. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . ng the presence of sulphuretted hydro-gen. ment shuts off the gas when 10 cubic feet have passedthrough. The meter employed is shown in figure dial of the meter is divided into 100 parts, andeach complete revolution of the index hand representsthat one cubic foot of gas has passed through theapparatus; and each division, therefore, representsy^Q of a cubic foot. The position of the long index handon the dial must, accordi
. Public health laboratory work, including methods employed in bacteriological research, with special reference to the examination of air, water and food contributed . ng the presence of sulphuretted hydro-gen. ment shuts off the gas when 10 cubic feet have passedthrough. The meter employed is shown in figure dial of the meter is divided into 100 parts, andeach complete revolution of the index hand representsthat one cubic foot of gas has passed through theapparatus; and each division, therefore, representsy^Q of a cubic foot. The position of the long index handon the dial must, accordingly, be carefully noted at thecommencement of each test. 248 LABORATORY WORK. When making the estimation no other gas should beburning in the same room, and, according to the direc-tions of the Referees, the gas (which has been freed fromsulphuretted hydrogen) is to be burnt in a small Bunsenburner mounted upon a short cylindrical stand (figs. 41and 42), perforated with holes for the admission of air(which is necessary to support combustion), and whichhas, on its upper surface, a deep circular channel to re-ceive the wide end of a trumpet-shaped glass tube. On. Fig. 40.—The experimental gas meter. the top of the stand, between the narrow stem of theburner and the surrounding glass tube, are to be placedpieces of commercial sesqui-carbonate of ammoniaweighing in all about 2 oz. The products, both of the combustion of the gasand of the gradual volatilisation of the ammonia, goupwards through the trumpet-tube into a vertical glasscylinder packed with glass balls (to break up the currentand promote condensation); from the top of this cylinder ANALYSIS OF COAL GAS. 249 a long glass pipe issues, and serves to effect somefurther condensation, as well as to regulate the draughtand afford an exit to the non-condensable gases. Inthe bottom of the cylinder is fixed a small glass tube,through which the condensed liquid arising from thecombustion of the hydrogen m the gas (and containmgt
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