For red grape juice the grapes are crushed, but not pressed. The crushed grapes are taken into large heating caldrons, usually made of aluminum, and furnished with a steam jacket. The temperature of the crushed grape is carried to about 175°F. for a period of 15 minutes, the mass being well stirred during this period of heating. The purpose of heating the grape juice is first to pasteurize it, but especially to extract the red coloring matter from the skins. After extracting the color and pasteurization the juice is separated from the pulp, either by gravity or generally afterward by pressure, and conducted into the containers which are used for storage. Sometimes these containers are barrels, but more often glass carboys. The containers are properly sterilized before the pasteurized juice is admitted. The bungs are also sterilized and coated with wax or some other preparation so as to make them air-tight. The juices are left in these storage containers until complete sedimentation take place and the liquid is clear. In some instances the pulp is not pressed, but additional sugar is added to it, and a low-grade sugared wine is made therefrom. When the sedimentation is complete the clear juice is siphoned off carefully, so as not to disturb the sediment, into bottles, which are then corked and sterilized as is ordinarily done for bottled goods. When white juice is to be made the crushed grapes are first pressed so as to secure the juice apart from the skins, and the subsequent treatment is the same as that just described. Bulletin 656 of the Bureau of Chemistry, issued May 8, 1918, gives detailed instructions for the manufacture of grape juice.