBpartmentale de I'Oise, Beauvais, France, Nov., 1928; Chem. News, 138, 372, 388 (1929)). Janet's efforts have also gone unappreciated until quite recently.
(2) Relief from the boredom of repetitious test tube quality tests in L'goose-step" with the rest of the class. I n synthesis there is something created in weighable amounts. (3) Synthesis in process often induces self-initiated procedures that challange the performer's resourcefulness. (4) Motivated library search with the expectation that the results of the search are to be shared by the next generation of students working upon inorganic preparations. (5) Such experiments permit both the student and the teacher to evaluate their success. Both the quality and quantity of the yield testify to the technique and other skills of the experimenter. The writer used a somewhat different plan in the use of inorganic preparations from that described by Dr. Holtzclaw. He restricted the assignment to members of his class who had attained an upper-quartile rank in the general chemistry class. Such a student was invited to substitute "preps" for certain of the routine "test tube experiments." If that student accepted such an assignment he retired to the library and found and prepared two diierent patterns for the preparation he had chosen. He made an oral report of these two plans to his laboratory assistant and indicated one he had decided to try. In this report he was expected t o defend his choice under the criticism of his assistant. The completed report on the experiment included: 1. Presentation of a carefully weighed and packaged total of the preparation. 2. A written report including: (a) Quantities and character of the raw materials used; ( 6 ) listing and brief exposition of specific reaction controls involved in the preparation; (c) reactions. i. e . , equations, with computations of the theoretical yield and the oercentsee of it actuallv obtained ,: (d) . . self-criticismof techniaues used and suezestions for imorovement: and (el . . at least one new rrfvr~nreulmn ;r slnndard 3- X &in. lilmry card for srlrlnion to thr Frrrhnnn Inorganic Prcpw3rions Ilihliugraphy krpt i n the department library, ~~~
REINOW. HAKALA S Y ~ A C U UNIVERSITY BE SYRACUSE, NEIVYORK
To the Editor: Doctor Henry F. Holtzclaw, Jr.'s, article (February freshman On "Laboratory synthesis in chemistry" merits comment. The following values of synthesis in the laboratory, implicit in his paper, warrant more explicit emphasis: (1) Successful use of principles of chemistry rather than merely instruction about them.
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The writer found that his students seemed to experience quite as much of a lift in preparing such familiar as alums, bleaching powder, or sodium bicarbonate as in attempting to prepare the newer, less well-known substances such as "aluminates," "oxalato ferrates," or complex "cobalto" or "cobalti" compounds.
B. CLIFFORD HENDRICKS LONGVIEW, WASHINGTON
