Freezing-points of Solutions of Water in Formic Acid. 17 



In Table III. there are put down : c* calculated from the 

 equation above, and a taken from Table II., as also the 

 differences (c t * — c t = d\ff.). Putting t=S'52 in the equation, 

 we get for the anhydrous formic acid, c t = 5'65 . 10 -9 at 8°*52 C. 

 in terms of mercury at 0°. 



The temperature-coefficient can be determined according 

 to K . 10 4 from Table II. as 0*020, because the numbers for 

 K are nearly equal, which is shown in the diagram (fig. 2) by 

 straight lines passing through the same point. 



W. Saposchnikoff got for the most concentrated formic 

 acid the following results : — 



Freezing-points 

 of the acid. 



8-30 



8-344 



8-356 



8-39 



The last column is calculated according to the temperature- 

 coefficient 0'020. These numbers are not on the straight 

 line, but if we extrapolate a curve through the first three 

 observations, we get, from the diagram 2, for 8 - 39 F.-P. the 

 value 3'0, which agrees with that of Saposchnikoff (2'9) very 

 well indeed. 



Fig. 3. 

 c . 10 9 or c m . 10 9 (the dotted line). 







C at freezing 



c . 10 9 . 



t°. 



point. 



48 



16-5 



3-7 



4-7 



17-6 



3-5 



4-6 



18-5 



3-4 



4-0 



18-8 



2-9 































* 









































































































EE 





Co 



50 



40 











































S 













































6 













































4 

















































-30 



-., 









































z 





















































1» 











































20 









" '- 



-».. 







f 



























n 



















-«. - 



-°"° 



© - - 





































































-2 







/ 

















































,' 





i 





a. 





5 





^ 





S 





6 





7 





8% 



= f° 











X Z 3 4 5-ni, 



Phil. Mag. B. 5. Vol. 44. No. 266. July 1897. C 



