0^2 DILATATION OF THE GASES. 



Of atmofpherlc uncertainty that I could fufpecr, I obtained the following fix 

 aif ' refults from fix experiments on atmofpheric air *. 



f 137,40 

 From the temperature of melting ice 137,61 



to that of boiling water, equal vo- J 137,44 

 lumes of atmofpheric air reprefented ^ 137,55 

 by 100, became - I l. r >7,48 



L 137,57 

 f The mean refult is about - 137,50 



for each degree, Jf the total augmentation of volume be divided by the num- 

 ber of degrees which produced it, or by 80, it will be found^ 

 by making the volume at the temperature equal to unity, 

 that the augmentation of volume for each degree is ^fy.??* or 

 Yrg.ss f° r eacn degree of the centigrade thermometer. 

 This refult does As Deluc obtained. T | T for his coefficient, it feems at firft 

 Dduc. ree Wt fiftkt that our refults are the fame ; but if it be obferved that he 

 began at the temperature 16°%, and that I began at 0°-| it 

 will be feen that our refults are coniiderably different. I fhall 

 explain this difference elfewhere, and (hew that the coeffi- 

 cients of dilatation vary according to the temperature of com- 

 mencement. 

 Ixpanfionofhi- Hidrogen gas obtained from iron by weak fulphuric acid 

 drogcnt was fubmitted to two experiments : in one, by an elevation of 



temperature from the degree of melting ice to that of boiling 

 water, 100 parts became 137,49; and in another by the 

 fame elevation of temperature 100 parts became 137,66. The 

 mean of thefe two refults is 137,52, which differs very little 

 from the mean refult of the dilatation of atmofpheric air. 



* My receiver contained about 350 grammes of water (a little 

 more than 12 ounces) 



f Though the difference between thefe refults are not very con- 

 ficlerable, I think I might have rendered them lefs fo, if I could 

 have kept an account, of the ftate of the barometer at the moment of 

 the ebullition of the water. I have, however, always had the pre- 

 caution to be affined of its thermometrical ftate at the moment of 

 ebullition, in which I can affert that I never found any very fenfi- 

 ble variations. A variation of an inch of the barometer would in 

 fact be neceffary to occafion one, of a degree, in the place of the 

 billing point j which can felc'om happen. However this may be, 

 thii mean refult 137,50 nauft be very near the truth. 



Oxigen 



