220 



mined from the two e(|iuiliüiis (or dilfcrent values for D, and the 

 in-oihicts are joined in die foUowin^ tal)les. yM^(-S') is then calcnhited 

 from Schalkwijk's equation with 3 virial coefficients; PV {P) from 

 our provisional equation. 



D 



PV{S) 



PV(P) (P)-(S) 



100 

 200 

 300 

 400 

 500 

 600 

 700 

 800 

 900 



—0.0006 

 —0.0030 

 -0.0048 

 —0.0020 

 +0.0110 

 + 0.0415 

 +0.0980 

 +0.1912 

 +0.3329 



The deviations found in this waj' from whatfollow^s from Schalkwijk's 

 equation with the extrapolations from our provisional equation 

 appeared to be surprisingly small. Only at a density' 100 or P^ ± 115 

 atmosphere pressure the ditfei'ence is greater than 1 per 2000, but this 

 is far outside the region of Schalkwijk's observations. At Z) =: 200 

 or /-*= ± 250 alms, the difference becomes 1 per 400. Later on it 

 dindnishes again, and takes opposite sign, but D = 500 or P = dtz 800 

 atms. lies again outside the region of our series of observations. 



In connection with the mutual correspondence of the series of 

 observations, the possibility of an agreement with Schalkwijk has 

 appeared from this. 



In order to be able to compare the 7 series of observations inter 

 se, and judge at the same time about the agreement with Schalkwijk, 

 we iiave reduced the 7 empiric equations in such a way that they 

 give PV= L.3573 for J) = 300. This is then in agreement with 

 the above table. Then the equations become: 



I PI/= 1.06625 + 0.0373496i) + 0.0^750091)2 + 0.0,, ,69144 04. s'g Nov. 1912. 



II PF= 1.06917 + 0. 0371540Z) + 0.0ö72697D24_0. 0,299111 Z)4. 21 Nov. 1912. 



III PK^- 1.07375 + 0. 0^66523 Z) + 0.0ö87561 i)2_j_o.0i. 64295 Z)4. h;,, Dec. 1912. 



IV PF= 1.06990 + 0.0j68353£) + 0.0085981 Z)2 4- 0.0, 202047 Z)4. lo'pebr. 1913. 



V PF=r 1.06893 + 0.036P806Z)- f 0.068 1640 Z)2 + 0.0, 268826 Z)i. i"/,a Febr 1913. 



VI P^'^ 1.05753 + 0.0374726/) + 0.0677437 £>2 + O.Oi263400Z)4. 22,24 April 1913. 



VII PF= 1.07341 +0.0j67205Z) + 0.0685024Z)2 + 0.0,264632£>i. 4 June 1913. 



