

of Molecular Refraction a 



nd Dispersion. 



2C 



Speci- 

 men. 



Temp. 

 0. 



Sp. Gr. 



/v 



/v 



*v 



V 



*V 



/v 



V 



I.... 



22 



1-460 



1-5026 



1-5076 



1-5096 



1-5180 



1-5289 





II.... 



155 



1-4705 



1-5063 



1-5117 



1-5146 



1-5224 



1-5329 







II. ... 



134 



1-474 



1-5071 



... 1 1-5230 



... 



1-5446 



1-5650 



From these observations we obtain the following molecular 



refraction, ~—r P=-R. 



7 a 



Speci- 

 men. 



\' 



R . 



B 



E C 



R . 



R E - 



R . 



p 



R o' 



I 



6747 



68-14 



68-41 



6954 



71-00 







II 



67-48 



68-20 



68-59 



69-63 



71-03 







II 



6743 







69-54 





72-42 



75-13 





It is evident that in the iron compound also the refraction 

 and dispersion are very great. The molecular refraction 

 for the line a of hydrogen may be assumed at 68*5, and the 

 molecular dispersion between the lines 7 and a of hydrogen 

 at b'*6. If we reckon for the lines A and H, we may assume 

 H would be about 78*0, which would give a molecular dis- 

 persion between these limits of about 10*5. 



In discussing their observations, Messrs. Mond and Nasini, 

 assuming that CO has a molecular refraction of 8*4, reckoned 

 the atomic refraction of nickel at 24" 1, instead of 9'9, which 

 I had assigned to this element in solutions of its salts, and 

 which subsequently has been fairly corroborated by Nasini's 

 own experiments. This difference they attributed to a dif- 

 ference of valency in the metal. By parity of reasoning the 

 atomic refraction of iron for the line C would be 26*5, or 

 25*5 for the line A, instead of 11*6 previously determined for 

 bivalent iron from solutions of its salts. 



But this involves the assumption that CO in these carbonyls 

 has the same value as we should expect to find in an organic 

 substance. It also assumes that the nickel has 8 valencies, 

 while the iron has 10, in the above-named compounds, and 



7 

 that iron has presumably - indiferrohepta-carbonyl; and that 



