439 



DALTON, JOHN. 



DAMASUS I. 



4EO 



1810, be treats of the elementary principles, or simple bodies, oxygen, 

 hydrogen, azote, carbon, sulphur, phosphorus, and the metals ; next 

 he treats of the oxygen combined with hydrogen, azote, carbon, sul- 

 phur, and phosphorus; and of hydrogen combined with nzote, carbon, 

 sulphur, and phosphorus; finally, he treats of the fixed alkalies and 

 earths. The table of atomic weights at the end of this volume, though 

 more complete than the one he had given at the end of the first 

 volume, is still very imperfect 



The atomic theory is undoubtedly one of the most important contri- 

 butions which has ever been made to chemistry; and hardly less 

 important were Daltou'a attempts to determine the atomic weights of 

 the different substances, though scarcely a single number was deter- 

 mined correctly. At the time when he made his discovery there was 

 not a single chemical analysis which could properly be considered as 

 correct ; there was not a single gas whose specific gravity was known 

 with any approach to accuracy ; and Dalton displayed infinite sagacity 

 at coming so near the truth as he did. Since the introduction of the 

 atomic theory, the knowledge of chemical combination has been siin- 

 plifi. d to an amazing extent, and the processes of analysis, which 

 constitute the essence of chemistry, have assumed a degree of accuracy 

 almost approaching to mathematical precision. Manufactures have 

 been benefited as well as science ; the quantity of each constituent of 

 any article can be regulated with perfect accuracy, so that there is 

 no waste, and the result of the combination can be reckoned upon 

 with unfailing certainty. 



Dalton represented his atoms by symbols, as, for instance, oxygen 

 by a circle, hydrogen by a circle with a dot, and other elements by 

 similar simple figures. He considers that all bodies are composed of 

 atoms, which, however small, have a definite size and weight The 

 symbols of oxygen and hydrogen placed together represented water, 

 which he supposed to be composed of an atom of each ; and other 

 symbols were used in a similar manner. The atomic weights are the 

 relative or combining weights, not the absolute weights. Assuming 

 hydrogen to be the lighte.it body he called it 1 ; oxygen he determined 

 to be 7, but it has since been ascertained to be 8. Dr. Wollastou has 

 called oxygen 1; hydrogen then becomes "125. Dalton not only stated 

 the general principle of combination in definite proportions, but he 

 stated the chief laws of combination on which modern chemical 

 analysis is based : 1, that the same compound consists invariably of 

 the same constituents ; 2, that the elements of every compound 

 always unite in the same proportion by weight (and Guy-Lussac, iu 

 1809, proved that gai-es unite in the same proportion by volume as 

 well as by weight) ; S, that, when any element combines in more pro- 

 portions than one, those proportions are multiples 1, 2, 3, 4; 6, 12, 

 18, 24 ; 8, 16, 24, 32, and so on ; 4, that, if two substances combine 

 in a certain proportion with a third, they combine in exactly the same 

 proportion with each other ; 5, tbat the combining proportion of a 

 compound is the sum of its constituents, as hydrogen 1 + oxygen 8 

 = water 9. Davy substituted the word proportion for that of atom, 

 and \Vollaston that of equivalent, which in now generally used ; but 

 whatever be the term, the meaning is the same, and in proportion as 

 analyses have become more accurate, the laws which Dalton laid dowu 

 have been more remarkably confirmed. 



The third volume of Dal ton's ' New System of Chemical Philosophy ' 

 was not published till 1827, but the greater part of it had been printed 

 nearly ten years before. He treats of the metallic oxides, the sul- 

 phurets, phosphurets, carburets, and of the alloys. In the interval 

 between the printing and publication, many of the facts had been 

 anticipated by others, and some of them carried much fai tlier. The 

 most important part of the volume is the appendix, of about 90 

 pages, in which he discusses with his usual sagacity various important 

 matters connected with heat and vapour. He gives a new table of 

 atomic weights, much more copious than those contained in the two 

 prece'Um; volumes, and iu which he introduces the corrections rendered 

 necessary by the numerous correct analyses which bad been made since 

 the publication of the second volume. 



Dr. Dslton's other works, which are tolerably numerous, are inserted 

 in the ' Manchester Transactions,' 'Nicholson's Journal,' the 'Philo- 

 tophical Transactions,' and the ' Philosophical Magazine,' and consist of 

 experiments and observations on heat, vapour, evaporation, rain, wind, 

 the aurora borealis, dew, and a variety of other physical subjects. 



Dr. Dalton was of middle stature and strongly made. His face is 

 said to have resembled the portraits of Newton. His power of mind 

 was naturally strong ; he was a patient observer, and an independent 

 thinker, with the most perfect self reliance, and with an extraordinary 

 power of tracing the relations of physical phenomena ; his experiments 

 bad rarely an insulated character, but were steps in some process of 

 wide generalisation. By such a process, comparing the results of 

 numerous experiments and numerous facts which had been estab- 

 lished, he elicited order out of seeming confusion, and may truly be 

 said to have become the legislator of chemistry, which before his time 

 was little better than an experimental art an accumulated mass of 

 uncounccted and imperfectly-developed facts. Dalton laid down the 

 laws of the combination of substances, and at once advanced chemistry 

 to the rank of a science. His moral character was worthy of his intel- 

 lectual. He was a man of the strictest truth and honesty ; inde- 

 pendent, grave, reserved, but not austere; frugal, but not parsimonious. 

