56 MR J. Y. BUCHANAN ON THE 



seated at the table making observations. The door of the fume chest being closed, the 

 heat from the bunsen is very evenly distributed into the room. 



The two hydrometers which were used in the experiments were taken from their 

 cases, were each immersed in a small cylinder containing distilled water at about 1 9 '6'' C, 

 and left in to attain a temperature about 19 50° C, a temperature at which the specific 

 gravity observations were to be made. 



The solution used on this occasion was a ^ gram-molecule solution of the potassium 

 chloride and iodide mixed in equimolecular proportions, the molecular weight assigned 

 being the mean between the molecular weight of potassium chloride and that of 

 potassium iodide. The weight of salt represented by y^ gram-molecule was dissolved 

 in 1000 grams of water and was prepared overnight. 



The bottle of solution had been standing near the radiator for some time to attain 

 a temperature near to 19 50° C. 



The solution was now poured into the cylinder used for the experiments, and the 

 quantity was such that when the largest hydrometer was immersed to its fullest extent 

 the surface of the solution was fully an inch below the rim of the cylinder, a precaution 

 which obviates difficulties in reading likely to be occasioned by irregularities in the 

 glass occurring near the top. 



The cylinder containing the solution was then placed on the table at a convenient 

 altitude for making observations (the foot of the cylinder resting on a thickness 

 of sixteen folds of soft German filter paper to form a non-conducting surface), and 

 the temperature, as observed with a standard thermometer divided into yV^li^ inch, 

 each division being of such a size as to enable one to read y^^jths of a degree in 

 temperature with comparative ease, was 1870° C, the air temperature by this time- 

 being 19-0° C. 



An expeditious and effective method for rapidly raising the temperature of the 

 cylinder and contents, by stroking the side of the cylinder with the palms of the hands, 

 was adopted, and by this means the temperature was quickly raised to 19'50°C. exactly. 



The time was then 10.50 a.m., and the room temperature 19' 1 C, so the bunsen 

 was lowered somewhat, and the radiator turned to half way. 



On removing the hydrometers from their respective cylinders and drying them, the 

 temperature of the water in which they had been immersed was 19"35° C. in both cases, 

 so that the hydrometers were presumably at that temperature. 



The temperature of the solution was still at 19*50° C, and the air temperature 

 19*20° C, so that the conditions were suitable for commencing observations. 



After removing the thermometer from the solution and immersing it in one 

 of the cylinders of distilled water, the hydrometer No. 17 was taken from its case 

 and gently lowered into the solution, and an initial added weight placed on the 

 top of the stem of the hydrometer, the time of commencement of the experiment 

 being noted. 



Nine successive readings, as the results of addition of nine weights, eight of them 



