Sale for resale includes the sale of goods which will be resold in their original form, in an altered form, or as a part or ingredient of another article. A sale of goods which the seller knows, or has reasonable cause to believe, will be resold after processing or manufacture is a sale for resale. Thus, sales of parts with the expectation that they will be incorporated in aircraft and that the aircraft will be sold clearly are sales for resale. (Arnold v. Ben Kanowsky, Inc., 361 U.S. 388.) Similarly, the sale of lumber to furniture or box factories, or the sale of textiles to clothing manufacturers, is a sale for resale even though the goods are resold in the form of furniture or clothing. The principle is also illustrated in cases where the article sold becomes a part or an ingredient of another, such as scrap metal in steel, dyes in fabrics, flour in bread and pastries, and salt in food or ice in beverages. (Mitchell v. Douglas Auto Parts Co., 11 WH Cases 807, 25 L.C. Par. 68, 119 (N.D. Ill., 1954).) The fact that goods sold will be resold as a part of a service in which they are used or as a part of a building into which they are incorporated does not negate the character of the sale as one “for resale.” (Mitchell v. Furman Beauty Supply, 300 F. 2d 16 (CA-3); Mayol v. Mitchell, 280 F. 2d 477 (CA-1), cert. denied 364 U.S. 902; Goldberg v. Kleban Eng. Corp., 303 F. 2d 855 (CA-5).)