216. Judi: Aiec dll on the Tension of Vapor of Water. 
current observations. In general, such concurrences of the same 
mean temperature, give the mean of three observations of pres- 
sure; the result for 32° F., is the mean of forty-seven recorded 
pressures. For the experiments earlier than Mr. Southern’s, [ 
have usually taken only those whose recorded temperatures were 
already otherwise in the table. I shall have Reece however, 
to speak of each one more particularly, presently 
The difference of apparatus and manipulations necessary for 
experimenting upon the elasticity of vapor above and below the 
boiling temperature, has led several of the observers, for con- 
venience or other motives, to confine themselves to one or the 
other side of this limit; and would render proper, in any dis- 
cussion of the value and reliability of such observations, an ar- 
rangement of them in two distinct tables. But as I have no 
such aim at present, and as the aceon of the formula 
belongs equally to the. aah and highest temperatures, there is 
no reason for breaking the continuity of the comparison or for 
presenting the results in more than one table. 
The order of the different columns is chronological, according 
to the dates of execution; or, when that was not known 
lication of the experiments. As in fact each successive observer 
had, or might have had, thé benefit of the experience and pre- 
cautions of his predecessor, it may be presumed that this order 
represents too, in a measure, the respective reliabilities of the re- 
sults. Only the two French series, while they are evidently un- 
rivalled in the extent to which, in opposite directions, they have 
been carried, are similarly distinguished by the refined elaboration 
which characterizes every part of the research. 
Table of the Pressure of Sleam at different Temperatures, calculated 
and variously observed through a Range of 462 degrees of Fahren- 
- heit’s thermometer. 
eB heer, Pressure in M ury observed by 
eaot Ee 3 J 
22 Pa ee lg g ~ Dalton. | | 4s 
Pee €2.\ 3. Sale apes B. os ; a oe 5.5 - 
= c=) ; 
Be EE ed (e828 e8lez|23| 8 |B |EE| a2 | 2E | 28 
SW 5 A Oe eS ye ee oS EE re 
‘fe 6's —— 
27 TE ae  Lsthend < me |) ooh eg 
2. . (38 ; = 
Eg | Ses pi 
os tee OS ~~ 
ro , se a4. 
|e 2 2>8 
a5 - (886 23 
59 . . Hac Bas 
n* > |£o8 2s 
we 0-170 zs | ges 
500). | i he Se ale Ets 
a ; (0-200 0200 0-16 he 
. |. |*0-2290-29] . ; 
ki na ES es ; 01 
ss i . re", » * . ' 
a 
