Gelatin, Patent

Various qualities of gelatin are manufactured from glue pieces, or cuttings of the hides of beasts and skins of calves, and from inferior isingla . According to Mr Nelson’s specification, the crude materials, freed from hair, wool, flesh, and fat, after being thoroughly washed and ‘scored,’ are macerated for 10 days in a lye of caustic soda, and are then placed in covered ve els at a temperature varying from 60° to 70° Fahr., until they become tender; they are next washed to free them from alkali, and are then exposed to the vapour of burning sulphur until they acquire a sensibly acid reaction; they are now di olved in water contained in earthen ve els heated to 150° Fahr., and the solution, after being strained, is put into ‘settling ve els,’ and heated to 100° to 120° Fahr., for 8 or 9 hours; at the end of this time the clear liquor is drawn off, and poured on the ‘cooling slabs,’ to the depth of about 1 ⁄ 2 an inch. As soon as the jelly is cold, it is cut into pieces, and washed in water until perfectly free from acid. It is then redi olved in water at about 85°, the solution poured out on slabs as before, and when cold, it is cut up, and, lastly, dried on nets. According to another specification (Rattray’s Patent) glue-pieces are steeped in water until they begin to putrefy, then washed with water, drained, and put from 12 to 24 hours into water strongly soured with sulphurous acid; they are afterwards washed first with cold water, and then in water at 120° Fahr., and are lastly converted into size by digestion for 24 hours in water at 120° Fahr., the resulting solution being filtered through bags of double woollen-cloth. Patent gelatins are often sold cut up in imitation of ‘picked isingla ,’ to which, for the preparation of jellies, soups, and blancmanges, they are not much inferior.