182 Dr. Schroeder van der Kolk on Gases. 



pressure, we have, in the first place, for 4° and 100° the formulae 

 given in the second paragraph ; the analogous formula may also 

 be calculated from the values of k at — 87° given in § III. From 

 the three values corresponding to the pressures 0*76, 1, and 2 

 metres, we get the formula 



£=[0-99749-A(A-l)+B(A-l) 2 ]K, 



A=0 0046808, log A =7-66846 -10, 



B = 0-00017608, logB = 6-24570-10, 



dk 



from which -j- may be deduced for —87°. 



Comparing this formula with the two corresponding to the 

 temperatures 4° and 100°, it appears that the values of A and 

 B, and therefore the variation from Mariotte and Gay-Lussac^s 

 law, are much greater at this lower temperature. 



c 1 — c may now easily be calculated for the pressures 0*76, 1, 

 and 2 metres, and between the temperatures —87° and 100°. 

 The formula is again 



C — c — 



'(<->£) 



For calculation this formula may be written in a more simple 

 torm. Putting A;=^K, where ^r is the variable in the value k } 

 and p = 13595 h, the formula becomes 



(♦H,*Yk 



Cj — c = 



For 4° C. and 0*76 metre pressure we have in the case of air, 

 for example, 



K= 29-2443, /*=076, 



+= 1-0002995, ^ = 00000060527, 



t=277-15, 



dyfr 



J=422-10, ^=-0-0012546, 



dh ' 



from which is obtained c } —c = 0-069470. In the calculation 

 Gausses addition and subtraction Tables were always used, as 

 given in Wittstein's Tables of Logarithms. 



The following Table was obtained for c x —c in the case of air: — 



