260 PHILOSOPHICAL TRANSACTIONS, [aNNO 17Q2. 



that a quantity equal to 1.5 had adhered to the upper part of the tubes, and no 

 well-grounded objection can be made to this, when we consider that 1 division is 

 only equal to .015 of a grain of spirit, in this instrument. 



It appears then from the preceding experiments, that the mean of the quan- 

 tities found, on heating up from 30° to 100°, including the error that must arise 

 from some of the fluid adhering to the tube, in cooling it down from 6o° to 30°, 

 previous to its being heated up from 30° to 100°, gives for the total expansion of 

 the spirit 396.75; and in cooling down from 100° to 30°, 3gS.O; the difference 

 is 1.25; but I have already shown that this difference is not so great as it would 

 have been had it not been cooled down from 60° to 30°: if therefore we say, as 

 232 : 1,25 : : 164 : 0.88, it is evident that the latter quantity must be subtracted 

 from 396.75, and there will remain for the total expansion of the spirit by this 

 instrument, in heating up from 30° to 100°, 395.87, which is different from the 

 experiments by weight 1 .68 division, in defect. 



The following are experiments made with the same instrument, and a mixture 

 of equal parts of spirit and water, being some of the same which was used in 

 the former experiments. Having charged the instrument with this mixture, it 

 was immediately put into a vessel of water, whose temperature was 6o°, and the 

 mixture was found to stand in the 2 tubes at 3.5 above O, I then cooled it down 

 to 30°, and it sunk to 122 below 0. I heated it up to 100°, when it was found 

 to rise to 188 above 0. It was afterwards brought to the temperature of 60°, 

 and suffered to remain in that temperature for 3 hours, when it was found to 

 stand at 6 above O. 



It appears from the above experiments, that the contraction in cooling down 

 from 60° to 30°, is 122 + 3.5 = 125.5; and on heating it up to 100°, we have 

 for the total expansion from 30° to 100°, 122 + 188 = 310; but it is obvious 

 that this total expansion cannot be the true one; for it appears, on suffering the 

 instrument to remain 3 hours in the temperature of 6o°, that it was found to 

 have collected a cjuantity = 2.5, that had undoubtedly adhered to the upper part 

 of the tube when charged, and the fluid having arrived at the temperature of 60° 

 sooner than what adhered could descend, it was of course left behind on cooling 

 the mixture down to 30°; if therefore that quantity had been collected while it 

 remained at the temperature of 6o°, it would have stood at 6 above O, and the 

 contraction from 6o° to 30° would have been 1 ig.5 + 6 = 125.5 below 0; and 

 the total expansion from 30° to 100°, = lig.S -|- ]88 = 307.5 instead of 310, 

 as found before; and differing from the experiments by weight 3.07 divisions, 

 in defect. 



The same mixture having been suffered to remain in the instrument, which 

 was hung up as before, the following experiments were tried 2 days afterwards. 

 Having brought the n)ixturc to the temperature of 60°, it was found to stand in 



