Chemistry and Physics. 53 
| Jet index. 
No.) Source of Cymene. Temp. | Sp. gr. A) Dy 
| 
1 |Cumin 16° |0°8569/1°4819}1 49011 5173 
2 Preexisting i in ins rs Suse 6° |0°8555/1°4775'1°4851)1°5111 
1 
3 | e,.---|16° |0°8630)1°4799/1-4876/1°5145 
4) From hesperidene ‘dibromide) I, 13° |0°8605/1°4835|1-4916/1°5196 
IL 15 
5 es : 5° |0°8638)1:4834)1 *4909'1 5187 
6 es camphor, by Eig 8) Ppalseies 16° 0°8621 1 4852/1 1:4935)1 5218 
si teed myristicol, by ae ~--|14°5° |0°8424/1°4706 1:-4776/1°5021 
Bie PUL .255 2: 13° l0- 8620 1 4815/1 -4888/1°5172} 
From these experimental data, the following values ma 
ew the specific refractive energy and refra actonegelrsas 
being deduced for the e A, and the specific dinperdon n being the 
difference between the Samer yp refractive energies for A and i 
Nuieber.:. PPesee eke" Dapeein  beaummaree al * 
1 5623 0-0414 75°3 
2 0°5581 0-0393 14:7 
3 *B561 00401 74:5 
4 0°5619 070419 75:3 
5 075596 00409 75-0 
6 0°5628 070424 15-4 
A 0.5586 0-0374 74°8 
8 075596 0°0404 75-0 
These results Gladstone regards as practically ea and as 
giving the mean optical data for cymene, as follows :— 
Specific refractive energy,..-. ..-.------------ 0°5599 
Specie dispersion. .4....... 4. .1- 005 6 see ce 0°0405 
Refraction-equivalent, PS OTE a eR ye 75°0 
In 1870, Gladstone —— attention to the fact that those aromatic 
hyd rocarbons and their derivatives which had been optically 
examined gave paces cat higher by six or eight than 
the f Bard ab number. Since all these bodies have a high dis- 
pe 
hot belonging in this group; and if so ssi acy will it retard 
light similai ly ? e prod tion of cym camphor, from 
hesperidene and from myristicol by ht, answers the 
4 polarized ray; but the author thinks this of slight moment, 
believing this property to be dependent not upon composition, 
ut upon peculiar internal structure. Refractive pest ena, 
