rm.oiMTK 



CHLOROPHYLL 



203 



tin- latter t\\o sliiiuld never be resorted to except 

 under medical supervision. 



Chlorine forms with other BubfitanceH a very 

 large number of chemical compounds. Mixed with 

 hydrogen i" epial volumes, and exposed to sunlight 

 or llamc, union takes place with explosive energy, 

 and hydrochloric, acid, HCI, is produced. Tiiis 

 acid forms an e\ten-i\ e da of salt* called chlorides 

 llvi>i:urin.ui:ic AciD), Imt many of these 

 may In- produced by the direct combination of 

 chlorine with the metals, as in the experiments 

 described above. Chlorine replaces other elements 

 or groups of atom- in organic com]K)iinds, forming 

 chloro derivatives. In comliination with carbon and 

 Indrogen it forms many substances, among which 

 Chloroform (<|.v.) is perhapa chief. Chlorine forms 

 with oxvgen a series of oxygen acids viz. Hypo- 

 chlorous. HC1O; Chlorous, HCIO.,; Chloric, HCK) 3 ; 

 And Perchloric Acid, HCIO., ; th'e more important 

 <>f which are referred to under separate heads. 



Chlorite (Gr. chloros, 'green'), or RIPIDOLITE, 

 an abundant mineral, consisting of silica, alumina, 

 magnesia, and protoxide of iron, in somewhat 

 variable proportions. It is of a green colour, and 

 occurs now and again crystallised in minute hexa- 

 gonal plates, or in aggregates of small leaflets, 

 either singly or disposed in radial groups, which are 

 scattered over the joint-surfaces of certain rocks, 

 or may occur in a thin incrustation upon other 

 minerals. It is rather soft, and is easily broken 

 or scratched with a knife. Before the blowpipe it 

 is with difficulty fused on thin edges. It is readily 

 distinguished from talc by yielding water in a closed 

 tube. There are several other minerals included 

 with ripidolite under the 'chlorite group' which 

 are with difficulty distinguished from ripiaolite and 

 from each other. Chlorite enters largely into the 

 formation of certain schistose rocks (e.g. Chlorite- 

 schist, q.v. ), and is common as a decomposition- 

 product after such minerals as mica, augite, horn- 

 blende, and garnet. 



Clllorite-SChist, a green schistose rock, in 

 which chlorite is abundant in foliated plates, 

 usually blended with minute grains of quartz, and 

 often with felspar, mica, ta-lc, or magnetite. 



Chloritlc Marl, a thin bed of white or pale- 

 yellow marl, sometimes indurated, containing dark- 

 .green glauconitic grains, phosphatic nodules, and 

 iron pyrites. It belongs to the Cretaceous system, 

 coming between the Upper Greensand and Chalk 

 Marl. It is characterised by the abundance of 

 tfi-ri/i/tifi-x fequalis, a species of ammonites. It is 

 confined to the southern districts of England 

 occupied by the Cretaceous rocks. 



Clllorodyne is a patent medicine of con- 

 siderable popularity, invented by Dr James Collis 

 Hrowne (1819-84), but largely imitated by various 

 chemists. It contains opium, chloroform, prussic 

 acid, and probably Indian hemp, and is flavoured 

 with sugar and peppermint. As it is apt to 

 -pa rale into two liquids on standing, it should 

 never be taken unless it has previously been well 

 shaken ; and as, in taking a dose of chlorodyne, the 

 patient swallows an unknown quantity of three 

 or four of the deadliest poisons with which we are 

 acquainted, it is always advisable to begin with 

 small doses. It is unquestionably a compound 

 which sometimes succeeds in allaying pain and 

 inducing sleep when opiates have failed ; but 

 whether a physician is justified in recommending 

 a remedy with the composition of which he is un- 

 acquainted is a doubtful question. To meet this 

 difficulty the Medical Council, in the 1885 edition 

 of the British Pharmacopoeia, have introduced the 

 tincture of chloroform and morphia, which practi- 

 cally represents chlorodyne. Five to fifteen drops 

 is the average dose. 



