JULY, 1947
THE GENERAL CHEMISTRY LABORATORY1 JOHN C. BAILAR, JR. University of Illinois, Urbana, Illinois
ONE FACTOR in the high cost of teaching physiial science is the inefficiencyin the utilization of laboratory space. I n the typical arrangement of a chemical laboratory, each student is assigned a drawer, below which is a cupboard, the width of this unit varying from 20 to 26 inches. Three of these constitute one " working space," so that each student has about six feet of desk space. Thus, three students use the same desk space during the course of a week. In some of the advanced courses, the shdents may be in the laboratory as much as nine hours a week, but in general chemistry the students are hardly ever expected to spend more than six hours a week in the laboratory so the room is used only 18 hours during the week. This has proved in many colleges to be a major obstacle in obtaining funds for new laboratory space. It is only natural for the dean or the president to ask, "How is it that you need more space when your present laboratory is in use less than half of the working day?" As far as general chemistry is concerned, this problem of inefficient use of space was met and overcome at the Universitp of Illinois in 1930 when the Chemistry Annex was designed. A careful analysis of the experiments in general chemistry and qualitative analysis showed that the pieces of apparatus which the student lockers then contained could be readily divided into three groups: (1)Simple, common equipment that is used frequently and that may be lost or broken easily (flasks, test tubes, beakers, forceps, files, and matches, for example). There seems no alternative but to give the student a locker in which to keep this equipment. (2) Other equipment which is used frequently but which is not apt to he lost or broken (funnel stands, suonges, These things . - . ring- stands, and rings). - . - can be
left o i the desk top for the common use of a11 the students who are assigned to that working space. (3) Equipment which is used only once or twice during the course (thermometers and lead dishes for use in making hydrofluoric acid). This group may also include some common glassware. For example, there are many experiments in which a 250-ml. flask is used. If there are one or two experiments during the semester that require the use of two such flasks, the second flask will fall in group (3) of this classification. Apparatus of this sort should not be kept in the student lockers, but in the storeroom where i t can be obtained on temporary loan as needed.' We have -found that this not only saves space in the student's locker, but decreases the breakage on these seldom-used items. It was found that all of the items in group (1) can easily and conveniently be stored in a locker 16 inches wide, 15 inches long, and 9 inches deep. These lockers were built in the form of drawers, three horizontal rows of three drawers each per working space. This arrangement has proved to he entirely satisfactory for our purposes. Our students in general chemistry meet in laboratory either two, four, or six hours a week, depending upon curriculum and previous preparation, and by careful planning of schedules we are now actually using one laboratory 44 hours per week, each working space being occupied by nine different students during the week. A decimal system of numbering these lockers was adopted, there being no lockers with numbers ending in the digit "0." The nine lockers under each working space are numbered so that the one in the upper left-hand corner ends in "1," the one next to it in "2," and so on. The members of a given class are all assigned lockers with numbers ending in the same digit. This has greatly simplified the assignment of laboratory space. 1 Presented before the Division of Chemical Education a t the Many smaller colleges do not have enough students 111th meeting of the American Chemical Society in Atlentio city, in general chemistry to adopt this plan in its entirety. April 14-18, 1947. l'
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However, it may easily be modified to suit local needs. For example, a vertical column of three such lockers as I have described and two of the conventional drawercupboard units can make up one working space. The laboratory then might accommodate a section of organic chemistry, a section of quantitative analysis; and three sections of general chemisty. Such units will have to be made to order, but this additonal cost, spread over the 40 or 50 years of the life of the building, will be much less than that involved in giving each student in general chemistry three times as much locker space as he needs. If possible, individual hoods should be installed on each working space. While these cost more than a few large hoods, their use greatly increases the efficiency of the laboratory, as it obviates the need for the student to leave his desk to use the hood. Hoods 15 inches wide and 21 inches high easily accommodate the apparatus used in general chemistry and qualitative analysis, but cannot well be used for organic chemistry. Unfortunately, the