LABORATORY INSTRUCTION IN GLASS BLOWING ROSS
A. BAKE& COLLEGE O P THE CITY OP NEWYORK, NEWYORKCITY
Same knmledge of glass blowing is adhisable for the student and necessary for the teacher and research worker. The nalue to the undergraduate of the ability to construct apparatus warrants definite instruction i n glass blowing. An introductory course i s outlined.
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The construction of apparatus has been one of the most neglected technics in the American chemical laboratory. Students, progressing normally through the four-year sequence of instruction in chemistry, are usually directed to use highly standardized pieces of equipment without inquiry as to the relative efficiencieseither of the materials of construction or of the characteristic forms in which they are cast. The production of multitudinous shapes and devices by apparatus supply houses is in part responsible for the cookbook attitude of the average student, who may become proficient in assembling conventional set-ups but whose horizon is limited to the stockroom inventory list. The resourcefulness and initiative of the student as well as his actual knowledge of chemistry are notably increased if he is made to feel a responsibility for such laboratory set-ups as will most efficiently serve the reactions he is directed to study. He should choose, if not actually construct, his apparatus and should also keep it in repair. If stimulated to design and make new forms or to vary existing&orms, the student will soon find himself equipped with one of the most valuable of research tools. From the time the freshman first enters the chemical laboratory, the misuse of any piece of apparatus shonld not be tolerated. It is obviously one of the teacher's first duties to instruct his students in the care and use of such standard forms as are to be a t his disposal during the course. He should also make clear the specific limitations and relative advantages of wood, metals, glass, stoneware, porcelain, rubber, and plastics (1). An equally important duty of the laboratory instructor is to give the student a feeling of creative power. If existing or available forms do not seem to serve the purpose in view, the student (and certainly the instructor) shonld be able and eager to make simple effective pieces of apparatus out of appropriate materials. The skills required are usually no more complicated than the cutting, bending, and soldering of metal, the shaping and joining of wood and the manipulation of glass tubing. In final analysis, the apparatus itself is not so important as the student's attitude of mind which leads to its production. While the choice of construction materials is affected by cost, chemical resistance, mechanical strength, thermal qualities, etc., the prime requisite 203
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JOURNAL OF CHEMICAL EDUCATION
FEBRUARY. 1932
for chemical apparatus is transparency. In an experimental laboratoly where unexpected changes must be carefully observed, the substance under investigation should be visible a t all times; if this is of such nature that it must be completely enclosed during the experiment, as is nearly always the case in the chemical laboratorv, then all or part of the container should be transparent. Glass is the only material which combmes transparency with suitable chemical resistance, mechanical strength, low cost, and ease of fabrication. In addition, the fact that glass is a supercooled liquid guarantees a smooth polished surface, inside and out, in the finished product. These advantages far outweigh the limitations imposed by its brittleness and thermal weakness. The conventional courses in general and analytical chemistry include little more glass manipulation than the bending of tubing. Unfortunately, the bends made a t the beginning of the year are usually carefully preserved and used again and again most inappropriately. While the student may learn properly to seal the end of a tube in the organic laboratory and to handle intricate and costly pieces of apparatus in the physical chemical laboratory, his standard method of joining one piece of glass to another is through a rubher stopper or tube. And should he break a glass graduate, distilling flask, or U-tube, his only recourse is to procure another. The instructor contributes his bit by drastically modifying or even omitting experiments for which the prescribed apparatus is lacking. This worship .. at the shrine of ready-to-use apparatus should be abolished for the sake of our future research wnrkrrs. I t is not argued that the chemistry student should spend a n y considerable amount of time makinr pieces of apparatus which can be readily supplied through commercial channels, but it is urged that he learn enough glass blowC m \ ~ a r r c r ~ r rnc T-Tuoe d .
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ing to tide him over emergencies. Only a few basic principles need be taught, with the sole object of enabling the student t o progress independently if necessary. The ability to devise and construct apparatus is even moreessentialfortbeteacher than for the undergraduate student. The responsibility for school exhibits, lecture demonstrations, stockroom devices, and broken apparatus would indeed be a nightmare to one whose only source of T-tubes is an apparatus supply house. The rudiments of glass blowing can be mastered surprisingly well through observation of an experienced operator, followed by supervised practice. A few hours a week for one semester will suffice. If one's only instructor is a printed glass-blowing manual, his mistakes will of course be more frequent and costly. Experience in several universities where glass blowing is taught as a laboratory subject indicates that excellent results are obtained when the instructor demonstrates each operation in advance and also places in the hands of his *students written instructions desaibing the details. The students then prvtice, preferably under supervision, until they have mastered the operation. A beginner should not work before the blow-pipe for more than an hour a t a time and when nervous should by all means postpone his practice period. A recent aid to glass-blowing instruction is the moving picture.* Fundamental technics may be filmed under optimum coqditions and then demonstrated repeatedly, a unit a t a time, while the student C: a is engaged before the blast
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