Chloroform* CHC1,, wa* discovered an a 

 chemical curiosity alout the same time (1831) by 

 Guthrie in America, Liehig in Germany, and 

 Soubeiran in France. S<Mn, however, it* pro- 

 perties as a .stimulant when taken internally 

 attracted attention, and when in 1H47 it WOH 

 brought into prominent notice as an aiWMthetic by 

 Sir James Simpson, it wan at once recognised an 

 one of the most valuable contributions of chemical 

 science to suffering humanity. See ANESTHESIA. 



Chloroform i.s com|>osed of 12 parts of carbon, 

 1 part of hydrogen, and KMi.j, parts of chlorine. It 

 may be produced in several ways, but in thix 

 country at least the process bv which it is obtained 

 from bleaching powder is the only one adopted 

 on the large scale. The materials employed are 

 bleaching powder, alcohol, and water. The bleach- 

 ing powder and water are mixed together to form, 

 a thin cream, the alcohol added, and the whole 

 placed in a capacious still, connected with suitable 

 condensing apparatus. On the application of heat 

 the contents rapidly froth up, and even though 

 the external application of heat be stopped, the 

 chemical action is so violent that the chloroform 

 distils over rapidly along with water and any 

 excess of alcohol. As so obtained it is very impure, 

 and requires to be carefully treated with sulphuric 

 acid, and then redistilled before it is fit for 

 ana-sthetic purposes. Pure chloroform is a limpid, 

 mobile, colourless, volatile liquid, with a character- 

 istic odour, and a powerful sweetish taste. When 

 diluted with alcohol it enters into the composition 

 of artificial fruit-essences, to which it gives a 

 flavour akin to that of ripe apples. It is a very 

 heavy liquid, its specific gravity being about 1 "500 

 (water = TOGO), and as it does not readily mix 

 with or dissolve in water, it falls to the bottom 

 when poured into a vessel of that liquid, forming 

 a distinct layer. Chloroform is readily miscible 

 with alcohol and ether, and it dissolves camphor, 

 amber, gutta-percha, wax, black and red sealing- 

 wax, iodine, and bromine, as well as strychnine 

 and other alkaloids. It dissolves a small propor- 

 tion of water, being also slightly soluble in that 

 liquid. Chloroform is not combustible in the 

 ordinary sense of the term, but when its vapour is 

 brought in contact with flame it burns, imparting 

 a green tint to it, and irritating fumes are pro- 

 duced. Pure chloroform is not met with in 

 commerce owing to the readiness with which it 

 decomposes when exposed to light. In order to 

 prevent this a small proportion of alcohol is added, 

 the specific gravity being thus reduced from 1 '500 

 to 1'497. When evaporated on the hand no 

 disagreeable odour should be noticeable, and when 

 shaken with sulphuric acid only a very slight 

 discoloration of the acid (due to the small pro- 

 portion of alcohol) should result. Besides its 

 anaesthetic properties, which are elsewhere dis- 

 cussed (see ANESTHESIA), chloroform is used in 

 medicine both externally and internally. When 

 a p] i lied to the skin or any of the mucous mem- 

 branes it acts as a powerful irritant, producing a 

 burning sensation, and on this account it i- of 

 value as an application in rheumatism, lumbago, 

 and neuralgia. As an application to a decayed 

 tooth ite action is twofold, as a stimulant and 

 counter-irritant locally, and also to a partial extent 

 as an amcsthetic. Taken internally, diluted with 

 alcohol, it is a powerful stimulant, and readily 

 produce- a species of intoxication. It is by some 

 Habitually taken as a narcotic luxury. As chloric 

 ether, a product distil led from bleaching powder, 

 and containing chloroform, it enters into the com- 

 position of cough mixtures, pick-me-ups, &c. 



Chlorophyll* as its name implies, is leaf -green, 

 the ordinary colouring matter of vegetation. Micro- 

 scopic examination of plant tissues shows it some- 



