60 



Scientific Proceedings, Royal Dublin Society. 



which is given in the second-last column. The greatest divergence is not 

 5 per cent. In the final column are given the actual freezing-points of the 

 solutions derived from Eaoult's results quoted from Hamburger {/oc. cit.). 



Depression of Freezing-point in hundredths of degree centigrade. 

 SO 100 ISO 200 



250 



C5 



so 100 ISO 200 



Deflection in millimetres. 

 Fig. 4. 



It will he noticed from the positions recorded in the table that the position 

 of the zero shifted considerably duriug the observations. In the first series, 

 i.e., those on solution I., the zero point lay about 251 on the scale, while during 

 the first observation on solution II. it was near 254. These shifts of zero 

 show the importance of being able to reverse the current, and of obtaining the 

 deflection by two readings, one on each side of the zero position. 



A graph of these observations is given in fig. 4. The ordinates correspond 

 to. the concentration of the solutions, and the abscissse are the measures of the 

 deflections in mm., caused by the difference in temperature of the freezing- 



250. 



