809 



CHEMISTRY. 



CHEQUE. 



810 



use of the blowpipe ; and he ascertained that bone is a compound of 

 phosphoric acid and lime. He proved the metallic nature of manga- 

 nese, and stated the properties of the metal. 



The Rev. William Gregor was born in 1762, and died in 1817. In 

 the year 1791 he discovered a peculiar substance in a black sand, found 

 in the parish of Menaccan in Cornwall. This substance was afterwards 

 detected by Klaproth, and by him proved to be a metallic oxide, to 

 the metal contained in which he gave the name of titanium. In 1805 

 Mr. Gregor described a hydrate of alumina found in Cornwall ; he 

 analysed the uranite, and also the arseniate of lead. 



Dr. William Hyde Wollaston was born in 1776, and died in 1828. 

 [WOLLASTON, in BIOQ. Div.] His knowledge was not confined to 

 chemistry : he made acoustics and more particularly optics also his 

 study. His first chemical paper on urinary calculi contained much 

 new information on this subject : he showed that the mulberry calculus 

 ia oxalate of lime mixed with animal matter ; he pointed out a new 

 calculus, which he named cystic oxide, the nature of the triple phos- 

 phate, and of the chalk stones formed on the joints of gouty persons. 

 He discovered two new metals in the grains of native platinum, namely, 

 palladium and rhodium ; he showed that oxalic acid and potash com- 

 bine iii three different proportions, forming the oxalate, binoxalate, 

 and quadroxalate of that alkali. He pointed out the nature of some 

 small copper-coloured crystals found in the slag of an iron furnace, 

 proving by a series of experiments, in a paper which is a perfect model 

 of conciseness and accuracy, that they were metallic titanium. He 

 perfected the method of rendering platinum available for the purposes 

 of chemistry and the chemical arts, and his ' Scale of Chemical Equiva- 

 lents,' more effectually elucidated and extended the doctrine of definite 

 proportions than all that had been previously done both by theory and 

 practice. He first showed that the evolution of voltaic electricity is 

 dependent upon chemical action, a fact which has been since amply 

 and ably illustrated by Faraday. His ' Reflective Goniometer ' has 

 given to crystallography all the minute accuracy which it previously 

 stood in need of; for it showed that three substances, namely, the 

 carbonate of iron, lime, and magnesia, which were previously supposed 

 to crystallise in rhomboids measuring the same angles, had all different 

 angles. His paper on the finite extent of the atmosphere is replete 

 with curious and acute observations; and he invented some optical 

 instruments, which we need not here particularly describe. 



Humphry Davy was born at Penzance, in Cornwall, in 1778, and 

 died in 1829. [DAVY, in BIOG. Div.] To the researches and dis- 

 coveries of this justly celebrated chemist it will be impossible to do 

 justice in the space to which we are confined. His first contributions 

 to chemical science were published in 1 799, in a work edited by Dr. 

 Beddoes, entitled ' Contributions to Physical and Medical Knowledge.' 

 The first paper is ' An Essay on Heat, Light, and the Combinations of 

 Light,' and the second ' On the Generation of Phos-oxygen (oxygen 

 gas), and on the Causes of the Colours of Organic Beings;' these, 

 although stamped with the mark of genius, are more remarkable for 

 the speculative than experimental nature of their contents. In 1800 

 he published a work, entitled ' Researches, Chemical and Philosophical ; 

 chiefly concerning Nitrous Oxide, or Dephlogisticated Nitrous Air, and 

 its Respiration.' In this, which is a work of high merit, he details the 

 effects produced by the respiration of nitrous oxide both on himself 

 and others. The very high reputation which he had acquired by this 

 work was greatly increased by his paper in the ' Philosophical Trans- 

 actions ' for 1807, entitled, ' On some Chemical Agencies of Electricity.' 

 In this paper he showed that the acid and alkali which had before 

 been observed to be developed by galvanic agency were derived from 

 the decomposition of some previously existing salt, and were not 

 formed by the electric action. He arrived at the conclusion, from the 

 numerous experiments described in this paper, that all bodies pos- 

 sessing chemical affinity for each other are in different electrical states, 

 and that the degree of the affinity is proportional to their intensity. 

 By the agency of voltaic electricity he decomposed the alkalies, potash 

 and soda, and obtained from them metallic bodies, to which he gave 

 the names potassium and sodium; he succeeded also in separating 

 metals from lime, baryta, strontia, and lithia; he was not however 

 equally successful in decomposing those earths which have no alkaline 

 properties, as alumina, glucina, yttria, and zirconia, though these have 

 lince yielded to other modes of decomposition. In 1807 he also 

 discovered boron, the metalloid of boracic acid. 



In 1811 Davy read a paper to the Royal Society, in which he showed 

 that what was called oxymuriatic acid by Berthollet, instead of being, 

 as he supposed, a compound of oxygen and muriatic acid, was, in fact, 

 an undecomposed substance, and therefore must be regarded as an 

 element, and he gave to it the name of chlorine from its green colour. 

 These views, though at first strongly opposed by Berthollet and Dr. 

 Murray, are now universally adopted. In the following years he con- 

 tributed various important papers to the Royal Society, and among 

 them the following : On a compound of chlorine and oxygen ; on 

 chloride of nitrogen ; on iodine ; the combustion of the diamond ; on 

 the salts called hyperoxymuriatic ; on fire-damp, and the means of 

 preventing accidents in mines ; and his invention of the safety lamp ; 

 a similar, but less successful, form of safety lamp, depending how- 

 ever upon entirely different principles, having been just previously 

 invented by Stephenson. In succeeding years he published various 

 papers on electricity, electro-magnetism, and on a method of preventing 



the corrosion of copper sheathing ; this plan, though based on sound 

 philosophy, failed in its object, from the very unexpected cause of the 

 sheathing being rendered foul. His last paper was in 1819, on the 

 tlectricity of the torpedo. 



