

CALflfM. 



600 



to your Mini), meaning, when jott an no more I will <! all 

 IMibl* hoooor to TOUT maun." Cairo* or remains of cairu*, ore 

 found throughout the Britfch islands; in France, (specially in 

 Brittany) ; also, but rarely as oompwci with earthen tumuli, in Qer- 

 many, Sweden and Denmark, and other part* of Europe. 



Jamieso^inhis'Etyuiological Dictionary. 'say.." In Angus, where any 

 person ha. been murdered, a cairn U erected on the spot." [TUMULUS.] 

 980M V water-tight vessel oMd in hydrauUo engineering. for 

 the purpose either of clu*ing the entrance to a dock, or any rimilar 

 wort ; or of receiving UK foundation, of a building, which are sub- 

 sequently cunk upuo a bed formed to receive them, and the caisson 

 JUelf. In ' Vitruvius de Architectura,' lib. 5, cap. 12, there w a 

 description of the mode of employing a species of caisson, or enclosure, 

 to receive the commencement of works to be erected in deep water, 

 which differ* little from that still used by the Italian engineers ; but 

 the first Instance on record of the use of caissons on a Urge scale, was 

 in the cmse of the New Westminster Bridge, executed under the orders 

 of Labelrye a Swiss engineer, about the year 1 740. The next instances 

 of their application were in the case of the bridge of Saumur, about 1757, 

 and in many other important works erected by De Cessart. In 

 England, Smeaton and Semple frequently employed this method of 

 executing the foundations of buildings to be erected in deep water ; and 

 the former even adopted it in the case of the Ramsgate harbour. It 

 has, however, been found, practically, that if the substratum upon 

 which a caisson is sunk should be susceptible of being undermined, 

 there is great danger of the superstructure being also carried away ; 

 and, at the present day, the use of caissons for foundation purposes is 

 almost exclusively confined to such positions as offer naturally a rocky 

 substratum. Caisson gates are, however, still extensively used in 

 dockworks, especially when the gates are not obliged to be frequently 

 opened ; and it is for this reason that they are more commonly to be 

 met with in military than in commercial ports. 



The caissons formerly used for foundation purposes were in f.u-t 

 timber frames large enough to receive the whole of the intended base. 

 Then frames were brought over the position they were meant sub- 

 sequently to occupy, and which had been prepared to receive them by 

 dredging, or by the use of the diving-bell ; and when the masonry of 

 the proposed structure had been raised to a sufficient height, the frame 

 was pierced and sunk. Evidently in such cases the success of the 

 operation depended upon the equal resistance of the ground to be 

 covered, and upon its subsequent powers of resistance to the under- 

 mining action of the currents ; conditions which can hardly ever be 

 secured in practice. Moreover, it is almost impossible to secure the 

 perfectly vertical position of the mass to be sunk, and thus the defects 

 of the substrata become exaggerated. When caissons are used upon 

 rocky strata, it is customary to make them open at both ends ; and, at 

 the present day, to fill them in entirely with concrete, as was done at 

 Rochester and Saltash. 



A species of caisson was suggested by Coulomb, in a very curious 

 treatise ' Sur les rnoyens d'executer sous 1'c.iu toutes sortea de travaux 

 hydrauliques,' 8vo, Paris, 1779, which has been subsequently adopted 

 and improved, in England and in France, in a manner to be noticed 

 hereafter under FOUNDATIONS. 



CAJUPUT OIL. This oil It obtained from the leaves of the 

 itelaleuca minor, a tree of the natural order Myrtacese. The wood of 

 the tree is white, hence the name cajuput ( kayu-puti, u-hite irW). It 

 grows in the Molucca isles. The leaves are packed in sacks, allowed 

 to ferment for a short time, and then distilled with water, when the 

 oil is carried over with the steam and floats on the condensed liquid. 



Cajuput oil as imported is of a green colour, limpid and transparent. 

 It has an aromatic odour, and a taste somewhat resembling camphor. 

 Its specific gravity in usually 0-92. Boiling point 847 Fahr. It may 

 be purified by redistillation. Its chemical composition is, according to 

 Blanchett, C JO H,,O l . Cajuput oil is soluble in alcohol, without acid 

 reaction, and when pure is quite colourless. It has been asserted that the 

 colour of the oil is owing to the presence of copper derived from the 

 vessels hi which it has been stored : this is not the case ; the colour is 

 due to chlorophylle, or a matter closely resembling chlorophylle. 



Cajuput oil u a medicinal agent. Internally it acts as a diffusible 

 stimulant and antispasmodic, externally as a sudorific. 



X.IM-, CARBOSATE OF.] 

 CALAMUS. [DHAUOS'S BLOOD.] 



CALCINATION. This chemical term is derived from eals, the 

 Latin fur quicklime, which, as well known, is prepared by the action 

 of beat upon limestone : the old chemists, therefore, employed the 

 word calcination to express any supposed analogous change; for 

 example, when cerUin meUls, as tin and rinc, are exposed to heat and 

 air, they were atid to be calcined, and the product was called a cals, as 

 of tin or tine. 



It will be observed, therefore, that different 



operation 



included 



in this term : Ant, the expulsion of carbonic acid, as when lime is 

 prepared; secondly, the acuuisition of oxygen when the metals an 

 heated. and the remits of the action of heat and air upon them were 

 termed CO/TO : thus calx of tin is now called oxide of tin. 



