It has been long considered a very energetic poison, and it would, at the same time, appear to be a very insidious one; for sensibility is quickly destroyed by it, without any previous suffering. We are acquainted with a chemist who was suddenly deprived of sense, as he stood over a pneumatic trough, in which he was collecting the gas. It would seem to act upon the nervous system through the medium of the blood, in which it is extremely soluble. It constitutes the particular gas of privies, and is the immediate cause of those accidents which we have already described in a former part of this work, _vol._ 1, _page_ 100; since the printing of which we have heard of the death of four persons from emptying a privy at Brompton. This gas will be sometimes developed during the imperfect combustion of wet coals[504]; and it was probably owing to its presence, or to that of _carburetted hydrogen_, that the accident arose which is recorded by _Mr. Sutleffe_ in the _Medical Repository_. “He was hastily summoned to a neighbouring family at bed-time, where he found a female domestic labouring under a shrill, laborious inspiration; she had taken up from a good kitchen fire, a panful of live coals, from which a sudden suffocating blast seized her.” CARBURETTED HYDROGEN GAS. This gas is developed by several chemical processes. We have just stated that if, during the burning of charcoal, moisture be present, it is evolved in abundance. It appears to be particularly fatal to animal life. _Dr. Beddoes_ made many experiments upon the subject, from which it would seem to destroy life by rendering the muscular fibre inirritable without producing any previous excitement. In order to decide this question, _Sir Humphry Davy_[505] ventured to take three inspirations of the gas produced from the decomposition of water by charcoal. “The first inspiration produced a sort of numbness and loss of feeling in the chest, and about the pectoral muscles; after the second,” says he, “I lost all power of perceiving external things, and had no distinct sensation, except a terrible oppression on the chest; during the third expiration, this feeling disappeared; I seemed sinking into annihilation, and had just power enough to drop the mouth-piece from my unclosed lips. There is every reason to believe, that if I had taken four or five inspirations, instead of three, they would have destroyed life immediately, without producing any painful sensation.” CHLORINE—_Oxy-muriatic Acid Gas_.