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 history and the exploration of the West had few equals—in the latter none. He acted always with uncalculating boldness, and defended his acts with extraordinary courage and persistence. Benton wrote a Thirty Years’ View of the American Government (2 vols., 1854–1856), characteristic of the author’s personality; it is of great value for the history of his time. He also compiled an Abridgment of the Debates of Congress, 1789–1850 (16 vols., 1857–1861), likewise of great usefulness; and published a bitter review of the Dred Scott decision full of extremely valuable historical details—Historical and Legal Examination of the Dred Scott Case (1857). All were written in the last eight years of his life and mostly in the last three.

 BENTON HARBOR, a city of Berrien county, Michigan, U.S.A., on the Saint Joseph river, about 1 m. from Lake Michigan (with which it is connected by a ship canal), near the S.W. corner of the state, and 1 m. N.E. of St Joseph. Pop. (1890) 3692; (1900) 6562, of whom 795 were foreign-born; (1904) 6702; (1910) 9185. It is served by the Père Marquette, the Michigan Central, and the Cleveland, Cincinnati, Chicago & St Louis railways, by electric railways to St Joseph and Niles, Mich., and South Bend, Indiana, and for a part of the year by steamboat lines to Chicago and Milwaukee. One mile south-east of the city are a sanitarium and the Eastman mineral springs; within the city also there are springs and bath-houses. Near the city is a communistic religious community, the Israelite House of David, founded in 1903, the members believe that they are a part of the 144,000 elect (Revelation, vii, xiv) ultimately to be redeemed. Benton Harbor has a large trade in fruit (peaches, grapes, pears, cherries, strawberries, raspberries and apples) and other market garden produce raised in the vicinity. The city’s manufactures include fruit baskets, preserved fruits, cider, vinegar, pickles, furniture, lumber and stationers’ supplies, particularly material for the “loose-leaf ledger” system of accounting. Benton Harbor, which was known as Bronson Harbor until 1865, was incorporated as a village in 1869, was chartered as a city in 1891, and in 1903 received a new charter.

 BENUE, a river of West Africa, the largest and most important affluent of the (q.v.), which it joins after a course of over 800 m. in a general east to west direction from its source in the mountains of Adamawa. Through the Tuburi marshes there is a water connexion between the Benue (Niger) and Shari (Lake Chad) systems.

 BEN VENUE, a mountain in south-west Perthshire, Scotland, 10 m. W. of Callander. Its principal peaks are 2393 and 2386 ft. high, and, owing to its position near the south-eastern shore of Loch Katrine, its imposing contour is one of the most familiar features in the scenery of the Trossachs, the mountain itself figuring prominently in The Lady of the Lake. On its northern base, close to the lake, Sir Walter Scott placed the Coir-nan-Uriskin, or “Goblin’s Cave.” Immediately to the south of the cave is the dell called Beal(ach)-nam-Bo, or “Cattle Pass,” through which were driven to the refuge of the Trossachs the herds lifted by the Highland marauders in their excursions to the lands south of Loch Lomond. The pass, though comparatively unvisited, offers the grandest scenery in the district.

 BENZALDEHYDE (oil of bitter almonds), C6H5CHO, the simplest representative of the aromatic aldehydes. It was first isolated in 1803 and was the subject of an important investigation by J. v. Liebigin 1837 (Annalen, 1837, 22, p. 1). It occurs naturally in the form of the glucoside amygdalin (C20H27NO11), which is present in bitter almonds, cherries, peaches and the leaves of the cherry laurel; and is obtained from this substance by hydrolysis with dilute acids:

C20H27NO11 + 2H2O＝HCN + 2C6H12O6 + C6H5CHO.