The term calcination U jret employed to express the separation of 

 the volatile from the more Axed parts of a body : thus bones which 

 are heated till they become black are termed burnt lionet ; but when, 

 by the further operation of heat, they become white, they are called 



ealeuud boe> ; so also we say calcined flints, calcined clay, sulphate of 

 hue, ftc. But what were formerly termed metallic calces or calcined 

 metals are now described as metallic oxides. 



CAL'CIUM (Ca), a peculiar metal, of which lime is the well-known 

 oxide. It was first obtained by Davy, in 1808, by the action of voltnic 

 electricity ; he made chalk or carbonate of lime into a paste with water, 

 and placing it on a plate of platinum, a cavity was made in the paste 

 to receive a globule of mercury. The mercury was rendered negative 

 and the platinum positive by means of a battery of about 100 double 

 plates. In this way the lime being decomposed, its metal formed an 

 imalgaui with the mercury. This amalgam was distilled in glass tubes 

 illed with the vapour of naphtha. In an experiment in which th" 

 greater part of the mercury was expelled, the tube broke whilst warm, 

 lir entered, the met d, which had the colour and lustre of silver, 

 instantly took fire, and burnt, with an intense white light, into lime. 



Calcium has been recently investigated by Dr. Matthiesen, who 

 obtained a considerable quantity of it by the electrolytic decomj 

 of a fused mixture of the chlorides of calcium and strontium, in the 

 proportion of two equivalents of the former to one of the latter. For 

 details of the operation, see ' Quarterly Journal of the Chemical 

 Society,' vol. viii. p. 28. 



The specific gravity of calcium is 1'5"8. It U of a very light gold 

 colour, is malleable and ductile, and possesses a hardness intermediate 

 between lead and gold. Exposed to the air at ordinary temperatures 

 it soon tarnishes by combining with oxygen, and at a red heat melte, 

 and in a current of air burns with a dazzling white light, at the same 

 time throwing off beautiful scintillations. It also burns brilliantly in 

 an atmosphere of chlorine, bromine, iodine, or sulphur. It rapidly 

 decomposes water, setting free and taking the place of the hydrogen. 

 These properties of calcium have still more recently been confirmed by 

 MM. Lice-Boudart and Jobin, who have obtained it by the action of 

 sodium on iodide of calcium at a red heat iu closed iron vessels. They 

 fix its spec. grav. at 1'55. Compounds of calcium with other elements 

 have been long known and extensively employed ; the first we shall 

 mention is lime, resulting from the union of 



Oxygt* and Calcium: these substances combine to form two com- 

 pounds ; namely, lime, or the protoxide of calcium, and the peroxide of 

 calcium. It has just been mentioned that calcium and oxygen unite 

 with great force of affinity, which of course prevents calcium from 

 occurring in nature uncombined with this element. Lime has been 

 known from the remotest antiquity, and is one of the most abundant 

 and universally diffused substances in nature. It is never found pure, 

 but always combined either with other earths, or more generally with 

 acids ; for example, with carbonic acid in marble, chalk, limestone, and 

 calcareous spar, and in the shells of fish and eggs of birds ; with sul- 

 phuric acid it constitutes sulphate of lime, or gypsum ; with phosphoric 

 acid it forms the earthy part of animal bone ; and with silica and other 

 earths it enters into the composition of many minerals and precious 

 ton) -. 



Lime (CaO) U easily obtained in a pure state : the carbonate or any 

 limestone free from impurity is to be mixed with coal or charcoal and 

 exposed to a strong heat ; in this way the carbonic acid is expelled, and 

 the lime, or oxide of calcium, remains : this is, iu fact, the common 

 process of lime-burning, and the product U frequently called quick- 

 lime. 



Lime is composed of 



1 Equivalent of calcium = 20 

 1 oxygen = 8 



Equivalent = 28 



The properties of lime are : It is white, opaque, inodorous, and its 

 taste is acrid and alkaline; its specific gravity is 3'15. It is in: 

 in the strongest furnaces ; but small quantities have been fused by the 

 oxy-hydrogen blowpipe. By exposure to the air it attracts moisture 

 and carbonic acid, and falls to powder. Lime has great affinity for 

 water ; the compound U solid, and called kydrate of lime. Lime-train- 

 is a solution of hydrate of lime in water. 



Hydrate of /.tine (CaO, HO), or, as it is usually called, ilaleed 1, 

 distinguish it from quick-lime, is readily prepared by sprinkling thin 

 earth with water; it almost immediately heats, cracks, swells, and 

 becomes powdery. During this <>|>cr;itiii part of the water is rendered 

 K. .lid and combines with the lime, while another portion is expelled in 

 vapour, light as well as heat being evolved ; indeed the degree of heat 

 has been found sufficient to set fire to buildings in which lime has been 

 :,. . ill, ntally exposed to water. 



Wln-n quick-lime is exposed to the air it gradually absorbs both water 

 and carbonic acid, falls to powder, and in that state is termed air- 



Lime-water is easily prepared by adding the earth to water, but it is 

 better to employ the hydrate for this purpose ; and it is a curious 

 circumstance, first noticed by Dr. Priestley, that cold water dissolves a 

 larger quantity than hot : thus an imperial pint of boiling water dis- 

 solves only 6] grains of lime, but at near 82 it takes up almost exactly 

 13J grains. When lime-water prepared with cold water is heated to 

 ebullition it deposits crystals of lime ; but it does not part with any at 

 common temperatures. 



Lime-water has a disagreeable taste, and the alkaline property of 



