CITRIC ACID 805 



CINDER IRON. See IRON. 



CINDER TAP. See IRON. 



CINNABAR is the principal and only valuable ore of mercury which is prepared 

 from it by sublimation. 



It is a sulphide (sulphuret) of mercury, composed, when pure, of quicksilver 86'2, 

 .sulphur 13'8, in which case it is a natural vermilion, and identical with the vermilion 

 of commerce ; but it is sometimes rendered impure by an admixture of clay, bitumen, 

 oxide of iron, &c. Cinnabar is of a cochineal-red colour, often inclining to brownish- 

 red, and lead-grey, with an adamantine lustre, approaching to metallic in dark 

 varieties, and to dull in friable ones. It varies from sub-transparent to opaque, has a 

 scarlet streak, and breaks with a sub-conchoidal uneven fracture. H = 2to 2'5, specific 

 gravity = 8'99. In a matrass it entirely sublimes, and with soda yields mercury with 

 the evolution of sulphurous fumes. When crystallised, it belongs to the rhombohedral 

 system. 



Cinnabar occurs in beds in slate-rocks. The chief European beds are at Almaden, 

 near Cordova, in Spain, and at Idria in Carniola, where it usually occurs in a massive 

 form, and is worked on a thick vein belonging to the carboniferous series. It also occurs 

 abundantly in China, Japan, Huanca Vilica in South Peru, and at New Almaden in 

 Santa Clara Co., and in other parts of California, where extensive mines of cinnabar 

 are worked. It is also abundant in Idaho. The chief source of the mercury used 

 in England, is Spain. Our recent imports of native Cinnabar cannot now be ascer- 

 tained, as it is all entered at the Custom House under the head of ' Ores unenumerated.' 



Cinnabar in the arts is used as a pigment, in the state of a fine powder, which is 

 known by the name of vermilion. See MEBCTTRY and VERMILION. 



CINNAMON. (Cannelle, Fr. ; Zimmt, Ger.) The inner bark of the Laurus 

 cinnamomum, used chiefly for flavouring cordials. Cinnamon yields an exquisite 

 essential oil by distillation which has considerable use in medicine and perfumery. It 

 is largely used for incense, but its principal consumption is in Spain, for the fabrica- 

 tion of chocolate, where it is said not less than 50,000,000 Ibs. are used annually, 

 nearly the whole of which is brought from Ceylon. 



Of cinnamon we imported as follows : 



Ibs. Value 



In 1870 2,215,434 252,875 



1871 1,574,946 143,520 



1872 1,082,134 111,496 



CINNAMON STONE. A name given to Essonite, one of the varieties of 

 the lime garnets. Many so-called hyacinths are really nothing more than fine- 

 coloured cinnamon stones. 



CIPOIilNO. An Italian marble, of white colour, with pale green markings. 



CITRIC ACID. (Acide citrique, Fr. ; Citronensaure, Ger.) This acid exists in 

 the juice of fruits, especially the lemon, orange, currant, and quince. It was first 

 procured from lemon-juice in a pure state by Scheele, who adopted the following 

 process : Lemon-juice was put into a large tub, and saturated with dry chalk in fine 

 powder, noting carefully the quantity employed. The citrate of lime which preci- 

 pitates being freed from the supernatant liquor is to be well washed, with repeated 

 affusion and decantation of water. For every ten pounds of chalk employed, nine 

 and a half pounds of sulphuric acid diluted with six times its weight of water are to be 

 poured while warm upon the citrate of lime, and well mixed with it. At the end of 

 twelve hours, or even sooner, the citrate will be decomposed, dilute citric acid will 

 float above, and sulphate of lime will be found at the bottom. The acid being 

 drawn off, the calcareous sulphate must be thrown on a canvas filter, drained, and 

 then washed with water to abstract all the acid. 



The citric acid thus obtained may be evaporated in leaden pans, over a naked fire, 

 till it acquires the specific gravity 1-13 ; after which it must be transferred into 

 another vessel, evaporated by a steam or water bath till it assumes a syrupy aspect, 

 when a pellicle appears first in patches, and then over the whole surface. This point 

 must be watched with great circumspection, for if it be passed, the whole acid runs 

 a risk of being spoiled by carbonisation. The steam or hot water must be in- 

 stantly withdrawn, and the concentrated acid put into a crystallising vessel in a dry, 

 but not very cold apartment. At the end of four days the crystallisation will be 

 complete. The crystals must be drained, re-dissolved in a small portion of water, 

 the solution set aside to settle its impurities, then decanted, re-evaporated, and 

 re-crystallised. A third or fourth crystallisation may be necessary to obtain a colour- 

 less acid. 



If any citrate of lime be left undecomposod by the sulphuric acid, it will dissolve 

 in the citric acid, and obstruct its crystallisation, and hence it will be safer to use the 



