"He kept this spirit in the bladders a considerable time, and endeavoured several ways to condense it, but in vain. And when he wished to amuse his friends, he would take one of the bladders, and pricking a hole with a pin, and compressing gently the bladder near the flame of a candle till it once took fire, it would then continue flaming till all the spirit was compressed out of the bladder."[1]
The Rev. Stephen Hales, D.D., Rector of Farringdon, Hants, was the author of a book entitled _Statical Essays, containing Vegetable Staticks_, printed in 1726-27, and of which the third edition bears the date 1738. At p. 182 of this work, after a previous description of the destructive distillation of all kinds of substances in iron or other retorts, he says--
"By the same means also I found plenty of air [gas] might be obtained from minerals. Half a cubick inch, or 158 grains of Newcastle coal, yielded in distillation 180 cubick inches of air [gas], which arose very fast from the coal, especially while the yellowish fumes ascended."
Still later, viz. about 1767, we have the Rev. R. Watson, D.D., Regius Professor of Divinity in the University of Cambridge, and Bishop of Llandaff, interesting himself in chemistry. He wrote a series of _Chemical Essays_, one of which is entitled, _Of Pit Coal_, and in this he describes the production from coal (by destructive distillation) of illuminating gas, ammonia-water, tar, and coke. He further compares the relative quantities of the different products from various kinds of coal, but he appears to have been chiefly interested in the tar, and disregarded the gas and other products. Not the least interesting part of his book is the preface, in which he apologizes for his pursuits in the following words--
"Divines, I hope, will forgive me if I have stolen a few hours, not, I trust, from the duties of my office, but certainly from the studies of my profession, and employed them in the cultivation of natural philosophy. I could plead in my defence, the example of some of the greatest characters that ever adorned either this University or the Church of England."
This is quoted from the 5th edition, dated 1789, the essay on coal being in the second of five volumes. As the learned bishop published other works on chemistry, we may suppose that the forgiveness which he asks from his brother divines was duly accorded.