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‘= iydroaramatic - ‘alcbhols. Rie addition, these me areal are often highly hygroscopic 
ae and ‘small quantities of moisture may already hinder congealing. In order to dry these 
¥ alcohols, dry hydrogen had frequently to be passed through them for hours. If the 
substances were uniformly heated at the same time, the density increased regularly 
___ in some cases, and it was not always possible to arrive at any final stage. This was 
-__ specially noticeable with 1-methylcyclohexanol-3, when, with the increasing density, the 
, _ originally normal values of the molecular refraction sank lower and lower. It seems — 
3 that these alcohols, on being dried sharply and for some considerable time, undergo 
3 a chemical change, regarding the nature of which nothing can be said so far. As to 
the preparation of unsaturated hydrocarbons from these carbinols, the treatment with 
phosphorus pentoxide is to be recommended for secondary, that with potassium 
hydrogensulphate, for tertiary alcohols. Sometimes, however, potassium hydrogen 
sulphate acts polymerizing and should then be replaced by oxalic acid. 
The second publication bears the title, “On the Relationship between constitution 
and physical properties of isomeric and homologous hydroaromatic compounds”. The 
following laws have been established: 1. The boiling point of saturated alcohols and 
ketones sinks with the approximation of methyl to the hydroxyl and ketone groups, | 
whereas that of singly unsaturated hydrocarbons rises when methyl joins the double 
bond. The position of the methyl groups to one another only acts a secondary part, 
in comparison. According to the indications made hitherto, there are no distinct rules _— 
recognizable with certainty as to the boiling points of saturated hydrocarbons; this ° 
may, however, be due only to the defectiveness of the observations. 2. The density 
increases, generally speaking, in all the four classes of bodies, as the methyl groups 
go more closely together in the molecules and these approximate a double bond or 
a hydroxyl or carbonyl group. 3. Similar relations exist between constitution and 
refractive index, but they are not so pronounced. 4. The molecular refraction of iso-— 
merides of all the four classes is the greater, the farther the side chains are apart — 
and away from either the double bond or the oxygenous component. 5. The molecular — 
dispersion is normal for all the saturated or endocyclically unsaturated compounds, 
so that it is also the same for the isomerides, within a certain margin. 6. In direct 
Opposition to the rules given are the properties of the 1,1-dimethylcyclohexanol-4 and 
the corresponding ketone, for both substances have, in addition to high boiling points 
(which is according to the rule), a remarkably great density and refractive index, whereas 
middling or low values would have to be expected. It remains to be ascertained whether 
compounds with a gem.-dialkyl in para position generally make such an exception with 
regard to their constants. 7. Methene derivatives have lower boiling points and are 
less dense than isomerides with endocyclic double bonds, but have approximately the 
same refractive index. . 
Above rules apply in the first instance to once ond twice methylated compounds. 
As to the bodies substituted to a higher degree, reliable material is partly wanting 
and, besides, the differences between the isomerides seem to be somewhat lessened 
owing to the complicated conditions and the thus created different influences. 
In cyclohexanes and cyclohexenes, the entrance of methyl regularly causes the b. p. 
to rise, although it does not seem to be excluded altogether that in homologues, built 
up in very dissimilar form, the boiling points may almost coincide or that the higher 
homologue may boil at a lower temperature. This is often the case in cyclohexanols — 
and cyclohexanones. It is readily understandable that the density of oxygenous sub- 
stances sinks with the number of methyl groups entered and it is confirmed with regard 
to hydroaromatic alcohols and ketones. In cyclohexenes, the methyl groups generally 
