Lerts & Buaxe—The Carbonic Anhydride of the Atmosphere. 151 
Disturbing effects produced in the titration of baryta water after 
it has remained in contact with glass.—On page 142 we describe 
two preliminary experiments which indicated that the titer of a 
baryta solution was affected by contact with glass in such a 
manner that its alkalinity was reduced. The experiments we have 
just described on the quantitative effects produced by such con- 
_ tact, might very naturally be supposed to confirm the result of 
those experiments, and we were therefore not a little surprised to 
find on repeating them, with every possible precaution, that instead 
of growing weaker owing to partial neutralization by silica dis- 
solved, or at all events removed from the glass, the baryta water 
actually experiences a slight increase in alkalinity which augments 
with the time of exposure. The experiments were made by 
allowing the weak baryta water to remain in receivers consisting 
of Winchester quart bottles with corks and attached tubes, as in 
fig. 1, p. 122, the air in them having been previously freed from 
carbonic anhydride, and the baryta water used for that purpose 
carefully washed out with water freed from carbonic anhydride. 
After a suitable interval the baryta water was drawn off into the 
vacuous titrating vessel, the receiver carefully washed out with puri- 
fied water, the washings being also drawn off into the titrating vessel. 
Immediately before or after the titration a blank determination 
was made of the alkalinity of the same quantity of baryta solution 
which had not been in contact with glass. 
Difference 
No. of Baryta Acid in acid 
Experi- Conditions. solution ee a d required 
ment. employed. quireG- | = increase in 
alkalinity. 
c.Cc. 
( Blanks : j ; é : 50 ¢.c. 49-95 
+ 0°40 
| In contact with glass 70 hours, é sy os 50°35 j 
( Blank, . é 5 : : is BS ihe 49-95 
2 + 0°40 
| In contact with glass 72 hours, : aie 50°35 
Blank, . , = : : 4 sus 49:95 
+ 0°65 
In contact with glass 118 hours, . nts 50°60 
Blank, . 6 ; S : 99) 09 49-29* 
4 + 2:01 
In contact with glass 15 days, . 2 cea. 51°30 
* Fresh acid solution. 
