222 
IOWA ACADEMY OF SCIENCE 
from pure water in platinum. A second preparation was made 
with specially prepared potassium carbonate, made by repeated 
precipitation of the acid carbonate from the normal carbonate 
with carbon dioxide. After drying in the air each sample was 
heated in a platinum dish in an air bath for several hours 
at 125°. 
The following are the titrations made with the first prepara- 
tion. The first three were made with the solution of sodium hy- 
droxide having the ratio to the hydrochloric acid 1 to 1.10991 ; 
all the remaining ones in this paper with the alkali having the 
ratio 1 to 1.1859. 
Calculated HCl in 
Weighed acid 1 gram of solution 
Weight of NaOH. potassium phthalate. of HCl. 
1. 64.275 1.4583 .0036517 ‘ 
2. 68.479 1.5531 .0036503 
3. 96.585 2.1933 .0036548 
4. 59.670 1.4483 .0036565 
5. 49.471 1.2000 .0'036542 
Average of five determinations 0036535 
The data of the second series give practically the same value. 
Calculated HCl in 
Weighed acid 1 gram of solution 
Weight of NaOH. potassium phthalate. of HCl. 
1. 71.7335 1.7380 .0036500 
2. 56.660 1.3733 .0036513 
3. 71.243 1.7287 .0036554 
4. 78.108 1.8943 .0036535 
5. 52.367 1.2692 .0036512 
. Average 0036523 
The amount of HCl in 1 ce. of the solution, calculated under 
silver chloride is .0036484. 
Acid Sodium Phthalate. This salt has about the same solubil- 
ity in hot and cold water as the acid potassium salt. It crystal- 
lizes with approximately one-half molecule of water. Its equiva- 
lent is also high, 188.04. 
Three preparations of this salt were made by the same method 
and with the same care as described under the potassium salt. 
It was crystallized six times from hot water, and dried in the 
atmosphere of the laboratory. Many titrations were made to de- 
termine whether the hydrous salt would show sufficient con- 
stancy to serve as a standard. Three determinations of the 
water of crystallization were made using large quantities of the 
salt each time. All these determinations showed considerable 
variation depending apparently on the state of the atmosphere 
