SIMPLE QUARTZ MERCURY-VAPOR LAMPS FOR BIOLOGICAL AND PHOTOCHEMICAL INVESTIGATIONS

Abstract

The quartz mercury-vapor lamps described below were made by the writer for use in connection with some experiments on the biological and chemical effects of ultraviolet light. At the time the lamps were made there were no quartz mercury-vapor lamps on the market in this country. The lamps gave, and are still giving, after four years’ use, excellent results. They are less expensive than any of the commercial lamps known to the writer; and, furthermore, as will be seen, the design of these “home-made” lamps can be altered to suit particular requirements. These lamps are not difficult to make. The quartz must be worked in an oxyhydrogen flame, and the burner must be ad- justed so as to give the highest temperature possible; but the technique required for shaping the lamps is simpler than that required to make an ordinary T-joint in, glass tubing, since the quartz joints do not have to be annealed. A good vacuum pump is required for exhausting the lamp. The greatest difficulty is found in making the seals at the points where the electrodes enter. The literature contains a number of more or less complicated and impractical methods, but the seals described below are easily made and are efficient. It may be cheaper at present to have all the quartz parts of the lamp made at the factory. As stated above, these lamps were made before quartz tubing was being manufactured in this country. Figure 1 shows a simple form which the lamp may take.’ A is a quartz tube 1 cm. in diameter. One end is bent downward