SATURATED 8TXAM, AND OTUEH VAPORS. 



Preuuro of 8team at Latitude 45. Bngiuh 8yiU. To radoee the 



the pressure of steam, ao that they will give the preaeure* io 



iida oo the aquare inch for degree* Fahrenheit, there are required the 



pariaon of meaaurea of length, and of weight, the comparison of the 



of the thermometer*, and the specific gravity of mercury. 



Profeaaor Rogers (/Yocwdfopt of Uu Am. Acad. of Art* and 

 188*-88> alao Additional Ofcenwrtoiw, etc. ) give* for the length of the metre, 

 2 incbea. Thla differ* from the value given Clarke (/v>- 



eaedtyt of tk* Royal Sod*y, vol. aw., 1866), by an amount that doea not 

 affect the value* in the tablea ; his value being 89.370432 incbea. 



i /'//. Transaction*, <<W) gives for the weight 



.am, 2.2 ; omuls. 



Regnault givea, for the weight of one litre of mercury, 13.5959 kilogram*. 

 1 lie degree Fahrenheit is | of the length of the degree Centigrade. 



; : 

 Ar= i 



thru the equations B and C have for the reduction to degree* Fahrenheit, 

 U on the square in 



log p = a, + log A- b*** + c/3*% 

 log p m a, 4- log * - Vi 1 " + 'i &*" 



The resulting equations, which were used in calculating Tablea I a. 



are: 



U. Fur steam from 32 to 212 F., in pounds on the square inch. 



log p O, - baf + Cft'. 



a, 8 3.025908. 

 tog 6 - 0.6117400. 

 logo 8.13204 - 10. 

 log a, - 9.998181015 - 10. 

 log ft = 0.0038134. 



* - I - : 



C. For steam from 212 to 428 F.. in pounds on the square inch. 



a, = 3*7 

 log 6j = 0.4121)* 

 logc, = 7.7-llrtH - 10. 

 log 4 - 9.998561831 - 10. 

 log ft = 0.0042! 



n t 

 All of the foregoing equations make the pressure a function of 



r the scale of the air-thermometer. It will be assume* 1 tint iiu- 

 i that scale and the absolute scale may be neglected. 



