Semimicro Equipment for High-School
and College Chemistry WILLIAM J. SCHILLER and SISTER M. LAWRENCE Mount Mercy College, Pittsburgh, Pennsylvania
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OTWITHSTANDING the emphasis upon smallscale or semimicro methods in commercial and more advanced college laboratories, very little use is being made of them in the high-school and college inorganic field. The authors have utilized the semimicro technic in both of these laboratories and have found it to be highly successful. Directions for the semimicro inorganic laboratory *ere in the main lacking when the work was first begun. Outside of E. C . Grey's book' and that of E. V. Hjort2 there was nothing in this field. Following the pattern described in these foregoing books the authors worked out and had published in lithograph form a laboratory manual for high-school Subsequentl~,with experience garnered from the high-school field, directions were worked out for the college, these being in the m i m e o ~ a ~ form h a t the Present time. In the early stages the student laboratory work was carried out in a laboratory with the ordinary equipment. With plans afoot for a new xience it was decided that the new general chemistry laboratory was to he equipped for semimicro work. The description that follows indicates the design of desks and equipment which they have found successful. In the main the equipment is similar to that used in the regular or macro work but much reduced in size.
Acid-Base Block This contains the concentrated and
acids and alkalies, ~h~ dilute are kept in 35.ml, B~~~~ dropping bottles and the more corrosive in stoppered with ground glass pipets, This block is kept on a special shelf in the cabinet portion of the locker. Each block contains concentrated and dilute solutions of the common acids and alkalies, One of these sets can generally he used by two or more students.
General Clzemical Block This block (Figure 1) contains the chemicals required for experimentation. The solutions are kept in bottles of 8-ml. capacity equipped with bakelite screw caps and small dropping pipets, ~h~ solids are kept in 2ml. fermentation tubes. Extra holes in the block are used as "test tube racks" during the laboratory period. he block is solid, 9" x lo", and drilled to accommodate approximately 40 solutions and 120 solids. One block is used by two students during a laboratory period. A list is also furnished indicating the location of the various materials,
Equi$ment i n Stdent Kit4 1 wire gauze, Cinch 1 beaker, 50-ml. 1 flask, 50-ml. 1 forceps 1 pipe stem triangle 2 test tubes, Cinch fi test tubes. 2-ml. 1 test tube holder 1 buret clamp 4 centrifuge tubes. 3-ml. 4 vials (to collect gases-121 iron ring, 3-inch ml.) 1 spatula, micro 2 microscope slides 2 glass r o d s m a d e by stu1 watch glass, 50-mm. dent 2 dropping pipets-made by 1 graduate cylinder, 10-ml. 1 crucible (Coors 00) student 1 micro funnel 1 crucible cover 1 micro burner 1 funnel brush 1 triangular file 1 wing top GKFY,"l'ractical chemistry by micro mctlrodr," \V. 1Icffw and S m a , Cambridge. lingland. 1925, 134 pp. H loRT A r n \Vurmwmn. "l.at,oratorv dirrctiom in micro inoraanfc chemistry." ~ d w a r d sBrothers, inc., Ann Arbor, Mich.. 1933, 103 pp. SWILLER AND LAWR&NCE, "A laboratory manual for highschool chemistry by semimino methods," Welch Manufacturing Co.. Chicago. 1938, 163 pp. If drawer space is lacking this equipment may be kept in a small-sized box.
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FIGURE 1.-STUDENT
K ~ AND T REAGENT BLOCK
Special reagents are kept in Barnes dropping bottles on a side shelf. Stock solutions are kept in 8-07,. narrow-necked bottles, from which the small 8-ml. hottles in the general chemical block are filled.
General Equifwnent This equipment is kept in the stock room and distributed for student use when needed:
Electrical or hand centrifuges Hand balances with weights Thermometers Dry cells Platinum wire Blowpipe and blowpipe tips Mohr pipets, l-ml. Horseshoe magnets Charcoal blocks
try has been designed and installed in the college. The laboratory is unique in that there are no drain pipes a t the desks; in the reduced size of locker space; in the elimination of fume hoods; and in the addition of chairs permitting the student to sit comfortably during experimentation. Figure 2 shows the construction and arrangement of the desk and equipment. Each desk is equipped with two lead enameled cups, one for solid and one for liquid residue. The liquid residues are emptied into one of two sinks suitably placed in the laboratory. The laboratory, which is 20' by 37', accommodates fourteen tables with space for fifty-six students, or twenty-eight per laborato~yperiod.
Adwantages
Laboratory Furniture A special laboratory for inorganic semimicro chemis-
The semimicro method is to be highly recommended when laboratory space and finances are limited; when it is impossible to give individual equipment; when it is desired to reduce the danger element to a minimum, to have a laboratory free from fumes, to have students seated at their work with all necessary equipment within easy reach; and in general when it is desired to have experimentation carried out with utmost economy of space, time, and materials. Lack of experience on the part of the teacher in the use of the equipment is no drawback because most of it has a counterpart in the regular equipment; facility in its use is readily acquired. The authors will welcome comments or inquiries and will pladlv. extend anv help possible to those besiring added information.
