276 PHILOSOPHICAL TRANSACTIONS. [aNNO 1792. 



expansion in heating up from 6o° to 100° was 185 — 1.5 = 183.5, but the con- 

 traction in cooling down from 100° to do° was 185 — 2.5 = 182.5. In heating 

 up again to 100° it was 185 — 3 = 182, but in cooling down again to 6o°, 185 

 — 2.5 = 182.5; the mean of the 4 is 182.62, and the total expansion from 30° 

 to 100° = 308,87; differing from the experiments by weight 1.7 division, in de- 

 fect. The difference between the 2 methods of heating up from 6o° to 100°, 

 and cooling down again from 100° to 6o°, taking a mean of the 2 heatings, and 

 the mean of the 2 coolings, is 0.75 of a division. 



The contraction by the small instrument, in cooling down from 6o° to 30°, 

 was 124.5 -j- 1 = 125.5. On heating up again to 6o°, the expansion was the 

 .same. In heating up from 6o° to 100° the expansion was 183.5 — 1 = 182.5; 

 but in cooling down to 6o° again, the contraction was 183.5 -f- 1.5 = 185. In 

 heating again up to 100°, the expansion was 180.5 -{- 2 =. 182.5; but in cool- 

 ing again to 6o° the contraction was 180.5 -|- 4 = 184.5. The mean of these 

 4 gives 183.62, for the expansion from 6o° to 100°; and therefore the total ex- 

 pansion from 30° to 100° will be 309.12, differing from the expansion found by 

 the experiments by weight 1.45 division, in defect. The difference between the 

 mean of the 2 heatings up from 6o° to 100°, and the 2 coolings down from 100° 

 to 6o° again, is 2.75 divisions. 



The mixture made use of in the above experiment was now emptied out, and 

 the instruments were charged with more of the same, preparatory to the fol- 

 lowing experiments. The mixture being brought to the temperature of 6o°, 

 was found to stand in each of the instruments at 1.5 above O. It was then 

 cooled down to 30°, and it stood in the long instrument 124.5, and in the short 

 one 125 below 0. It was then brought back to the temperature of 6o°, and it 

 stood in the long instrument 1.5 above O as before, but in the short one 1 above 

 O only. I heated the mixture to 100°, when it stood at 182.5 in the long in- 

 strument, and in the short one at 183.5 above 0. The mixture was afterwards 

 brought to the temperature of 6o°, when it was found to stand at in both in- 

 struments. 



It appears from the preceding experiments, that the contraction of this mix- 

 ture in cooling down from 6o° to 30°, by the long instrument is 124.5 + 1.5 

 =r 126, and the expansion in heating up again from 30° to 6o°, the same. The 

 expansion in heating up from 6o° to 100° was 182.5 — 1.5 = 181 ; but in cool- 

 ing down again from 100° to 60", the contraction was 182.5; the mean is 181.75, 

 and the total expansion from 30° to 100° will be 307.75, differing from the ex- 

 periments by weight 2.82 divisions, in defect. The difference between the 2 

 methods of heating up from 6o° to 100°, and cooling down again from 100° to 

 6o°j is 1.5 division. 



The contraction of the mixture in cooling down from 6o° to 30°, by the short 



