PHILOSOPHICAL TRANSACTIONS. 



231 



VOL. LXVII.] 



permit the surface of the column to be distinctly seen and read off, it had risen 

 to +14°; the temperature of the air, and also of the standard barometer, being 

 at the same moment 4 Qi". The observed condensation, arising from this dif- 

 ference of 35-i-°, was -rVo-ths of an inch ; or .1 J 89 when reduced for the height 

 of the barometer, which then stood at 30. 296. Hence the condensation for 

 32° is .1072, or .00335 for each degree. In this day's experiment, when the 

 temperature of the mixture had risen to 32°, that of the air and standard baro- 

 meter was 524-° ; whence the reduced difference, for the 20° between 32° and 52° 

 was found to be .0664 answerable to former experiments. 



The same experiment was repeated 2 days after, with great care, the vessel 

 being filled no higher than the surface of the quicksilver. The mean tempera- 

 ture of the mixture was now -|- 4°, and that of the standard barometer 491°. 

 The observed condensation, arising from this difference of 45-i-°, was ,'„Vo ? or 

 .1594 when reduced for the height of the barometer, then standing at 30.416 : 

 hence the rate for 32° is .1127, or .003522 for each degree. When the tem- 

 perature of the mixture had risen to 32°, that of the air was 51°: whence the 

 augmented rate for the 20°, between 32° and 52°, was found to be .0662. 



From the mean of these 2 experiments it appears, that the condensation of a 

 column of 30 inches of quicksilver in the barometer, affected by the 32° of 

 cold below freezing, is .IO99: and that the expansion from 20° of heat, be- 

 tween 32° and 52°, ._ , „ 



Rate of expansion of a column 0/ quicksilver in the tube of 



a barometer. 



is .0663, a 

 number agreeing perfectly well 

 with former results. If the con- 

 densation .1099, thus found, be 

 added to the expansion .5117 

 arising from the 2d class of ex- 

 periments, we shall have .6216 

 for the total difference of height 

 of the columns of quicksilver in 

 2 barometers, sustaining the same 

 pressure, but differing from each 

 other in their temperatures 212° 

 of Fahrenheit's thermometer. 



The series of numbers expres- 

 sed in the annexed table, agree- 

 ing in all essential respects with 

 the expansions found by experi- 

 ment, will therefore show that 

 which corresponds to any inter- 

 mediate temperature, for every 

 10° of the scale. 



§•5 



> O o 



O J3 • = 

 TO (« cr 



.9 X 





u * K O-B 



>-.0007 



Differ. 2(1 Difltr. 



.0229 

 .0236" 

 .0243 



.0250 , 



.0257 I 



.OJ64 J 



.0271 i 



.0277 



.0283 



.0289 



.0-95 



.0301 



.03(-7 



0006 



r 



.0313 J 

 .0318 1 

 .0323 

 .0328 I 

 .0333 

 .0338 

 .0;i43 

 .0348 

 .0070 J 



>.0005 



