ON METHODS OF DETERMLNING THE DRYNESS OF STEAM. 



li: 



kind care accurate enough to prove that the specific heat varies. On the 

 other hand, Mr. Barrus has neglected to calculate the dryness fraction of 

 the steam, and so has missed the striking evidence these results afford to 

 the general accuracy of the instrument. The separator was not a very 

 perfect one, and allowed about 0-4 per cent, of moisture to pass. But the 

 separator results cannot be much wrong, for they are measured results 

 depending on no assumed constants. The error in calculating the 0-4 per 

 cent, passing the separator cannot be large enough to much affect the total 

 i-esult. On the other hand, the calculation from the heat gauge when the 

 separator was cut out, which depends on the assumed value 0-48 of the 

 specific heat and on the theory of the instrument, agrees strikingly viiih 

 the separator results. 



Test of Wire-draioing and Sejmrating Calorimeter combined. — The 

 following tests have been arranged to determine how far it is true, as 

 stated by Carpenter, that a separator traps the whole of the moisture, 

 even Avith very moist steam. The Barrus calorimeter was used with its 

 drip box or separator. The amount of water deposited in the drip box 

 was measured. Observations also were taken of the temperatures in the 

 two chambers of the wire-drawing part of the instrument. Let «,«o be 

 the temperatures in the first and second chambers of the wire-drawing 

 part, <3 the saturation temperature of steam in the second chamber 

 calculated from the pressure. Then, from the formula given above, 



__ 1116-<i— Q-] 9^3 + 048^ 

 ^~ 1116-0-71«i 



The dryness in each experiment has been calculated by this formula for 

 the steam passing from the drip box into the wire-drawing part. 



Tests of Barrus Calorimeter ivith Separator attached at the Central 



Technical College. 



It will be seen that, although the steam entered the separator with 

 more than 4-4 to 9 per cent, of moisture, the steam passing through the 

 wire-drawing part had only from 0-4 to 0-2 per cent, of moisture. The 

 mean dryness fraction of the steam passing to the second chamber in 

 the six tests was 0-997, so that the error of using the separator without 



