chemistry are put into the same course in college it is not a case of those without high-school chemistry catching up, it is a plain case of keeping those back who entered with high-school chemistry. I am quite certain that I was the first one, out here anyway, who separated the two groups and treated those who had had high-school chemistry as if their one hundred eighty hours of high-school chemistry had meant something to them. I have never regretted it. What I contend is that the college first-year course does not stand on its own feet-it stands on the toes of the high-school course. The high-school course does not need to copy a college course; the textbook writers have seen to that and so successful has been their effort that the books are all but idatical. As for the statistics, they are not lies at all-they are too cruelly and graphically true. Chemistry has stood still for forty yearssomething must be the matter. I insist that my suggestion is not only real chemistry, but realistic chemistry; a course that will teach the ninety-eight per cent. of our young people who do not go into scientific pursuits what chemistry is, what it does, and its glorious history. When a course in highschool chemistry or physics in your town makes it necessary for the salesmen and merchants of the community to go to school to study the articles of their trade so as to be prepared to meet the skilful .scmtiny of the boys and girls of the homes, that comes near being a case of putting high-school science on the map. That's what happened in St. Cloud, Minnesota. Merchants and salesmen have had to study in self-defense to meet the intelligent questions and arguments of their prospective customers. This idea that you are giving the class a substitute or that you are putting something over on them by teaching them what is useful, what they will never forget, instead of thousands of facts to be forgotten next year, is the old argument of fifty years ago which had to be fought out before chemistry was allowed in the curriculum a t all. P The person who is not teaching high-school chemistry as a glorified general science is out of step by fifty years --chemistry is the General Sciace: it underlies every scienceand that means it forms the basis of all life. Let us make high-school chemistry a Glorified General Science Course with a capital G. I t is interesting that several letters commending my article came from the bailiwick of the College Entrance Examination Board and the Regents of the State of New York. P. M. GLASOE ST. O M COLLEGE N O R T ~ E LMmmso'rn D,
To the Editor DEARSIR: I thoroughly enjoyed Professor Glasoe's article in the January issue on "A High-School Course in Chemistry
Which Does Not Lead to Repetition in College." With most of his points I agreed heartily. However, in his suggestions for the new procedure, on page 14, I feel that his example of the sort of thing to teach in the high-school chemistry course was not well chosen-it is doubtful in my mind whether a detailed, lengthy study of the Weather Bureau, high and low pressure areas, trade winds, tornadoes, whirlwinds, and so forth, is appropriate for the chemistry course. Since no chemistry is involved in that subject, it should be given in general science, physics, or meteorology (geography), and a better example for Professor Glasoe's purpose would have been something dealing with chemistry and chemical changes. GRANTW. SMITH Tm UNIVERSITY OF KANSAS CITY CITY, MISSO~
"MNEMONIC DEVICES IN CHEMISTRY" To the Editor DEARSnz: I read with interest Lieutenant Bermingham's article, "Mnemonic Devices in Chemistry" (J. CKEM. Enuc., 16, 516 (1939)). I would like to call yow attention to another interesting mnemonic device which I have found quite useful. I t is, "Oh my, such good apple pie, sweet as sugar." The initial letters of these words comprise in orde.: the initial letters of the names of t4e saturated aliphatic dibasic acids. This device is not original with me, but was passed on to me several years ago by a student from the Massachusetts Institute of Technology. How- M. TEETER
"FLUORSPAR-ITS CHEMICAL AND INDUSTRIAL APPLICATIONS" T p the Editor DEARSIR: In my article, "Fluorspar-Its Chemical and Industrial Applications," in the April issue of the JOURNAL I failed to give credit to Martin Schwerin for the ideas embodied in the following sentences. "The deposit operated by Victory Fluorspar Mining Company is a replacement of the limestone, the banding of the ore, typically illustrated in Figure 3, being a relict structure due to physical and chemical differences in the layers of the original limestone resulting from seasonal changes while it was being laid down. The comb structure of pure bands is due to a decrease of volume, the CaF2 molecule being more dense than the CaCOa molecule which is replaced."
