illuminating agents over vegetable and animal oils, alike for
lighthouse and ordinary house service.

The later trials were mainly concerned with the breaking up of the
paraffin oils into permanent illuminating gas. Experiments were made
at low heats, medium heats, and high heats, which proved that,
according to the respective qualities of the paraffin oils employed in
the trials, there was more or less tendency at the lower heats to
distill oil instead of permanent gas, while at the high heats there
was a liability to decarbonize the oil and gas, and to obtain a thin
gas of comparatively small illuminating power. When, however, a good
cherry red heat was maintained, the oils split up in large proportion
into permanent gas of high illuminating quality, accompanied by little
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