Southern on the Latent Heat of Steam. \ \ 7 



if W = weight of cold water, T = its temperature 

 10 = accession of water by the condensed steam, 

 t = the temperature of warm water, and 

 .r = the sum of the latent and sensible heat of the 

 steam condensed, 



W + w.^-WT 



+ X. 



w 



Either of these equations will be found to give in the three 

 experiments 1157°, 1244°, and 1256°, from which subtract 

 the numbers, col. xi. 229^, 270^, and 295=, and there re- 



'"'"" • \' ■ 928°, 974°, and 961°, the latent heat. 



1 hree other experiments were instituted with the intention 

 ot ascertaining the latent heat of steam under the three same 

 degrees of elasticity, viz, equal to the support of 40, 80 and 

 120 inches of mercury. The steam was raised or generated 

 ni the same boiler used in the previous experiments, and from 

 the end of a cast-iron pipe of U inch diameter which united 

 with It, a small copper pipe was taken (its diameter about 

 % inch) and bent down so that its end could convenientlv be 

 immersed an inch or two under the surface of the water. The 

 end of this pipe was closed by a thin disc of copper, in which 

 a cncular hole was made ,-i|i-th of an inch diameter, through 

 which the steam from the boiler was blown into the cold 

 water. The water which received the heat was contained in 

 a tinned n-on vessel that weighed 3-77 lbs., and its capacity for 

 lieat may therefore be called equivalent to i lb, of water. In 

 each of the experiments, the water employed to receive the 

 steam weighed 28 lbs., to which, in the following table, re- 

 cording the principal facts, is added this i lb., in lieu of the 

 vessel. 



If either of the equations above be applied here to the facts 

 noted 111 this table, tlie sum of the latent and sensible heat will 

 come out 1119', 1190° and 1228°; and the latent heat 890°, 

 920 and 933 . It was observed, however, that the tin vessel 

 lost heat to die surrounding air very sensibly, and an experi- 

 ment was made to determine theamount of this effiict; and it 



