Nitrate film was the first motion picture film stock which was manufactured in 35mm, a gauge standardized by Eastman Kodak. Made of cellulose nitrate, it was highly flammable and was replaced by a cellulose acetate film stock, aka safety film, ca. 1951 for theatrical films. As early as 1919, 35mm acetate film was used in educational and community settings and for all 16mm, 8mm, super 8mm film. Nitrate film, although remarkably stable under the right environmental conditions, deteriorates becoming brittle, sticky, and finally disintegrating into a brown powder. It is unlikely that you will find nitrate motion picture film but if you think you have, contact an archives for advice.