. The Bell System technical journal . llows that no light canemerge from the condenser if there be a stratum of air above thecondenser. It is therefore necessary to connect the object slidi- .IXD TECHNICAL MICROSCOPY 125 or cell cliamher and tlie top of the contlcnscr by a stratum of immersionfluid free from air bubbles. Cedar oil or pure water is uscti for thispurpose. The chamber for the cardioid condenser is illustrated inFig. 22. The chamber is made of quartz glass and consists of acircular disc having on one side a circular groove and an opticallyplain central portion w
. The Bell System technical journal . llows that no light canemerge from the condenser if there be a stratum of air above thecondenser. It is therefore necessary to connect the object slidi- .IXD TECHNICAL MICROSCOPY 125 or cell cliamher and tlie top of the contlcnscr by a stratum of immersionfluid free from air bubbles. Cedar oil or pure water is uscti for thispurpose. The chamber for the cardioid condenser is illustrated inFig. 22. The chamber is made of quartz glass and consists of acircular disc having on one side a circular groove and an opticallyplain central portion within the groove about 2 n below the planeoutside the grcwve. A drop of the fluid to be examintnl is placedon this depressed central portion and a cover glass of quartz placedover it. The excess fluid is expelled to the annular groove and astratum about 2 /i in thickness is retained in the central portion ofthe chamber for microscopic examination. The cell is assembledin the metal mount which has a clamping ring and a recessed member. Fig. 25—Diagram of the rays in a cardioid condenser. to receive it. The ver>- brilliant illumination resulting from thecardioid condenser would cause glass to fluoresce and for this reasona quartz cell is used. Moreover, glass is more liable to be affectedby corroding agents than is quartz. The utmost care must be taken to prepare the cell chamber. Thisincludes washing with alcohol and water; dipping in boiling sulphuricand chromic acid solution; washing in tap water; rinsing in distilledwater and then in redistilled alcohol; drjing in a hot air current andfinally cooling under a bell jar; all of which is necessary to insureabsolute cleanliness. An automatic arc lamp is used as a source of illumination and theimage of the crater is projected by a projection lens onto the mir-ror of the microscope from which the rays are reflected upward intothe cardioid condenser. 126 BELL SYSTEM TECHNICAL JOURNAL The objecthe used with the cardioid condenser
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Keywords: ., bookcentury1900, bookdecade1920, booksubjecttechnology, bookyear1
