Action of Hydrated and Nonhydrated Salts on Saponification. 91 



salt per cubic centimeter was subtracted from this weight, giving the 

 weight of the water per cubic centimeter of the salt solution. By 

 taking the reciprocal of this, the amount of the solution containing 

 an amount of water equal to 1 c.c. was obtained. The same trouble 

 was found with solutions of potassium iodide and sodium iodide being 

 colored, as Kellogg 1 describes. A drop of sodium thiosulphate was 

 used to decolorize the solution before titrating, as the color obscured 

 the change in the indicator. All solutions of the halogens were stand- 

 ardized as their silver salts. Calcium nitrate was converted into the 

 oxide, magnesium nitrate into the pyrophosphate, strontium nitrate 

 into the sulphate, and lithium nitrate into the sulphate by evaporating 

 with sulphuric acid. Magnesium sulphate was standardized as barium 

 sulphate, and the iodides of sodium and potassium were also determined 

 gravimetrically. 



THE ESTERS. 



The ester first employed was ethyl acetate. After some preliminary 

 work, this was discarded in favor of methyl acetate, since its solubility 

 in some of the strong salt solutions was so slight as to give us a hetero- 

 geneous system. Methyl formate was also studied, to see if the results 

 obtained with methyl acetate were of a general character or specific 

 to the ester in question. The esters, which were Kahlbaum prepara- 

 tions, were distilled several times until they boiled at the proper tem- 

 perature and their reaction was neutral. The methyl formate had to 

 be distilled frequently, on account of its apparent instability. 



THE BASE AND THE INDICATOR. 



The finding of the proper base and indicator to be used in titrating 

 the acid formed gave us quite a little trouble. Standard sulphuric 

 acid was made up, and on analysis found to contain 0.01205 gram of 

 sulphuric acid per cubic centimeter. This was used to standardize the 

 base, the comparison being repeated from time to time to see that the 

 base did not undergo any change in concentration. The acid was also 

 restandardized from time to time, no change in its concentration being 

 noticed. The alkali used first was alcoholic sodium hydroxide; the 

 indicator was phenolphthalein. The precipitate of sodium carbonate 

 was filtered from the alcoholic solution in an atmosphere free from 

 carbon dioxide, by a method similar to that employed by Morse. 2 The 

 alkali was one-tenth normal. Great difficulty was experienced in 

 obtaining good end-points with the above base and indicator. This 

 might be due to the saponification of the ester by the strong base, or to 

 the unfitness of the indicator. We therefore decided to test out dif- 

 ferent indicators and bases. 



KTourn. Amer. Chem. Soc., 31, 886 (1909). 'Exercises in Quant. Cheni.,330. 