 Unassuming, the honours which he received were voluntarily bestowed 



WOO. DIV. VOL. It 



upon Mm by those who were best able to estimate the value of his 

 services to science and manufacturing industry ; unostentatious, it 

 was some time before his townsmen iu Manchester wera aware of his 

 merits, but a small circle of friends appreciated him highly, and long 

 before he received his pension offered to provide him with an inde- 

 pendence that he might devote the whole of his time to science, but 

 he declined to accept it, observing "that teaching was a kind of 

 recreation, and that if richer he would probably not spend more time 

 in his investigations than he was accustomed to do." His mode of 

 life was singularly uniform. He was rarely from home except when, 

 he went to some place to lecture ; he attended the meeting of the 

 Society of Friends, of which he was a member, twice every Sunday ; 

 he went daily to his laboratory, of which the apparatus was of the 

 simplest and indeed rudest kind; he played at bowls on the afternoon 

 of every Thursday; and he paid an annual visit to his friends and 

 the mountains in Cumberland and Westmoreland. He was never 

 married. 



Daltou was elected a Fellow of the Royal Society about 1821 ; he 

 was elected a corresponding member of the Institute of France, and a 

 few years later was enrolled a Foreigu Fellow. He was also a member 

 of the Koyal Academies of Science of Berlin and Munich, and of the 

 Natural History Society of Moscow. 



(Thomson, History of Chemistry, vol. ii. ; Pharmaceutical Journal, 

 Oct. 1841; Life and Discoveries of Dalton, in British Quarterly 

 Review, No. 1 ; British Association Reports.) 



DAMASCE'NUS, JOANNES, was born at Damascus towards the 

 end of the 7th or the beginning of the 8th century of our era. His 

 father, Sergius, a wealthy Christian of Syria, was councillor to the 

 kalif, and at his death John succeeded him in the same office. His 

 father had given him for preceptor a monk named Cosinas, whom he 

 had redeemed from slavery. About 728 ho wrote several tracts iu 

 defence of image-worship against the Iconoclasts, who were then 

 favoured by the emperor Leo the Isauriau. A legendary story is told 

 of Leo having forged a treasonable letter from John to himself, which 

 he contrived should come into the hands of the kalif, who sentenced 

 John to have his right hand cut off, when the severed baud was 

 restored to the arm by a miracle. About that time however John 

 withdrew from the kalif's court to the monastery of St. Saba, near 

 Jerusalem, where he passed the remainder of his life iu ascetic practices 

 and study. His numerous philosophical and theological works place 

 him among the most distinguished writers of the Eastern Church iu 

 the 8th century. His principal work is an exposition of the ' orthodox 

 faith,' or Christian doctrines, in four books, which unites the two 

 systems of scholastic and dogmatic theology, the former being by 

 ratiocination, according to the Aristotelian or scholastic method, and 

 the second by the authority of the Scriptures and the fathers. This 

 work attained great reputation in the Greek Church, and the author 

 was styled Chrysorrhoas, or 'Golden-flowing,' on account of his 

 eloquence. He promoted the study of Aristotle, and wrote various 

 popular tracts, in which he collected and illustrated that philosopher's 

 principles. He wrote also letters and treatises agaiust heretics, 

 especially against the Manichosans and Nestorians. His principal 

 works have been published by Lequien, ' Opera J. Damasceui,' Paris 

 and Venice, 1748, 2 vols. folio. 



DAMASCE'NUS, NICOLA'US, a philosopher and historian of the 

 age of Augustus, and the friend of Herod the Great, tttrarch of Judiea, 

 is mentioned by Josephus, Athenaeus, Eusebius, and others. He wrote 

 various works in Greek, and among them one on universal history iu 

 141 books, of which we have some fragments, 'N. Damasceni Histo- 

 riarum Excerpta et Fragmeuta qusc supersunt,' 8vo, Leipzig, 1804 ; 

 and again in Paris, 1805, edited by D. Coray. He also wrote his 

 autobiography, of which a considerable portion has been preserved by 

 Suidas and Josephus; a life of Augustus; a life of Herod; some 

 philosophical and some poetical works, none of which have come down 

 to us. The best edition of the remains of N. Dauiasceuus is that of 

 J. C. Orelli, Leipzig, 1S04, with a supplement published in 1811. 



DA'MASUS I., the son of a presbyter, was elected Bishop of Rome 

 after the death of Liberius, A.D. 366. A party amout; the clergy elected 

 the deacon Ursinus in opposition to Damasus, and the people, who had 

 then a share in the elections, being equally divided, the two parties 

 fought iu the streets and in the churches for several days. Ammianus 

 Marcellinus (xxvii. 3), who gives an account of these disorders, states 

 that 137 bodies of the slain were found in one day in the basilica of 

 Sicininus alone. The same author draws a sad picture of the corruptiou 

 of the clergy of Rome in that age, of their cupidity and luxury, which 

 he contrasts with the modest bearing of some of the provincial clergy. 

 In the Theodosian Code (b. xx.) there is an imperial constitution, which 

 was issued about that time for the better discipline of the clergy, in 

 which they are forbidden receiving legacies from widows and minors, 

 frequenting the houses of matrons, cohabiting with women under the 

 pretence of religion, &c. Damasus beiug acknowledged by the bishops 

 of Italy, was confirmed by the Emperor Valentinian, who sent Ursiuus 

 into exile. The party of Ursinus however kept up disturbances in 

 Italy for several years. Ursinus himself returned to Italy. A Jew 

 having brought a charge of adultery against Damasus, the affair was 

 tried by a council of bishops at Home in 378, and Damusus was acquitted. 

 The Euiperor Uratian being appealed to, sent the Jew into exile, as 

 well as Ursinus and several of his party. 



2 K 



