tarry matter, and with only a slight amount of separated carbon or
deposited soot.

The best mode of splitting up the paraffin oils, and the special
arrangements of the retort or distilling apparatus, also formed, he
said, an extensive inquiry by itself. In one set of trials the oil was
distilled into gaseous vapor, and then passed through the retort. In
another set of experiments, the oil was run into or allowed to trickle
into the retorts, while both modes of introducing the oil were tried
in retorts charged with red hot coke and in retorts free from coke.

Ultimately, it was found that the best results were obtained by the
more simple arrangement of employing iron retorts at a good cherry red
heat, and running in the oil as a thin stream direct into the retort,
so that it quickly impinged upon the red hot metal, and without the
intervention of any coke or other matter in the retorts. The paraffin
oils employed in the investigations were principally: (1) Crude
paraffin oil, being the oil obtained direct from the destructive
distillation of shale in retorts; (2) green paraffin oil, which is
yielded by distilling or re-running the crude paraffin oil, and
removing the lighter or more inflammable portion by fractional
distillation; and (3) blue paraffin oil, which is obtained by
rectifying the twice run oil with sulphuric acid and soda, and
distilling off the paraffin spirit, burning oil, and intermediate oil,
and freezing out the solid paraffin as paraffin scale. The best
practical trials were obtained in Pintsch's apparatus and in Keith's
apparatus.

After describing both of these, Dr. Macadam went on to give in great
detail the results obtained in splitting up blue paraffin oil into gas
in each apparatus. He then said that these experimental results
demonstrated that Pintsch's apparatus yielded from the gallon of oil
in one case 90.70 cubic feet of gas of 62.50 candle power, and in the
second case 103.36 cubic feet of 59.15 candle gas, or an average of
97.03 cubic feet of 60.82 candle power gas.

In both cases, the firing of the retorts was moderate, though in the
second trial greater care was taken to secure uniformity of heat, and
the oil was run in more slowly, so that there was more thorough
splitting up of the oil into permanent gas. The gas obtained in the
two trials was of high quality, owing to its containing a large
percentage of heavy hydrocarbons, of which there were, respectively,
39.25 and 37.15 per