selection of the proper material of construction for such hoods has not yet been solved satisfactorily; alberene is heavy and costly, wood chars readily, metals corrode, and transite cannot stand the strong acid'fumes. The best solution which we have found involves the use of cast metal which is frequently painted with a heavy, heat-resistant paint. The vents from the hoods should be carried down through the floor into a common duct on the ceiling of the room below. This leaves the room free from unsightly pipes and greatly facilitates the lighting of the laboratory. Each desk should be provided with water and gas, and if individual hoods are used, hydrogen sulfide should be piped to each desk. For the few experiments requiring suction, vacuhm lines may be run to the desks or aspirating pumps may be provided. If individual hoods cannot be installed, the laboratory should be provided with several large hoods along the wall (at least one six-foot hood for every 12 students). These should have outlets for water, gas, and HS. It is more convenient and cleaner to buy hydrogen sulfide in cylinders than to generate it as needed. ' It can be run from the cylinder into a gasometer floating in oil, and thence piped to the laboratories. The cylinder and gasometer should not be housed inside the building, as the valves sometimes stick and allow gas to escape. Unless the architect has had experience in ventilating chemical laboratories, he is almost sure to underestimate the volume of air needed. This should be a t least twice the amount needed to ventilate classrooms or offices. A good deal of this air, or perhaps all of it, can be drawn out through the hoods. The cleanliness of the laboratory and the comfort of those who work in it are greatly increased by adequate ventilation, and the problems of corrosion are greatly decreased. If the laboratory periods do not exceed three hours in length, the students in the laboratory should stand. We have found that students who sit to do their labora-
JOURNAL OF CHEMICAL EDUCATION tory work accomplish much less than those who stand. Moreover, stools clutter the laboratory and necessitate the use of wider aisles between the desks. If the stuents are to stand, five feet between desks is sufficient, while six feet is required if stools are used. Each laboratory should be provided with a distilled water tap and with outlets for direct and alternating current. The direct current is required only for experiments on ionization and electrolysis, so two or three outlets are enough for a class.' This d. c. can conveniently be 110 volts, although smaller voltages can be used. The alternating current is needed to operate the centrifuges which are now so widely used in qualitative analysis. One centrifuge should be provided for each 12 students. At our school, as a t many others, the laboratory rooms are large enough to accommodate several sections a t one time. Other schools have felt that each class should have a room to itself. Undoubtedly, this latter system has advantages, but it is our opinipn that several sections can work together in one large room without interfering with each other if certain conditions are met: (1) The aisles must be wide enough to allow free passage of the larger number of students-ten feet if the room is built to accommodate 100 students. (2) Lighting over the whole area must be good. (3) Blackboard and side-shelf facilities must be equally available to a11 classes using the room. (4) The acoustics of the room must be such that the classes do not disturb each pther. A teacher must be able to give his pupils a demonstration or a blackboard talk without interrupting the work of the other sections. This problem is not as serious as it may seem, for most teachers prefer to gather their students into a rather compact group for such discussions. However, it is necessary that the room be given some acoustical treatment if 80 or 100 students, in four different classes, are to use it simultaneously. I do not mean to imply by this that a laboratory for a single class should not have acoustical treatment. This is a factor in laboratory design which has been sadly neglected and which should receive consideration in the design of any laboratory space. It is not expensive if done in constmetion (as by building of cinder block); it is expensive later. The practice of having several classes in the laboratory simultaneously has some positive advantages; for example, it allows two or three inexperienced teachers to work under the eye of an older person. On the other hand, it increases the cost of ventilation, as the whole room must be ventilated, even if only a part is used. Naturally, the storeroom and the balance room should be as close to the laboratory as possible, but they should not open directly into it. There is always conversation and a little confusion at the door of the storeropm where apparatus and unknowns are issued to the students; this should be kept out of the laboratory. The balance room should be separated from the laboratory because even in well-ventilated laboratories there are apt to be corrosive fumes.
