A manual of practical hygiene for students, physicians, and health officers . providedin place of corks or rubber stopiiers, though ifthese are not at hand, the latter may be used ; butnote should be made of the volume of air whichthey displace when they are inserted. Solutions Required.— 1. Solution OF Bat{iu:mIIvDRATK.—Dissolve about grams of liariumhydrate and of barium chloride in a liter ofdistilled water which ju-eviously has been boiled,in order to ex]iel any carbon dioxide which it maycontain. It is well to prepare an amount suf-ficient for future needs, say 4 liters, and to ke
A manual of practical hygiene for students, physicians, and health officers . providedin place of corks or rubber stopiiers, though ifthese are not at hand, the latter may be used ; butnote should be made of the volume of air whichthey displace when they are inserted. Solutions Required.— 1. Solution OF Bat{iu:mIIvDRATK.—Dissolve about grams of liariumhydrate and of barium chloride in a liter ofdistilled water which ju-eviously has been boiled,in order to ex]iel any carbon dioxide which it maycontain. It is well to prepare an amount suf-ficient for future needs, say 4 liters, and to keepit in a bottle such as is shown in Fig. 14. Thisis provided with a rubber stopper with two per-forations, through one of which a bent tube, reach-ing to the bottom, and intended for withdrawalof the reagent, is inserted. Through the umice soaked while hot in a strongsolution of caustic potash. The delivery tube carries at it* outer. Bottle for V>ariumhydrate. 304 AIR. end a piece of closely fitting rubber tubing, which is kept closed bymeans of a pinehcock. In withdrawing the reagent for use, a 100 cc. pipette is insertedinto the free end of the rubber tube, suction is applied, and thepinehcock is opened. AVhen the pipette is filled to the mark, thepressure is removed trom the })inclicock and the ])ipette released. Asthe reagent is withdrawn, air fiows in through the other opening, andis robbed of its carbon dioxide by contact with the caustic potash withwhich the pumice has been charged. This reagent is used for theabsorption of the carbon dioxide contained in the sample of air underexamination. The reaction is expressed by the following formula: BaO^H,+CO,=BaC03+H20. The function of the barium chloride is explained below. 2. Standard Solution of Oxalic Acid.—Dissolve gramsof pure oxalic acid in a liter of distilled water. One cc. of this solu-tion is equivalent to cc. of carbon dioxide; that is t
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Keywords: ., bookcentury1900, bookdecade1910, bookpublishe, booksubjecthygiene
