Volume 1
Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors.
- Date:
- 1888-1894
Licence: Public Domain Mark
Credit: Watts' dictionary of chemistry / revised and entirely rewritten by H. Forster Morley and M.M. Pattison Muir ; assisted by eminent contributors. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
703/796 (page 677)
![Ethyl ether A'Et (c. 300°). Oxim C,0H„O3(NOH) : [175°_180°] ; colourless four-sided plates (Piccard, B. 10, 1504 ; 11, 2121; Homolka, B. 19, 1086). CANTHARIDIC ACID C10H,,05 i.e. (CBHlsO.,).CO.CO,H. The alkaline salts are formed by heating cantharidin with aqueous alkalis. When a cold solution of the salts is treated with acids, the free cantharidic acid appears to be formed, but on warming the solution it loses H,0 and cantharidin is pre- cipitated. With hydroxylamine it gives an oxim, from the salts of which acids liberate the oxim of canthavidine.—Ag.,A aq. —Ag.,A 2aq. (NHJ.A/'aq.—KAaq.-CdA''aq.—K,CuA,2aq. Di-melhyl ether AMe2: [91°]; large Hat glistening prisms; sol. alcohol, ether, and hot water, si. sol. cold water (Homolka, B. 19, 1082 ; Dragendorff a. Masing, Z. 1867, 464; Masing, J. 1872,841). CANTHARIDIN C10H12O4. Lactone of can- tharidic acid. [218° cor.]. S. -02 at 15° ; -29 at 100° ; S. (alcohol) 2-1 at 78° ; -13 at 15° ; S. (benzene) 3'38 at 80°; -51 at 15° (Kennard); S. (ether) -11 at 18°; S. (CS.,) -06 at 18°; S. (CHC1:1) 1-2 at 18° (Bluhm). Occurrence.—In Spanish flies (Lytta vesi- catoria) and many other insects (Thierry, A. 15, 315; Ph. 21,44; Robiquet, A. Ch. 76, 302; Gossmann, A. 86, 317 ; Pocklington, Ph. [3] 3, 681; Regnault, A. Ch, [2] 68, 159 ; Warner, Am. J. Ph. 28, 193; Ferrer, 1860, 597 ; Mortreux, J. Ph. [3] 46, 33 ; Fumouze, J. Ph. [4] 6, 161; Bluhm, Z. [2] 1, 675; Dragendorff, Z. [2] 3, 187, 464 ; 4, 308; Rennard, C. C. 1872, 568; Wolff, Ar. Ph. [3] 10, 22 ; Piccard, B. 10, 1504). Preparation.—1. Powdered cantharides are extracted with chloroform or ether, the solvent is evaporated and the residue freed from fat by washing with CS.,.—2. Cantharides are mixed with water and MgO, dried, treated with dilute H.SO, and then shaken with ether. Properties.—Trimetric plates. Blisters the skin. Sublimes readily at 85° (Blyth). Reactions.—1. HI forms cantharic acid.— 2. By distillation with P.,S5 it gives o-xylene (Piccard, B. 12, 580).—3. By heating with alkalis it is converted into salts of cantharidic acid C,0HuO5) from whose hot solutions cantha- ridin is re-precipitated on the addition of acids. Oxim CluH,,0:j(NOH) : [166°]; splendid long glistening prisms; v. e. sol. alcohol and ether, v. sol. hot water, si. sol. cold. By cone. HC1 at 150° it is split up into its constitu- ents. — C^H^O,(NOAg): four-sided prisms.— C^H^.O^NOMe): [134°]; large colourless prisms; v. e. sol. alcohol and ether, v. sol. hot, si. sol. cold, water (Homolka, B. 19,1082). Compound C10H12O3I.,. 'Cantharidin iodide ' is formed as a by-product (5-8 p.c.) in the preparation of cantharic acid by the action of HI (1-96 S.G.) upon cantharidin at 85°. Crys- talline solid. V.sol. benzene and chloroform, si. sol. alcohol, insol. water. On boiling with cone. KOH it is converted into pure cantharene (o-xylene-di-hydride) C6H6(CH3)2 (Piccard, B. 19, 1404). CAOUTCHOUC. India rubber. This sub- stance is obtained from the milky sap of various trees belonging to several natural orders. The sap, which is obtained by making an in- cision in the bark of the tree, is a white creamy liquid with a sp. gr. 1-012. The caoutchouc exists in the sap in the form of minute globules, and is consolidated in various ways, often by heating over a smoky fire which produces the brown colour of the commercial article. Caoutchouc is colourless when pure, it is a bad conductor of heat and a non-conductor of electricity. S.G. about -925. At ordinary tem- peratures it is soft, flexible, and very elastic, but at about 10° it begins to lose its elasticity, and at 0° becomeshard and rigid. When heated j it loses it; elasticity and becomes soft, slowly resuming its original properties when cooled ; if heated to 150°-200° it melts, and after this it remains semi-liquid and sticky on cooling. It burns readily with a smoky flame, leaving little or no ash. Exposure to air in the absence of light pro- duces little effect on caoutchouc, but light and air together cause it to lose its elasticity and become glutinous, due to the absorption of oxygen (Spiller, C. J. 18, 44; Miller, ibid. p. 273). Caoutchouc is insoluble in water, but when immersed in it becomes white and increases in bulk, absorbing about 25 p.c. of its weight of water, which is given up again on exposure to air. Alcohol acts up jn it in a similar way. Dilute acids do not affect it, but it is attacked by strong nitric or sulphuric acid. Chlorine renders it hard and brittle. Alkalis produce little effect. Ether, benzene, mineral oil, sulphide of carbon, chloroform, oil of turpentine, oil of caoutchouc, and many essential and fixed oils, act upon caoutchouc, causing it to swell greatly and become gelatinous and soft. The action of these solvents appears to be to dissolve one constituent part of the caoutchouc, leaving the less soluble part in a disintegrated condition. According to Payen, sulphide of carbon with about 5 p.c. of absolute alcohol is the best solvent. Caoutchouc is composed of carbon and hy- drogen. The proportions vary in different analyses C. 86-1-90-6 p.c; H. 10-12-8 p.c. It appears to consist chiefly of two hydrocarbons, which can be partly separated by the prolonged action of a solvent, but the proportion of these constituents obtained varies according to the solvent employed. The more soluble part is soft and ductile, while the less soluble is tena- cious and elastic. When caoutchouc is subjected to dry dis-- filiation an oil consisting of a mixture of various hydrocarbons is obtained. This is called oil of caoutchouc. Among the constituents of this oil are iso- prene C5H9 (37°-38°) S.G. -682; caoutchene C„,H1C (171°) S.G. -842, and heveene (315°) S.G. -921 (Himly, A. Ch. 27, 41; Gregory, ibid. 16, 61; G. Williams, Pr. 10, 517; Bouchardat, J. Ph. 1837, 454 ; Bl. 24, 108; C. B. 89, 361). When isoprene is acted on by strong hydric chloride a mixture of the mono- and di- hydro- chlorides, together with a solid substance, is obtained. This latter is identical in its proper-](https://iiif.wellcomecollection.org/image/b21995990_0001_0703.jp2/full/800%2C/0/default.jpg)
