of the Interrupted S]iectra of Gases. 



45 



Table I. — Positions of 31 lines of the absorption -spectrum of 

 Chlorochromic Anhydride. 



No. of 

 line. 



Observed 



positions 



in air. 



Corre- 

 sponding 

 positions 



Calcu- 

 lated 

 positions 



Differ- 

 ences. 



No. of 

 line. 



Observed 

 positions 

 in air. 



Corre- 

 sponding 

 positions 



Calcu- 

 lated 

 positions 



Differ- 

 ence s . 







in vacuo. 



in vacuo. 









in vacuo. 



in vacuo. 



4-0-2 



0. 



16975 



1697-0 



1697-3 



-0-3 



60. 



18600 



1859-5 



1859-3 



5. 



17117 



17112 



1710-8 



+0-4 



61. 



18620 



1861-5 



18620 



-0-5 



10. 



17245 



1724 



1724-3 



-03 



63. 



18678 



1867-3 



1867-4 



-01 



15. 



1738-7 



17382 



1737-8 



+0-4 



66. 



18761 



1875-6 



1875-5 



+0-1 



20. 



1752-2 



1751-7 



1751-3 



+0-4 



C8. 



1881-3 



1880-8 



1880-9 



-01 



25. 



17660 



17655 



1764-8 



4-0-7 



71. 



1889-7 



1889-2 



1889-0 



+0-2 



28. 



17740 



1773-5 



1772-9 



+0-6 



74, 



1897-9 



1897-4 



1897-1 



4-0-3 



30. 



1779-1 



1778-6 



17783 



+0 3 



76. 



1902-6 



1902 1 



1902-5 



-0-4 



3.X 



17871 



1786-6 



1786-4 



4-0-2 



79. 



1911-5 



1911-0 



1910-6 



+0-4 



36. 



17941 



1793-6 



1794-5 



-0-9 



81. 



1916-2 



19157 



1916-0 



-0-3 



40. 



1805-5 



1805-0 



1805-3 



-0-3 



84. 



1924-5 



19240 



19241 



-01 



45. 



1818-9 



1818-4 



1818-8 



-0-4 



89. 



1937-5 



1937-0 



1937-6 



-0-6 



50. 



1832-4 



1831-9 



1832-3 



-0-4 



92. 



1946-5 



19460 



1945-7 



+0-3 



53. 



1840-2 



1839-7 



1840-4 



-0-7 



97. 



1960-4 



1959-8 



1959-2 



40-6 



55. 



1815-5 



18450 



1845-8 



-08 



105. 



1980-7 



19801 



1980-8 



-0-7 



58. 



1853-7 



1853-2 



1S53-9 -0-7 



1 











The outstanding differences fall within the limits of the errors 

 of observation and interpolation. Our theory is therefore verified 

 in the case of chlorochromic anhydride. 



8. The interval between two consecutive lines, which we used 

 in calculating column 4, was 2*70 scaleins, or units of our scale. 

 This value cannot be in error more than one five-hundredth part, 

 Hence the periodic time of the parent motion in the molecules 

 of chlorochromic anhydride, from which all these lines have pro- 



cceded, is within one five-hundredth part of — , t having the 



<v / 



signification already assigned to it. 



9. Having ascertained k, or the interval between two consecu- 

 tive lines, we may by equation (1) determine n, or the number 

 of the harmonic. Thus, if the inverse wave-length of our zero- 

 line be 1697*3, and if k be nearly 2*7, n+l must be an integer 



1697*3 

 which is nearly = — = 628*6. The only possible values are 



627, 628, 629, and 630, since any other integers would carry us 

 beyond the errors of observation. And when the measures shall 

 have been made with sufficient accuracy to decide which of these 

 numbers is the true one, it will in turn be possible to fix the 

 value of k with great precision. Thus, if, as is most probable, 

 our zero-line is the 628th harmonic, and if its inverse wave- 

 length in vacuo is 1697*3, then by equation (1) will 



1697-3 



k= 



629 



=■=2*6981, 



(3) 