The geology of the deposit was covered by him in an article entitled "An Unusual Fluorspar Deposit" published in the Engineering and Mining Journal, for September, 1928. LENHERSCHWERIN VIcronv FLUORSPAR MININGCOMPANY EL~AEETRTOWN, ILLINOIS
OBJECTIVE TESTS IN ORGANIC CHEMISTRY The 1940-1941 Series of the Cooperative Objective Tests in Organic Chemistry are now in the process of preparation. It is believed that the present series will meet the need of the average instructor of organic chemistry somewhat better than any of the tests of this series thus far prepared. It is hoped, furthermore, that those who elect to use these tests during the coming school year will cooperate with us to the extent that this series may be standardized and the validity of each item determined. One page is devoted t o each of twenty-six topic examinations in organic chemistry, and three pages each to the final examinations for the t i r t and second semesters, making a total of thirty-two mimeographed pages to a set. These sets are available to instkctors and graduate students or research workers in lots of five or more a t twenty cents each. Single sets are thirty-five cents. Those using these tests in their classes will be provided with a key for convenience in grading. Anyone who is interested in examining or using the 1940-1941 Series of Cooperative Objective Tests in Organic Chemistry may place his order with Ed. F. Degering, Chairman, Cooperative Objective Tests in Organic Chemistry, Purdue University, Lafayette, Indiana. Ep. F. DEGERING P ~ U UNIVERSITY E LAFAYETTE. INDIANA
"THE EFFECT OF THE NATURE OF THE COURSE ON ACHIEVEMENT IN FIRST-YEAR COLLEGE CHEMISTRY" To the Editor DEARSIR: Clark might be able to philosophize upon the socalled "conclusion-inevitable" that he makes in the article entitled, "The Effect of *Nature of the Course on Achievement in First-Year College Chemistry,"' but no statistician or scientist would allow him to base his conclusions upon the numerical gymnastics that he
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C-, "The effect of the nature of the course on achievement in first-year college chemistry," J. C m . EDUC.,16,510-11 (Nov.. 1939).
describes. Of course, it is possible that the experimenter may have made many other computations without bothering to record them in his paper. Certain additional data could certainly prove useful, but this critic will naturally have to assume that all of Clark's work is described in the report. Little does Clark apparently realize how correct he actually is when he says, "Perhaps the reader should be cautioned against indiscriminately applying the above conclusions to other groups of students." (1) Clark attempts to compare the gains made by students in the elementary group and the advanced group by determinimg their "average gain". He obtains this gain by "end-test percentile minus pre-test percentile." By chance, the particular groups with which he was dealing (those having had high-school chemistry credit) actually increased their percentile ranks, thereby allowing him to ohtain positive numbers rather than negative ones. Percentile ranks are similar to rank order in which i t is easy to understand that a class of seventy-five must have seventy-five rank orders represented hoth in the pretest and in the end-test. The various changes both plus and minus that occur must always become equal to zero algebraically. A person holding his own must actually be gaining in true score and achievement if the class as a whole is learning anything. If a group, as was the case here, actually gains in rank order or percentile, it merely means that they are somewhat more select in their rate of increase than the others in that same group. Clark compares these rates of gains with the rates of gains of another group that apparently has not been equated in any way. These figures are meaningless arid misleading. (2) Clark'finds a correlation of 0.88 between the pre-test and end-test percentiles for the control group (elementary chemistry). In the 6rst place, percentiles represent a rectilinear distribution rather than a frequency distribution which might,be more similar to the normal curve. Equations for computing correlation are not designed for rectilinear distributions and therefore the data are less meaningful than might be supposed. (3) However, after finding this correlation of 0.88, Clark sets up a regression (for this elementary group) and gives i t as
XI
=
0.98 Xs f 17.12
With this, he can predict the end-test ranks from those on the pre-test. Accordingly, "end-test percentiles were then predicted for all members of the control group and a correlation of 0.88 was actually found between the predicted and the earned values." All Clark seems to have proved by this useless manipulation is that his arithmetic has apparently been correct both times and that the old truth, things equal to the same thing are equal to each other, is still as true as ever. (4) "By means of this same regression equation," for the clark then predicted the end-test students in the advanced group. The real meaning of
