82 Major W. T. David on the Calculation of 



He has, however, two pairs o£ records for various mixture 

 strengths *, the one pair at 1 \ atmospheres density and the 

 other pair at \\ atmospheres density. Calculations from these 

 records give the information shown in Table III. 







Table III. 







D 



(atmospheres). 



Percent, strength 

 of mixture. 



fi 



max. 



Rip. 



1-24 





10-2 



1800 



0-7 



1-24 





12-2 



2250 



0-94 



1-50 





15-0 



2400 



1-17 



1-56 





10-0 



1840 



0-87 



The equation derived from the first pair at 1| atmospheres 

 density is 



R T = 0-00053 (<9 mas .- 480), .... (12) 



and that from the second pair at 1^ atmospheres density 

 (approximately) is 



Rt = 0-00053 ((9 max .- 190). . . . . (13) 



24. In considering these equations it must be remembered 

 that each is derived from two points only and the constants 

 are therefore not to be relied upon. They show fairly 

 definitely, however, that the greater the density the smaller 

 the constant within the brackets, and it would appear that 

 this constant is dependent upon the shape of the cooling 

 curve. 



25. An examination of the records for 15 per cent, mix- 

 tures shows that between the limits of density f atmosphere 

 and 1^ atmospheres R T and R,t vary approximately as \/D. 

 An approximate relationship between Rt, 0, and D is there- 

 fore given by 



R r = 0-00056 (6> max .- 700) s/T). . . . (14) t 



* Taken in position A. 



t The form of equations (12) and (13) indicates that it would have been 

 better to express equation (14) in the form K T = O-OOO55[0 mM . -700/(D)] 



where /(D) = ^ when D = l-24 or 1^ when D = l-53. Bat as has 



yv 700 700 



been stated equations (12) and (.3) have been derived from two pairs of 



