348 HISTORY OF SCIENCE. 



period of nearly fifty years he continued to enrich the " Transactions" 

 with valuable papers on chemistry and on some departments of natural 

 philosophy. The accession to his large fortune did not alter Caven- 

 dish's simple habits of life. He had, in his youth, accustomed him- 

 self to the utmost regularity, and to his last day he never allowed this 

 regularity to be deranged. He attended the meetings of the Royal 

 Society with the greatest punctuality, and his appearance in it consti- 

 tuted the whole scene of his public life. The seclusion in which he 

 lived no doubt caused his name to be less widely known than his 

 scientific merits deserved, but his reputation has always been high 

 among the savans of Europe. Cavendish's first paper was a disserta- 

 tion on carbonic acid gas ; but his chemical renown rests mainly upon 

 his researches on hydrogen, the composition of water, that of nitrous 

 acid, and of atmospheric air. Unfortunately, Cavendish had been 

 brought up in the doctrines of the phlogistic school of philosophers, 

 and the prepossession of his mind with these ideas prevented him in 

 many cases from obtaining just inferences from his well-arranged ex- 

 periments. The authorship of the discovery of the true composition 

 of water has been claimed for several -chemists ; but the honour of this, 

 like that of many other great discoveries, must in justice be distributed 

 amongst the individuals who contributed the most important steps. 

 Among these were the preparation and the study of oxygen, for the 

 completion of which the several labours of Scheele, Priestley, and 

 Lavoisier were required. 



To whom belongs the merit of having first experimentally proved 

 the compound nature of water has been again and again the subject 

 of contention. It would be useless to enter here upon a discussion 

 of the various claims to priority which have severally been advanced 

 on behalf of Cavendish, Priestley, Watt, Lavoisier, and others ; we may, 

 however, notice some instances in which the fact was observed, but its 

 significance and importance not clearly appreciated, until Lavoisier had 

 distinctly declared the truth. 



PIERRE-JOSEPH MACQUER (171 1 1784), a French chemist, who 

 published a " Course of Chemistry " and a " Dictionary of Chemistry," 

 described in an edition of the latter work revised in 1781 an experiment 

 which really consisted in forming water from its elements ; but he did 

 not follow up the clue he had obtained by any further investigation 

 into the matter. As the experiment is instructive, interesting, and 

 simple, it is represented, together with a portrait of Macquer, Fig. 173 : 

 in it is seen a bottle containing diluted sulphuric acid and zinc, and 

 furnished with a bent tube, from the orifice of which the hydrogen 

 issues. The gas having been lighted, a cool porcelain saucer was held 

 near the flame, when the surface of the saucer became moist by a 

 deposit of drops of water. Macquer thus describes his experiment : 

 " I also assured myself, by placing a white porcelain saucer in the 

 flame of the inflammable gas which was burning quietly at the mouth 



