308 morey: benzoic acid as standard 



of the oxalate to the carbonate, it was found that slight variations 

 in the rate or manner of heating might produce very discordant 

 results. The 0.1N factor calculated from the determinations 

 with sodium oxalate was 0.9982. 



Standardization of hydrochloric acid by benzoic acid. Because 

 of the bulkiness of the sublimed benzoic acid, it was found con- 

 venient to fuse or compress it before weighing. Fusion has the 

 advantage of diminishing the possibility of large surface effects. 

 A platinum dish was filled with the sublimed benzoic acid and 

 the covered dish placed in an oven heated to about 140°. When 

 melted, the liquid was poured into a test tube, and after solidi- 

 fying the stick so obtained was broken into pieces of convenient 

 size and preserved in a glass stoppered bottle. Samples so 

 prepared can be kept indefinitely and used without preliminary 

 drying. 



About a gram of this material was weighed and placed in a 

 300-cc. flask which had been swept free from carbon dioxide; 

 20 cc. of alcohol were added, the flask was stoppered and let 

 stand until the sample had dissolved. Three drops of a 1 per 

 cent solution of phenolphthalein were then added and the solu- 

 tion titrated directly with 0.1N alkali, a current of air free from 

 carbon dioxide bubbling through the solution until the titration 

 was completed. The end point chosen was that of a 7 per cent 

 transformation of the indicator added, that being the end point 

 which should give the best results. 5 The effect of the alcohol 

 on the end point was determined in a blank experiment and the 

 titrations corrected by this amount. This blank ranged from 

 0.06 to 0.08 cc. 



In the first series of experiments a solution of barium hydrox- 

 ide was used, this being the most convenient alkali to use when 

 exclusion of carbon dioxide is necessary. The mean of four 

 concordant determinations of the ratio HC1: Ba(OH) 2 was 

 1.3790. The mean of fifteen determinations, whose maximum 

 difference was 1 part in 1600, gave the value 0.9984 for the 

 0.1N factor of the HC1. In a second series of experiments the 



6 Noyes: Jour. Am. Chem. Soc, 32: 857. 1910. 