It occurs free in bitter almonds, being formed by an enzyme decomposition of (q.v.). It may also be prepared by oxidizing benzyl alcohol with concentrated nitric acid; by distilling a mixture of calcium benzoate and calcium formate; by the condensation of chlor-oxalic ester with benzene in the presence of aluminium chloride, the ester of the ketonic acid formed being then hydrolysed and the resulting acid distilled:

C6H6 + Cl·CO·COOC2H5＝C6H5CO·COOC2H5 + HCl, C6H5CO·COOH＝C6H5CHO + CO2;

by the action of anhydrous hydrocyanic acid and hydrochloric acid on benzene, an aldime being formed as an intermediate product:

C6H6 + HCN + HCl＝C6H5CH : NH·HCl, C6H5CH : NH·HCl + H2O＝NH4Cl + C6H5CHO;

and by the action of chromium oxychloride on toluene dissolved in carbon bisulphide (A. Etard, Berichte, 1884, 17, pp. 1462, 1700).

Technically it is prepared from toluene, by converting it into benzyl chloride, which is then heated with lead nitrate:

C6H5CH2Cl + Pb(NO3)2＝2NO2 + PbCl·OH + C6H5CHO,

or, by conversion into benzal chloride, which is heated with milk of lime under pressure.

C6H5CHCl2 + CaO＝CaCL2 + C6H5CHO.

E. Jacobsen has also obtained benzaldehyde by heating benzal chloride with glacial acetic acid:

C6H5CHCl2 + CH3COOH＝CH3COCl + HCl + C6H5CHO.

Benzaldehyde is a colourless liquid smelling of bitter almonds. Its specific gravity is 1·0636 (° C.), and it boils at 179·1° C. (751·3 mm). It is only slightly soluble in water, but is readily volatile in steam. It possesses all the characteristic properties of an aldehyde; being readily oxidized to benzoic acid; reducing solutions of silver salts; forming addition products with hydrogen, hydrocyanic acid and sodium bisulphite; and giving an oxime and a hydrazone. On the other hand, it differs from the aliphatic aldehydes in many respects; it does not form an addition product with ammonia but condenses to hydrobenzamide (C6H5CH)3N2; on shaking with alcoholic potash it undergoes simultaneous oxidation and reduction, giving benzoic acid and benzyl alcohol (S. Cannizzaro); and on warming with alcoholic potassium cyanide it condenses to (q.v.).

The oxidation of benzaldehyde to benzoic acid when exposed to air is not one of ordinary oxidation, for it has been observed in the case of many compounds that during such oxidation, as much oxygen is rendered “active” as is used up by the substance undergoing oxidation; thus if benzaldehyde is left for some time in contact with air, water and indigosulphonic acid, just as much oxygen is used up in oxidizing the indigo compound as in oxidizing the aldehyde. A. v. Baeyer and V. Villiger (Berichte, 1900, 33, pp. 858, 2480) have shown that benzoyl hydrogen peroxide C6H5·CO·O·OH is formed as an intermediate product and that this oxidizes the indigo compound, being itself reduced to benzoic acid; they have also shown that this peroxide is soluble in benzaldehyde with production of benzoic acid, and it must be assumed that the oxidation of benzaldehyde proceeds as shown in the equations:

C6H5CHO + O2＝C6H5·CO·O·OH, C6H5CO·O·OH + C6H5CHO＝2C6H5COOH.

The oxime of benzaldehyde (C6H5CH : N·OH), formed by the addition of hydroxylamine to the aldehyde, exhibits a characteristic behaviour when hydrochloric acid gas is passed into its ethereal solution, a second modification being produced. The former (known as the or benz-anti-aldoxime) melts at 34–35° C.; the latter ( or benz-syn-aldoxime) melts at 130° C. and is slowly transformed into the  form. The difference between the two forms has been explained by A. Hantzsch and A. Werner (Berichte, 1890, 23, p. 11) by the assumption of the different spatial arrangement of the atoms (see ). On account of the readiness with which it condenses with various compounds, benzaldehyde is an important synthetic reagent. With aniline it forms benzylidine aniline C6H5CH : N·C6H5, and with acetone, benzal acetone C6H5CH : CH·CO·CH3. Heated with anhydrous sodium acetate and acetic anhydride it gives (q.v.); with ethyl bromide and sodium it forms triphenyl-carbinol