. Elementary chemical microscopy. Microscopy; Microchemistry. HANDLING SMALL AMOUNTS OF MATERIAL: DISTILLATION 293 thumb and forefinger, place a cooling drop of water upon the top of the slide and heat the watch glass gently over a micro-flame (Fig. 152) until vapors begin to con- dense upon the object slide. Heating to violent boiling must be avoided. The cooling drop upon the upper sur- face of the object slide is removed, the slide raised from the watch glass and turned over with a quick move- ment. The proper reagents for dis- FlG- T52 closing the presence of the constituent being sought a
. Elementary chemical microscopy. Microscopy; Microchemistry. HANDLING SMALL AMOUNTS OF MATERIAL: DISTILLATION 293 thumb and forefinger, place a cooling drop of water upon the top of the slide and heat the watch glass gently over a micro-flame (Fig. 152) until vapors begin to con- dense upon the object slide. Heating to violent boiling must be avoided. The cooling drop upon the upper sur- face of the object slide is removed, the slide raised from the watch glass and turned over with a quick move- ment. The proper reagents for dis- FlG- T52 closing the presence of the constituent being sought are added and the resulting preparation examined with the microscope. The method just described is applicable only to easily vola- tilized substances and where prolonged heating is unnecessary, but even in expelling ammonia, the fingers become uncomfort- ably hot. To avoid this discomfort the distilling device shown in Figs. 153 and 154 may be employed. It consists of a tiny glass . Watch-glass Method of Fio. 153. Apparatus for Microchemical Distillations. (Slightly Enlarged.) crucible C, whose upper edge is ground smooth and true, a sup- porting clamp made of spring brass wire W and an ordinary short object slide O. The component parts arc shown in Fig. 154, and the apparatus in use in Fig. 153. Just as in the watch glass method fibrous asbestos or glass wool is employed as an absorbent, an acidulated or alkaline drop serves to retain the volatile constituent and a cooling drop is placed upon the upper surface of the condensing slide. A lever L serves to keep the. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Chamot, Emile Monnin, 1868-1950. New York, Wiley
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