in the Velocity of Propagatian of Light in Water. 357 



of other bodies, because it may, within narrow limits, be obtained 

 almost chemically pure. Moreover Kremers* and Matthiessenf 

 have proved that small mixtures of salts do not appreciably alter 

 the constants of expansion of water. 



In my experiments I used distilled water out of Professor 

 Kolbe's chemical laboratory, and I distilled it frequently myself 

 with every care. For every separate determination, moreover, 

 the absorbed air was expelled by continual boiling. 



We may here introduce a scheme showing some numerical 

 values for the relation given between the velocity of propagation 

 of light and the density. 



A signifies the constant term in Cauchy's dispersion-formula, 

 D is the density, wh is the index of refraction for Fraunhofer's 

 line H. (See Gladstone and Dale, Phil. Trans, vol. cliii. pp. 321 

 & 322.) 



Substance. 



Temp. 



Volume. 



A. 



A-l 

 D ' 



wh-1 

 D ' 



A 2 -l 

 D * 



Differ- 

 ence. 



Sulphide of carbon < 

 Extreme difference. . . 



o 



22-5 

 36-5 



25-5 



0-9554 



0-9685 

 09854 



+00300 



1-5960 

 1-5865 

 1-5753 



-0-0207 



0-5694 

 0-5680 

 0-5668 



-0 0025 



0-5930 

 0-5923 

 0-5916 



-00014 



1-4782 

 1-4714 

 1-4599 



-0 0183 



-68 

 -15 



Water \ 



1 

 15-5 

 27-5 



48-0 



47 



0-9999 

 10007 

 10034 

 10109 



+0-0110 



1-3227 

 1-3228 

 1-3216 

 13193 



-00035 



03227 

 0-3230 

 03227 

 0-3227 



-0-0003 



0-3300 

 0-3300 

 0-3300 

 0-3295 



-00005 



0-7495 

 0-7497 

 0-7492 



0-7486 



-00009 



+ 2 



- 5 



- 6 



Extreme difference... 



Alcohol \ 





 20 



40 

 60 



40 



0-9132 

 0-9326 

 0-9324 

 09762 



+00630 



1-3598 

 1-3518 

 1-3435 

 1-3347 



-00251 



0-3286 

 0-2518 

 00435 

 0-3347 



-0-0014 



0-3480 

 0-3478 

 0-3473 

 0-3473 



-0-0007 



0-7754 

 0-7716 

 0-7675 

 0-7628 



-0 0126 



-38 

 -41 

 -47 



Extreme difference. . . 



Formiate of ethyle, J 

 C^HC^OC 2 1 



Extreme difference. . . 



22 

 31 

 40 



18 



10305 

 10436 

 10573 



+00268 



1-3476 

 13434 



1-3390 



-00086 



0-3582 

 0-3584 

 0-3584 



+0-0002 



0-3607 

 0-3611 

 0-3615 



+0-0008 



0-8409 

 0-8397 

 0-8389 



-0-0026 



-12 

 -14 



Benzole \ 



10-5 

 23 



39 



28-5 



10125 

 1-0228 

 1-0481 



+00356 



1-4777 

 1-4704 

 1-4601 



-00176 



0-4836 

 0-4834 

 0-4822 



-0-0014 



0-5371 

 05370 

 0-5353 



-0-0018 



1-1999 

 11944 

 1-1863 



-0-0127 



-46 



-81 



Extreme difference. . . 



Ann. vol. cxiv. p. 41. 

 t Pogg. Ann, vol. cxxviii. pp. 512-540. Report of British Association, 

 1863, p. 37. 



Phil. Mag. S. 4. Vol. 35. No. 238. May 1868. 2 B 



