Royal Society. 69 



a length commensurate to our wishes, but splendid and useful to the 

 utmost expectation of his warmest Iriends. 



Another distinguished member of this Society has recently been 

 taken from us, by one of those accidents, common indeed to old age, 

 yet of a nature to excite compassion, or feelings perhaps of a stronger 

 cast. Dr. George Pearson was elected in June 1791, and he has en- 

 riched our Transactions with ten communications. The first, in the 

 year of his admission, on Dr. James's antimonial powders. The com- 

 position of this celebrated febrifuge having been long withholden from 

 the public, notwithstanding the sworn specification of its inventor, 

 a great anxiety was naturally felt for discovering the secret. This, 

 Dr. Pearson effected, having proved by analysis, and by the reunion 

 of the constituent parts, that antimony and phosphate of lime made 

 up the whole mass. Some slight differences may still exist between 

 the concealed medicine and any other that can be produced, arising 

 probably from peculiar, amlpossibly accidental and unimportant ma- 

 nipulations ; but no doubt can be entertained as to the essential in- 

 gredients. The second, in 1792, on the composition of fixed air. 

 The third, in 1794, on a peculiar vegetable substance, imported from 

 China. The fourth, in 179o, on the nature and properties of wootz, 

 iron and steel made in the East Indies. The fifth, in 1796, is a paper 

 equally interesting to the natural philosopher and to the antiquary, 

 since it ascertains the composition of metallic weapons belonging to 

 times the most remote, and confirms the opinion, derived from clas- 

 sical authority, of their being made from an alloy of copper and tin. 

 The sixth, in 1797, on the nature of gas, produced by passing electric 

 sparks through water. This communication must be highly estimated, 

 since it tended, at that early period, strongly to confirm the great 

 discovery of Mr. Cavendish — the decomposition of water ; a disco- 

 very of the utmost importance, but requiring every jiossible confir- 

 mation, as it went in direct opposition to the decided opinions, to tiie 

 prejudices of many thousand years. We are become familiar with hy- 

 drogen, with oxygen, with the compound nature of liquids, and the 

 changes of form produced on bodies by the agency of heat. The spe- 

 culative philosophers of antiquity, on the contrary, mistaking varie- 

 ties of form for real differences of substance, arranged all physical 

 nature under four classes, denominating solid bodies, or the principle 

 of solidity, earth ; liquid bodies, under a similar hypothesis, water ; 

 and the principle of elasticity, air ; fire, or heat, occupied the fourth 

 division : and to these was added a fifth, or quintessence, — the sub- 

 stance endowed with consciousness, with thought, and with the power 

 of originating motion. It is obvious that ice, water, and steam, to 

 satisfy this arrangement, must possess three distinct essences; yet 

 such is the ])ower of habitual attachment to opinions never belbre 

 questioned, that had Mr. Cavendish, the scientific ornament of our 

 country and of his age, lived some centuries before our time, he might 

 perhaps have experienced a common fate with the ))hilosopher who 

 maintained the revolution of the earth and the central ])osition of the 

 sun. The seventh, eighth, and ninth communications, in subsequent 

 years, are strictly professional; and the tenth, in 1825, also medicnl, 



relates 



