John Platts, The Book of Curiosities
“ In clear weather, it does not bubble above two or three feet. People make cisterns near the springs, into which they convey what overflows by troughs, taking off the naphtha from the surface, under which there is a mixture of water, or some other heavier fluid. The greater part is of a [Pg 493] dark gray colour, very unpleasant to the smell, but used in lamps by the poorer sort. There are also springs of black naphtha, which is thick, and in distillation grows not clear, but yellow ”
