VOL. 6, No. 2 COURSE POR VARIATIONS on LEARNWG CAPACITIES 331

met with either in the laboratory or in life. The course is made as practical as possible. Emphasis is placed on such things as purification of water, softening of water, combustion, iron and steel, etc., rather than on prepara- tion for higher chemistry.

It is realized that this differentiation is hased on the ability of the students of various learning abilities to achieve the results under the present method of instruction. It is assumed that students of low IB do not go to college in numbers, while most of the high IB students go to college.

The following questions have not been investigated, but plans are being laid to attack them:

1. What percentage of slow students go to college? What percentage of fast students go to college? If considerable numbers of slow students go to college, then what change in the chemistry course should be made?

2. What modifications in procedure of instruction should be made for the different groups?

Ultraviolet Light Stronger in Country. The amount of ultraviolet light in the country is actually half again as great as in the city. This has been known or suspected in a general way for some time, but now scientific proof of i t has been made by J. H. Shrader. M. H. Cohlentz, and F. A. KorK. working a t the Baltimore department of Health. The figure reported is the result of actual measurements hased on chemical tests. They were made in the center of the city, in nearhy suburbs located about three miles from the city's center, and in the country on farms ten miles from the municipal center.

Measurements of the amounts of dust polluting the air were made a t the same spots. These showed that air pollution affects the amount of ultraviolet light. The pollution was heaviest in the city and diminished to a figure about one-sixth as great in the country. The amount of dust settled on the top of skyscrapers was less than the amount at the street level, and the amount of ultraviolet light on the top of the buildings was greater than that a t street level.

The kinds of dust polluting the air were examined. Carbon, in the form of tarry products, kept out more of the ultraviolet light than ordinary dust or street sweepings.- Science Service

Drugs Need Protection from Light Rays. Light which is so helpful to sick persons does not do their medicines any good. In fact so many of these deteriorate upon ex- posure t o light that druggists have authorized a special study t o discover containers which will protect their medicines and chemicals from the harmful light. The plans uf the rommirtec which is ondcrtnking the rtudy were reported recrotly to the American A~sorintion for the Advanccrncnt oi Srirnce by 11. V. Amy of Cnluml~ia Ilnivcrstty, head of the committee which was formed by the American Pharmaceutical Association.

In same cases light rays seem t o preserve the medical virtues of a preparation, but in others they are definitely harmful.. The changes which patients notice in the colors of medicines is usually indicative of change in the medical properties. The follow- ing are among the changes, said Dr. Amy. The green color of some iron preparations changes to an unpleasant brown. Bright yellow ointments turn brown or green. Tinc- tures and fluid extracts made from vegetable drugs turn a dark color and deposit sedi- ments. Serums and other biological products lose their ability to cure or prevent dk- ease.-Science Senrice