JAMRUD, a fort and cantonment in India, just beyond the border of Peshawar district, North-West Frontier Province, situated at the mouth of the Khyber Pass, 10½ m. W. of Peshawar city, with which it is connected by a branch railway. It was occupied by Hari Singh, Ranjit Singh's commander in 1836; but in April 1837 Dost Mahommed sent a body of Afghans to attack it. The Sikhs gained a doubtful victory, with the loss of their general. During the military operations of 1878-79 Jamrud became a place of considerable importance as the frontier outpost on British territory towards Afghanistan, and it was also the base of operations for a portion of the Tirah campaign in 1897-1898. It is the headquarters of the Khyber Rifles, and the collecting station for the Khyber tolls. Pop. (1901), 1848. JAMS AND JELLIES. In the article FOOD PRESERVATION it is pointed out that concentrated sugar solution inhibits the growth of organisms and has, therefore, a preservative action. The preparation of jams and jellies is based upon that fact. All fresh and succulent fruit contains a large percentage of water, amounting to at least four-fifths of the whole, and a comparatively small proportion of sugar, not exceeding as a rule from 10 to 15%. Such fruit is naturally liable to decomposition unless the greater proportion of the water is removed or the percentage of sugar is greatly increased. The jams and jellies of commerce are fruit preserves containing so much added sugar that the total amount of sugar forms about two-thirds of the weight of the articles. All ordinary edible fruit can be and is made into jam. The fruit is sometimes pulped and stoned, sometimes used whole and unbroken; oranges are sliced or shredded. For the preparation of jellies only certain fruit is suitable, namely such as contains a peculiar material which on boiling becomes dissolved and on cooling solidifies with the formation of a gelatinous mass. This material, often called pectin, occurs mainly in comparatively acid fruit like gooseberries, currants and apples, and is almost absent from strawberries and raspberries. It is chemically a member of the group of carbohydrates, is closely allied with vegetable gums abundantly formed by certain sea-weeds and mosses (agar-agar and Iceland moss), and is probably a mixture of various pentoses. Pentoses are devoid of food-value, but, like animal gelatine, with which they are in no way related, can form vehicles for food material. Some degree of gelatinization is aimed at also in jams; hence to such fruits as have no gelatinizing power an addition of apple or gooseberry juice, or even of Iceland moss or agar-agar, is made. Animal gelatin is very rarely used.