186 EXAMINATION OF A NAPHTHA FROM LIME-SOAP. 
of the hydro-carbon had distilled over, the thermometer in the retort rapidly rose to 
above its upper limit, 120°, the liquid in the retort became black, and sulphurous acid 
was evolved. The distillation was at once interrupted and the residue put aside. The 
distillate, being now repeatedly redistilled over sodium, came over clear at 79.5° (cor- 
rected). For an analysis of this sample, see below, No. III. . 
A second portion of the product resulting from the treatment with diluted acid 
having been treated, as above, with monohydrated sulphuric acid, the first distillation 
over sodium was now more carefully watched than before. The retort being heated 
with a small flame, its contents distilled over freely at first, and without coloration, at 
79°; after a while the temperature of the retort rose slowly, and at 87° scarcely 
anything came over. At this point the distillation was stopped, the liquid in the retort 
being quite oily, though still light-colored. On redistilling the distillate, upon sodium, 
it came off at 79.9° (corrected). 
The bottle containing the product (No. III.) resulting from the treatment with mono- 
hydrated acid, was now immersed in a mixture of ice and salt until the moment when 
erystals began to form, when it was quickly removed and the still liquid portion of the 
hydro-carbon poured off, the bottle being inverted and the crystals allowed to drain as 
they melted until only a comparatively small portion of the solid remained. This last 
was then subjected to analysis; see below, No. IV. 
The quantity of material at our disposal being small, we were unable to carry out 
any systematic course of purification by crystallization, and a single operation like the 
preceding could hardly be expected to augment the purity of our product to any great 
extent. But the tendency of this experiment is none the less worthy of being noted ; 
its result still pots in the direction indicated by the preceding trials. Each step in 
the series of treatments above recorded brings us a little nearer to the pure benzole of 
which, as we have ourselves no doubt, the product (80°-81°), obtained by distillation, 
is mainly composed. 
I. As has already been stated, 0.2685 grm. of the unpurified hydro-carbon, obtained 
by distillation and fractional condensation, gave 0.2203 grm. water, and 0.8849 grm. 
carbonic acid. 
II. 0.1914 grm. of the hydrocarbon, after treatment with diluted acid, gave 0.1593 
grm. water, and 0.6386 grm. carbonic acid. 
IIT. 0.1485 grm. of the hydrocarbon, after treatment with monobydrated sulphuric 
acid, gave 0.113 grm. water, and 0.4985 grm. carbonic acid. 
IV. 0.1962 grm. of the hydrocarbon, after crystallization, gave 0.1484 grm. water, 
and 0.6631 grm. carbonic acid. Or 
