[219] Stahl, taking up the obscure notions of Becher and Van Helmont, supposed the phenomena of combustion to be due to phlogiston. He imagined that by combination with phlogiston, a body was rendered combustible, and that its disengagement occasioned combustion, and after its evolution there remained either an acid or an earth: thus sulphur was, by this theory, supposed to be composed of phlogiston and sulphuric acid, and lead of the calx of lead and phlogiston, &c. [220] Being called upon by the Solicitor for the Admiralty to examine into the causes of the fire which destroyed the _Imogene_ and _Talavera_, in Devonport Arsenal, I discovered a bin under the roofing which covered these ships, in which there had been accumulating for a long period all the refuse of the wheelwrights’ and painters’ shop; and it was quite evident that spontaneous combustion had taken place in the mass of oiled oakum, sawdust, anti-attrition, and old sail-cloth, there allowed to accumulate. [221] _Researches on Flame_: Sir H. Davy’s Collected Works. [222] See note, _ante_, _On the Chemical Theory of Respiration_. [223] At the request of the British Association, a committee undertook the investigation of this subject. Experiments were carried on by Dr. Daubeny, in the Botanic Gardens at Oxford, and by the Author, at his residence, Stockwell. Dr. Daubeny, in his report made at the meeting of the British Association at Birmingham, appears disposed to consider ten per cent. of carbonic acid in excess as destructive to the growth of ferns. I found, however, that, by gradually increasing the quantity, the ferns would live in an atmosphere still more highly charged with carbonic acid. [224] See memoir _On the Pilchard_, by Mr. Couch, in the Reports of the Royal Cornwall Polytechnic Society.