likewise ae the specific Betiy. if the substances comgaren are 
analogous way, but the contrary occurs pretty frequently with homologues f 
structure. As far as saturated hydrocarbons are concerned, the. difference in ig 
sities of the homologues is only small. ; 2 
No rules can be established concerning the refractive indexes of noma here a 
the constitutive influences preponderate completely. The observations already made 
have been collected by von Auwers, arranged and, to a great extent, calculated again. 
They had to be supplemented by determinations, meant to serve for checking previous 
indications, and by examinations of compounds of determinate constitution, which partly 
had to be prepared specially for the purpose. 
In order to calculate the refractive in- 
dexes for the normal temperature of 20°, the factor 0.00045 for 1° has been used, 
which is sufficiently accurate for all the cases under consideration. As to the specific _ 
gravities, it is not recommendable, however, to avail oneself of either of the-most 
frequently used constant factors of 0.0008 or 0.00093 for 1°, but 1/900 on an average 
for 1°, as proposed by Roth and Eisenlohr’). 
We beg to add a list of compounds investigated by the authors, but refrain from 
entering into details: 
cyclohexane . 
cyclohexene . : 
methenecyclohexane . 
1,3-dimethylcyclohexane 
1,2-dimethylcyclohexene-1 . 
1,3-dimethylcyclohexene-3 . 
1,3-dimethylcyclohexene-5 . 
*1,4-dimethylcyclohexene-1 . 
ethenecyclohexane 
1,3,5-trimethylcyclohexene . 
cyclohexanol 
1-methylcyclohexanol-1 
1-methylcyclohexanol-2 . 
1-methylcyclohexanol-3 . 
1-methylcyclohexanol-4 
1,3- rapihylayclobiexanol: 3 
1,4-dimethylcyclohexanol-4 
1,3-dimethylcyclohexanol-5 
1,3,5-trimethylcyclohexanol-5 . 
cyclopentanone . 
cyclohexanone . 
cycloheptanone . 
1 iwi ch eiasons2 
1-methylcyclohexanone-3 
1-methyleyclohexanone-4 
1,3-dimethyleyclohexanone-5 . 
Boiling point 
124 to 126° (760 mm.) 
126 to 127° (746 mm.) 
124 to 126° (751 mm.) 
136 to 136.4° (766 mm.) 
139 to 141° (766 mm.) 
1,3-dimethyl-5-methenecyclohexane 135 to 136° (744 mm.) 
. m.p. 23° 66 to 69° (15 mm.) 
56.5° (10 mm.) 
167.4 to 167.6° 
76 to 78° (14 mm.) 
74.7 to 75.2° (12 mm.) 
79 to 81° (21 mm.) 
70 to 72° (12 mm.) 
89° (16 mm.) 
83 to 85° (15 mm.) 
130.0 to 130.4° 
156.6 to 156.8° 
167° (740 mm.) 
60 to 60.2° (15 mm.) 
55.8 to 56.4° (10.5 mm.) 
70 to 72° (12 mm.) 
Density 
80 to 80.2° (749 mm.) d4¥3 0.7869 
83 to 83.5° (760 mm.) ds 0.8143 
102.5° (756 mm.) 
118 to 120° 
d= 0.8036 
d2° 0.7701 
d= 0.8315 
d= 0.7998 
d2t° 0.797 
d4° 0.7985 
d*22° 0.8239 
d° 0.7941 
d74* 0.7922 
d=S° 0.9463 
d%2° 0.9249 
d= 0.9333 
dS" 0.9179 
d5° 0.9183 
d™2° 0.9028 
d=2" 0.9060 
d*£4° 0.9004 
d*2° 0.8861 
d=" 0.9509 
d*°2° 0.9501 
d5° 0.9498. 
d 1510 0.9296 
d22" 0.9139 
d#4° 0.9119 
d#3° 0.8916 
1) Refraktrometrisches Hilfsbuch, Leipzig 1911, p. 76; Report April 1912, 150. 
Np 
1.43119 (10.859) - 
1.44921 (15,19) 
1.45092 (17.89) - 
1.42308 (22,0) 
1.46178 (13.59) 
1.44533 (22.49) 
1.44361 (21.1°) 
1.44373 (229) 
1.46389 (17.6°) 
1.44378 (24.7°) 
1.44628 (14.69) 
1.46560 (22.6°) 
1.45874 (24.65 Oy 
1.46585 (13.4°) 
1.45444 (24.3 °) 
1.45594 (20.7°) 
1.45414 (22.99) © 
1.45534 (23.99) 
1.45622 (18.4) 
1.45115 (24.79) 
1.43757 (17.89) 
1.45261 (15.39) 
1.46027 (21.99) 
1.45049 (14.69) | 
1.44313 (25. 159) 
1.44322 (24.4°) — 
1.44102 (24.59) = 
