VOLUMETRIC METHOD FOR ESTIMATING SULPHUKIC ACID. 217 



not containing sulphates this proportion of spirit can be 

 added at first, and the titration carried out in the ordinary 

 manner, when it will be found that a decinormal solution 

 of sodic carbonate is equivalent to a similar one of either 

 calcium or barium chloride, a correction being made for the 

 acidity, found by the carbonate solution, of the total spirit 

 used in the titration. It is, however, advisable to stan- 

 dardise the sodic carbonate against a standard barium 

 chloride solution under the same conditions. I have not 

 yet tried the reaction with strontium, but there is no 

 reason why the method should not be similarly applicable 

 to it. 



Estimation of calcium. — 10 cc. of a solution of calcium 



chloride containing *1532°/° calcium required 7*65 cc, 7*6 cc, 



N 

 7*7 cc. of — sodic carbonate — mean 7*65 cc 



7*65 cc. are equivalent to '01522 g. of calcium. 



Estimation of barium. — 10 cc. of a solution containing 



*6868°/° of barium required 10*05 cc, 10*10 cc, 10*05 cc, 



N 

 and 10*10 cc. — mean 10*07 cc. — — — sodic carbonate 



10*07 cc. are equivalent to "06867 g. of barium. 



In estimating calcium in presence of sulphuric acid one 

 of the following methods may be adopted : either the spirit 

 may be added gradually, so as not to precipitate the lime 

 as sulphate : or having by a preliminary test carried out by 

 means of a gradual addition of spirit found the approximate 

 amount of sodic carbonate required, a slight excess can be 

 run in, then the proper proportion of spirit added, and the 

 true amount of sodic carbonate required found by titrating 

 back with a dilute standard solution of hydrochloric acid 



1 cc. of— HC1 being equivalent to 1 cc — Na 2 00 3 



Estimation of Sulphuric Acid in a solution containing fixed 

 alkalies only.— Any acidity of the solution is neutralised 



