144 ON THE DEPRESSION OF THE FREEZING-POINT 



determination of the reduction factors were available only at 

 18, but as the cell was of glass its value at would not be 

 practically different from that at 18. 



The water bath used in the observations of the conductivity 

 at 18 was the same as that described in my former paper. In 

 the case of the observations at the bath was modified so that 

 the temperature could be kept constant at by means of pieces 

 of ice floating in it, while the water was kept continually stirred. 

 The ice was prevented from coming in contact with the cell by 

 placing around the cell a cylindrical screen of wire gauze 17 cm. 

 in diameter, and reaching to within 10 cm. of the bottom 

 of the bath. By the addition or the removal of pieces of 

 ice from the salt water, the temperature of the bath could 

 easily be kept within one twenty-fifth of a degree for a sufficient 

 time to make the measurement of conductivity. The observa- 

 tions were made in a basement room of the college, where the 

 temperature, during the winter months, was generally below 6C- 

 The thermometer used was graduated to a fiftieth of a centi- 

 grade degree and its zero point was determined by the writer. 

 Each solution was brought to about before it was placed in 

 the cell, and while in the cell successive observations of the 

 conductivit} 7 were made to insure that the temperature of the 

 bath had been taken. 



The method employed for finding the freezing-point of the 

 solutions was the same in principle as that proposed by 1 Loomis 

 The size of the protection bath was larger than that used by 

 Loomis, and the stirring was done mechanically. 



The thermometer used was of the Beckmann form. It was 

 graduated to a hundredth of a degree, and could be read to a 

 thousandth by aid of a small microscope, mounted on an upright 

 stand. This thermometer was at a certain place on its stem 

 firmly fixed in the cork of the inner freezing-tube (the freezing- 

 tubes consisted of an inner and outer tube, the inner containing 

 the solution whose freezing-point was measured) so that when 

 in position its bulb was within 2 cm. of the bottom of the tube. 



1 Phys. Review, 1, 199, 1893 and 9, 257, 1897. 



