CHEMISTRY — MORSE. 



199 



Two series of measurements, one at 10° and the other at 15°, were made 

 with cane-sugar sohitions, the concentrations being the same as in the case 

 of glucose. A table is appended in which are given a summary of the results 

 at 10° and 15°, and also, for purposes of comparison, those which had previ- 

 ously been obtained at 0° and in the vicinity of 5°. 



Concentration. 



O.I 



0. 2 



0.3 



0.4 



C.5 



0.6 



0.7 



0.8 



0.9 



I.O 



a) Total pressures 



b) Mean molecular osmotic press- 



ures 



c) Mean molecular gas pressures. . . 



d) Mean ratio of osmotic to gas 



pressure 



Series III 



pressures 



(0°). 



2.42 



4.79 



7. II 



9-35 



11.75 



14.12 



16.68 



19-15 

 21.89 



24.45 



131-71 



23-95 

 22.29 



1.074 



Series IV 

 pressures 

 (4° to 5°). 



2.40 



4-75 

 7.07 



9-43 

 11.82 



14-43 

 16.79 



19-31 

 22.15 



24-53 



Series V 



pressures 



(10°). 



132.68 



24.12 

 22.65 



1.065 



2.44 

 4 82 

 7.19 

 9-58 

 12.00 



14-54 

 17.09 



19-75 

 22.28 

 25.06 



134-75 



24.50 

 23.09 



1. 061 



Series VI 



pressures 



(15°)- 



2.48 

 4.91 



7.33 



9.78 



12.29 



14.86 



17-39 

 20.09 

 22.94 

 25.42 



137-49 



24.98 

 23-50 



1.064 



To facilitate a comparison of the results presented in the table, there are 

 given: (i) the total number of atmospheres of pressure which were meas- 

 ured in each series (horizontal line a) ; (2) the mean molectilar osmotic 

 pressure in atmospheres (horizontal line b) ; (3) the corresponding molecular 

 gas pressures (horizontal line c) ; (4) the ratio of the osmotic pressures 

 found to the calculated gas pressures at the same temperatures (horizontal 

 line d). No extended discussion of the data presented can be entered upon 

 in this report, but it will be noted that there is a continuous increase in 

 pressure with rising temperature (lines a and b), indicating the existence of a 

 temperature coefficient ; also that the osmotic pressure is steadily in excess of 

 gas pressure (lines b and c.) The most important conclusion to be deduced 

 from the results is arrived at when osmotic is compared with gas pressure 

 at the different temperatures (line d). Except in the case of the series at 

 0°, the ratio of the two is practically constant, showing that, between 5° 

 and 15°, the osmotic pressure of cane-sugar solutions obeys the lazv of Gay- 

 Lussac for gases. A more recent series of measurements, not quite com- 

 pleted, shows that the same relation holds up to 25°. The ratio of osmotic 

 to gas pressure at 0° is somewhat higher than at 5°, 10°, and 15°, namely, 

 1.074 as against 1.065, I-061, and 1.064 (^ii^e d) ; but the series of determina- 

 tions at 0° was made before the method of measuring osmotic pressure had 



