198 EXAMINATION OF A NAPHTHA FROM LIME-SOAP. 
Air remaining in balloon, . ‘ , i : @ F 3 ‘ » . ! i A ‘ Occ. 
Height of barometer, . .  . S Ose e mie oh iS akin ee SEN Hay 769.3mm. at 25° 
Density of vapor found, = Je . : i 2 ee . : : <6 A » 4.9166 
fe “ theoretical (C29 H20), - ‘ 3 x . 3 Z P ‘ . ‘ F 4.841 
Its sp. gr. was found to be 0.7912, at 0°. 
The fraction 165°-166° was treated at once with monohydrated sulphuric acid. The 
first portion of acid blackened very much, and heat was evolved, but no very great amount 
of viscid matter separated; the second portion of acid also blackened very much, but 
was unusually free from viscidity; the third portion acted much less than the second, and 
the fourth and fifth portions much less than the third, though considerable heat was 
evolved throughout. The hydro-carbon at last became strongly colored, and much sul- 
phurous acid was evolved. It was washed, dried, and boiled upon sodium in the usual 
way. 
On combustion, 0.2294 grm. of the hydro-carbon gave 0.285 grm. water, and 0.7264 
grm. carbonic acid, or 
Found. 
Carbon 86.36 
Hydrogen 13.77 
100.13 
These numbers give the empirical formula Cys Hh;.. 
Previous to the above-mentioned examination of the two extremities of this heap, 
but not until long after the heap itself had been obtained, an attempt was made to 
hasten operations by working upon it alone; the ten or twelve most prominent frac- 
tions of the heap having been selected and repeatedly redistilled, to the exclusion of all 
other fractions, both above and below, in the hope that products of nearly constant 
boiling point might thus be more quickly procured. At the commencement of this 
special operation the common difference between each of the fractions was about one 
degree, that is, at each successive distillation each of the fractions began to boil about 
one degree lower than it did in the preceding distillation, and the distillatory process 
was continued until this common difference had been reduced to one-third of one de- 
gree; the portions of distillate more volatile than the selected fraction of lowest boiling 
point, and of residue less volatile than the selected fraction of highest boiling point, be- 
ing meanwhile added to the fractions in the old series, now excluded from the distilla- 
tion, which had been taken off at similar temperatures. It may here be said that this 
operation was not found to be advantageous, and we do not in any way commend it, 
at least when applied, as above, to bodies which have already been brought to such a 
condition that their boiling points are tolerably constant. 
