SPECIFIC GRAVITY AND DISPLACEMENT OF SOME SALINE SOLUTIONS. 193 



Table III. 



Giving Details of the Order of Succession of the Experiments, of their Duration, 

 and of the Temperatures of the Solutions and the Air respectively during 

 the Experiments made on the Solution, 7 '225 CaCl^^- 1000 grams of Water. 



Number of 

 Experiment. 



(1) 



Time of Com- 

 mencement of 

 Experiment. 



(2) 



Time of Com- 

 pletion of 

 Experiment. 



(3) 



Duration of 

 Experiment. 



(4) 



Time Interval 



between 



Successive 



Experiments. 



(5) 



Initial and 

 Final Solution 

 Temperatures. 



(6) 



Initial and 



Final Air 



Temperatures. 



(7) 



Hydrometer. 

 (8) 



1 



10.45 a.m. 



11.5 a.m. 



20 minutes 



25 minutes 



19-5° C. 

 19-5° C. 



19-3° C. 



19-rc. 



A 



2 



11.30 a.m. 



11.45 a.m. 



15 minutes 



25 minutes 



19-5° C. 

 19-5° C. 



19-3° C. 

 19-3° C. 



B 



3 



12.10 p.m. 



12.25 p.m. 



15 minutes 



10 minutes 



19-5° C. 

 19-5° C. 



19-3° C. 

 19-4° C. 



A 



4 



12.35 p.m. 



12.49 p.m. 



14 minutes 



6 minutes 



19'5°C. 

 19-5° C. 



19-4° C. 



19-3° C. 



B 



5 



12.55 p.m. 



1.5 p.m. 



10 minutes 





19-5° C. 

 19-5° C. 



19-3° C. 

 19-35° C. 



A 



§ 111. Comparison of Results obtained with Hydrometers A and B when floating 

 in the Supersaturated Solution of Calcium Chloride with those obtained when the Hydro- 

 meters are floating in a Solution containing 6 "3 gram-molecules of Calcium Chloride in 

 1000 grams of Water. — We will first draw attention to Table III., which gives the dura- 

 tion of each experiment, the initial and final solution temperatures, and the air tempera- 

 tures before and after each experiment, in connection with the observations and results 

 recorded in Table IIa. Table III. also affords a fair criterion of the usual duration 

 of these experiments, and it gives suitable relief to the constancy of the temperature, 

 both of the experimental liquid and of the atmosphere of the laboratory, which can, 

 and must be secured, if the full precision of which the hydrometric method is 

 susceptible is to be achieved. It will be observed that the temperature of the air 

 was generally 0-2" C. lower than that of the experimental liquid, and that, in these 

 conditions, the temperature of the experimental liquid remained perfectly constant 

 during the time of the experiment. The absolute degree of constancy covered by this 

 statement depends on the specification of the thermometer used. It was a standard 

 instrument, divided, on the stem, into tenths of a Centigrade degree, and the length 



TRANS. fiOY. SOC. EDIN., VOL. XLIX., PART I. (NO. 1). 25 



