COMPLEX SOLUTIONS. ARCHIBALD. 41 



temperature throughout the whole range of concentration 

 observed, the amount of the decrement diminishing with increase- 

 of concentration, until at a concentration of 0.7 it is only 0.6 

 per cent. 



Method of measuring Depression of the Freezing-point. 



Of the different methods described for the determination of. 

 the freezing point of salt solutions, that of Loomis* appeared to 

 me the best, and to give the most concordant results. His 

 method was accordingly followed in making the measurements 

 below. 



As it is most essential that the temperature of the room 

 where the observations are made should be near zero and as 

 constant as possible, the measurements were carried out during 

 the winter months in a basement room of Dalhousie College 

 building, where it was found possible to keep the temperature 

 below 2C and constant to within 0.5 of a degree for a couple of 

 hours at a time. No measurements were made while the tem- 

 perature of the room was above 2C. 



The thermometer was of the ordinary Beckman form, 

 graduated to 0.01 of a degree. No reading microscope being 

 available, I had to be satisfied with the use of an ordinary hand 

 lens for this purpose. Neveitheless, as the divisions of the 

 scale were about 0.6 mm. in length, I am quite satisfied that 

 I was able to read the temperatures to at least .001 degree. 

 The following readings of the thermometer made in an experi- 

 ment for determining the freezing point of water would seem to 

 imply that I succeeded in reading 'even more closely : 2.3415, 

 2.3410,2.3420,2.3415, 2.3420. Mean reading, 2.341C. Greatest 

 divergence from mean, .0006. 



The thermometer had never been calibrated, and as appara- 

 tus for this purpose was not available, I did not attempt to 

 calibrate it myself. The length of scale used for the following 

 measurements, however, was less than what corresponded to 

 1.4 degree, and for the more dilute solutions, say below 0.1 



* Phys. Review, 1, 199 and 274 (1893) and 3. 270 (1896). 



