44 JOURNAL OF THE 



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ash solution neutralized one c c. of the acid solution. Up to the 

 time of freezing these solutions were in every day use in the deter- 

 mination of nitrogen in our laboratory, had been very carefully pre- 

 pared in the beginning (by gravimetric determinations of SO3 in the 

 acid and careful titrations of the potash with the acid), and there 

 was no reason to believe that any change had taken place in the so- 

 lutions up to the time of freezing. 



In the cold snap alluded to both solutions froze solid and remained 

 so several days. Some time — perhaps a week — after the solutions 

 had thawed it became necessary to use them. That they had un- 

 dergone any change was not thought of, in fact that they had been 

 frozen was for the moment forgotten. When, however, I began to 

 titrate it was evident that the solutions were no longer in equilib- 

 rium. I then titrated successive portions of 10 c. c. of the acid so- 

 lution. I found that it required successively in c. c. of the potash 

 to neutralize, 11.03, 11.10, 11.10, 11.05, 11.05, 11.00, 11.02. These 

 titrations were made on Saturday, January 23d, and, as has been 

 stated, about a week after the solutions thawed. Appearances 

 pointed to the phenomenon that the solutions had in melting been 

 left in strata of different densities. Subsequent titrations seemed 

 to confirm this. On Monday morning (January 25th) I again titra- 

 ted three portions of 10 c. c. , each of the acid solution, both solu- 

 tions being so far undisturbed. It required 10.85, 10.80, and 10.80 

 c. c. of potash respectively. I then thoroughly shook up the pot- 

 ash solution, leaving the acid entirely undisturbed, and titrated 

 again in the same manner. Now it required of the potash solution 

 11.52, 11.50, 11.50 c. c. I then thoroughly shook up the acid solu- 

 tion and all subsequent titrations then gave 9.70; i. e., 9.70 c. c. pot- 

 ash solution to neutralize 10.00 c. c. of acid solution. Thus it was 

 seen that the freezing had apparently altered the strength of one or 

 both solutions. I then determined the strength of the acid solu- 

 tion, by precipitating the SO3 with BaCU in two separate portions 

 of 40 c. c. each. I got weights of BaSO^ 2.2527 and 2.2532 grammes; 

 mean, 2.25295 grs. BaSO^, equal to 0.0193412 gramme SO3 in one 

 c. c. instead of 0.02 grs. SO3 as it was made. Hence the acid solu- 

 tion had been apparently weakened by .00066 gramme SO 3 to the 

 c. c. or, almost exactly had lost /o of its strength. Hence it would 

 require only Ifi ot a c. c. of standard potash to neutralize one c. c. 

 of this altered acid, or 9.666 ^ c. c. to neutralize 10 00 c. c. The 

 facts show, by the titrations cited above, that 9.70 c. c. of the pot- 

 ash were required to neutraUze 10. c. c. of the acid, and it would 

 therefore appear that the potash solution was still standard — had 



