ACID POTASSIUM AND ACID' SODIUM PHTHALATES 219 
Grams of Solution. 
Weight of AgCl. 
HCl to 1 Gram 
of Solution. 
1. 
(Air weight.) 
64.215 
.9221 
.0036535 
2. 
57.318 
.8232 
.0036541 
3. 
63.945 
.9185 
.0036546 
4. 
107.876 
1.5489 
.0036532 
5. 
99.748 
1.4323 
.0036534 
Average of five 
determinations 
0036536 
This value is for 1 gram of the HCl solution weighed in air. 
However, if the weight of the acid be reduced to vacuum stan- 
dard the value becomes ,0036497. The density of the solution 
was determined with a Sprengel picnometer at 20° as compared 
with water at the same temperature and was found to be 1.0018, 
and since the density of 1 cc. of water at this temperature is 
.9982, the density of the solution at 20°=.9982Xl-0018=l-d00d- 
Therefore one has also the value of 1 cc.=.0036497, of HCl. 
Alkali Solution. Solutions of both barium and sodium hy- 
droxides Were prepared but the former seemed to have no ad- 
vantage over the latter and had the disadvantage that the pre- 
cipitates formed in titration interfered somewhat with judging 
the end points. It was soon discarded in favor of the sodium 
hydroxide. 
Somewhat more than the required weight of sodium hydrox- 
ide, purified by alcohol, was weighed, sprayed with a little 
water to remove superficial carbonate and dissolved in about a 
liter of water. A slight excess of barium hydroxide solution 
was added to precipitate the carbonate and the excess of barium 
was precipitated with sodium sulfate. It was filtered rapidly, 
without waiting for all of it to pass through, into a large bottle 
which had been filled with air free from carbon dioxide. It was 
then made up to about four liters with the twice distilled water. 
The bottle was fitted with a glass stoppered buret which was 
filled through its side tube also provided with a glass stopper. 
Both buret and bottle were provided with long calcium chloride 
tubes filled with bits of solid potassium hydroxide. The tube 
connected with the bottle was in turn connected with a bottle 
containing a solution of concentrated caustic potash over which 
the air remained till drawn into the bottle containing the stand- 
ard alkali, in filling the buret. Over the tip of the buret was 
kept a rubber cap. The weight buret was filled from the volume 
buret, the tip of the latter being inserted far into the neck of 
the weight buret. ' A small amount of carbonate in the alkali 
