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TRANS. ST. LOUIS ACAD. SCIENCE. 



capacities varying from 30 to 210 ccm. The temperatures were 

 measured by the thermometers used in the determinations of spe- 

 cific heats ; they were read to 0.01° C, and it will be apparent, 

 that, in those cases where the changes of temperature were only 

 slight, the error could amount to a considerable percentage of the 

 total. The results obtained will be found in Tables I. and II., 

 given below. 



The determinations were made at 18° C. 



In Table I. n signifies the consecutive additions of the difterent 

 equivalents of water to one equivalent of acid. The number of 

 calories thereby evolved is given in each case under each of the 

 four acids heading their respective columns. I append also the 

 results obtained by Favre for acetic acid. It will be seen that the 

 coincidence is quite close. 



For convenience sake I have laid out the values obtained in 

 curves. In Fig. III. the ordinates represent the number of calor- 

 ies, positive or negative, above or below the zero line, while the 

 nurnber of equivalents of water added n' are the abscissas. 

 Table I. 



For valerianic acid I found the negative thermal effect re- 

 sultant on its union with \ equivalent of water to be — 339 g. 

 calories. 