In 1812 Davy published the first part of the ' Elements of Chemical 

 Philosophy,' a work which was never completed. It embodied the 

 results of his discoveries, and an account of certain views of the author 

 up to 'the time at which it appeared. This work bears occasional 

 marks of haste, yet it contains evidence of its emanating from a genius 

 of the highest order. 



In concluding this brief sketch, it is hardly necessary to remark that 

 the discoveries alluded to in it placed their author at the head of the 

 science which he illustrated, not merely in England but in Europe ; 

 and his fame will rest on the durable base of experimental discovery 

 and great talent for generalisation. 



In giving a history of chemistry, it is impossible not to notice the 

 doctrine of definite proportions, or the atomic theory ; under which 

 head we have entered pretty fully into the history of its discovery, and 

 mentioned the contributors to its development, whether deceased or 

 living. In that article the discoveries and labours of Wenzel, Dr. 

 Higgins, Mr. Higgins, Richter, Proust, Dalton, Wollaston, Berzelius, 

 Gay-Lussac, and Prout, are detailed so amply as to require no further 

 notice here. 



There are still some other subjects which it is necessary to mention, 

 though we cannot allude to all the discoveries which their respective 

 authors have made. In 1803, Sertuerner, a German apothecary, dis- 

 covered in opium the first of a new class of alkaline bodies, or the 

 vegetable alkaloids, but this discovery excited little notice, till the 

 author published a second paper in 1816 ; this alkaloid is morphine. 

 Since this time numerous others have been found ; they are most of 

 them very active substances, and frequently poisonous. Thus the 

 different kinds of cinchona have yielded amongst others two alka- 

 loids, quinine and cinchonine, to which their virtues are owing : these 

 were discovered by Pelletier and Caventou, iu 1820. It has been found 

 that many of the most active vegetable substances, such as hemlock, 

 nux vomica, tobacco, and many others, contain alkaloids. 



In 1812, iodine, a peculiar elementary substance, was discovered by 

 M. Courtais, of Paris. The nature of this body was made the subject 

 of numerous experiments both by Davy and Gay-Lussac. Its discovery 

 served the purpose of illustrating and confirming the new views of 

 Davy as to the simple nature of chlorine. 



In 1818 Berzelius discovered a peculiar inflammable elementary 

 body, to which he gave the name of selenium. In 1824 he obtained 

 the elementary bases of silica and zirconia ; and in 1829 he found a 

 new metal, to which he gave the name of thorium. In 1818 Stromeyer 

 discovered cadmium, a new metal ; and in the same year lithium was 

 discovered by Arfwedson ; Bussy obtained magnesium from its oxide 

 in 1829, and in 1830 Sefstrom discovered the metal vanadium. 



Up to this time the study of organic chemistry had been little 

 cultivated, the difficulties surrounding the analysis and investigation 

 of organic compounds having greatly contributed to retard the pro- 

 gress of knowledge in this direction. These difficulties were to a great 

 extent removed by the early labours of Liebig, who, in conjunction 

 with Berzelius, drew universal attention to this branch of the science, 

 rendering it, even to the present day, the most attractive field of re- 

 search to the chemical investigator. To these chemists is due the 

 origination and development of the radical theory of organic com- 

 pounds, a theory, the value of which, in stimulating and directing 

 investigation, and in facilitating the study of organic compounds, can 

 scarcely be overrated. It served as a thread in the daily widening 

 labyrinth of organic bodies, guiding the investigator to new discoveries 

 and generalisations. Still more recently this branch of the science has 

 received a not less important impulse from the labours of Laurent and 

 Gerhardt ; the originality of thought and unwearied industry of these 

 chemists render their early death a grievous loss to science. 



We cannot better conclude this slight sketch of the progress of 

 chemistry than by adopting the words of Sir H. Davy on a similar 

 occasion : " To dwell more minutely upon the particular merits of 

 the chemical philosophers of the present age will be a grateful labour 

 for some future historian of chemistry ; but for a contemporary writer 

 it would be indelicate to assume the right of arbitrator, even where 

 praise only can be bestowed." 



CHEMISTRY, as applied to Agriculture. [RURAL ECONOMY.] 

 CHENOCHOLIC ACID. The soda salt of Ibis acid is said to be 

 contained in the bile of the goose, but as its composition is not known, 

 its existence as a separate acid is doubtful. 



CHEQUE, a written order on a banker by a person who has 

 money in the bank, directing him to pay a certain sum of money to 

 the bearer, or to A. B. or bearer, or to A. B. or order, which is signed 

 by the drawer. In order to exempt this instrument, so nearly 

 resembling a bill of exchange, from the stamp duty imposed in respect 

 of bills, it was required by the Stamp Act of Geo. III. (55 Geo. III. 

 c. 184), still in force, (1) that it be for the payment of money to the 

 bearer on demand, (2) and be drawn upon a banker residing or 

 carrying on business within fifteen miles of the place of issue, (3) that 

 the actual place of issue be stated in the cheque, (4) that it bear date 

 on or before the day of issue, (5) and that it do not direct payment 

 to be made in bills or promissory notes. The Act, 21 Viet. c. 18 



