( 608 ) 



ment of' hxj jt in jiscciidiiii^- jxiwers of 7'--' tlie secuiid power*}. 

 While for the other teinpemtiires in the table iiieiitioiied the devititioiis 

 did not exceed O.Ol atni., a deviation of Obs. — Comp. =z 0.05 atm. 

 was found for 30°. 82 C. '). Althongh it was then iield probable that 

 this deviation was to be ascribed to an accidental error of observation, 

 we have afterwards found that a deviation iji the same sense and 

 of abont the same size also occurs in the results of other observers 

 abonr saturated vapour pressures of carbon dioxide near the critical 

 point. 



A comparison of the results of Brinkman's observations (Thesis 

 Amsterdam 1904: pp. 41 and 42) of saturated vapour pressures of 

 methyl chloride and carbon dioxide with the pressures derixed by 

 him according' to a formula of the same form as the one mentioned 

 above, yields the following differences : 

 foi- methyl chloride (^'z, = 143.'12) : 



at /=:137.°54, 138.°92, 140.°26, 141.^66, 142.^02 

 U—(J= + 0.02, — 0.01, — 0.02, + 0.03, -f 0.08 ; 

 for carbon dioxide (/^=3J.°12): 



at ^ = 24.^24, 2()."08, 28.^4ti, 29.-^86, 30-^40 

 0—6'= + 0.02, —0.02, +0.03, +0.08, +0.07. 



In both substances investigated one finds below the critical tempe- 

 rature an obvions deviation resembling that found in Comm. N". 88. 



The observations of Am.\gat, Journ. de ])hys. (2) 1 (1892) p. 288, 

 of the saturated vapour pressure of carbon dioxide fail to gi\e any 

 definite indication about the question treated here because Amagat 

 has I'ounded off the pressures to 0.1 atm. In comiection with the 

 preceding statements, however, it desei-ves attention that Tsuruta, 

 Journ. de phys. (3) 2 (1893) p. 272, when comparing these data 

 with the formula /> = 34.3 + 0.8739/ + 0.01135r^ also there found 

 an obvious ditference (^ — 6' at 31. '^25 which exceeds by 0.06 atm. 

 that at 31. ''35 (crit. temp, according to Amagat). 



From the data mentioned hei-e one might draw the conclusion 

 that for carbon dioxide and methyl chloride the curve of the saturated 

 vapour |)ressures, continued to near the critical j)oint, with extrapo- 

 lation to this point would lead us to expect a pi- somewhat larger 

 than the critical pressure found experimentally. From the very careful 



ij in Physik. ZS. 8 (1907) p. 944, Bose went sliil farther and kept tiie third 

 power in this development wliicli had been given by Rankine, Misc. Scientif. 

 Papers pp. 1 and 410, 



~) As it appears from the columns Obs. and Comp. all the numbers in the column 

 0. — C'. have wrong sigus. 



