84

QUANTITATI VK ACRK',1 'l/l't^:liAL .1 .V.I A r.s'AV

tubes. One of these is for entering air. K. iHaUnrhed to ;i lube of .soda lin
outside and it extends to the bottom of tin* bottle. (Tin- suda lime must b<>
well confined by a filter of cotton.) The either tube is eonneetrd with an
air pump. The purified air is then drawn through th«* w.'iter for an hour,
after which the bottle is stoppered.
The three reagents may be placed on n shelf «nd eonneeted us shown in
Fig. 22, for convenient use.

/"     A
Standard BafOHfe | | Standard HC1 0 | | Water/Oj-Frw /"„
< | UN)                                                        < | ;^M        "   f

pig. 22.— Assembly of reason tn for flu*

*lioxt«li» f)i*ti*rrninfitirm.

Determination of the Carbonate Radical: VolurnHrir Mrtktxl. ..... - A«m?mble
the apparatus discussed above, the Meyer absorption tut«* brniig half filled
with distilled water. Close the cock of funwl /I find ti*«t fur li'iikn by
opening cocks k, f and e. Water will flow from thi* nHpirntor until tho
pressure within the apparatus ih reduced to equilibrium with the water
column. If an air leak exists at any point between B am) the Meyer tubft
air will bubble slowly through the tube. Any leak thus evidenced mu«t be
located and stopped.
The clamp at k is now closed and the. eock of the dropping funnel H in
opened. With c and / left open k m no itdjusti'd iih t<i allow ftlmut thn»o
bubbles of air per second to pass through tin? Meyer tube*. Clump A- m not
thereafter changed and this keeps the gas flow wider mntrol .Now rkwe/
and remove the flask A. Weigh into this about 0.3 grn erf the* sample* of
carbonate. One-half of the factor weight (pawn 3 iircl K> itmy In* uned, if
desired. This would be 0.2750 %m for a ftwrth-norniftl wilntioti, or 0.21500
gin for the solution of which 1 cc is equivalent to 0.005 grn of carbon dioxide.
(The student should prove this statement,)