医院用过的X光片每年都要处理一些，印刷厂照相制版用过的胶片有好多被丢弃进垃圾堆里。只要收集到上百克废胶片，对其进行回收所制得的硝酸银就够普通中学实验室用很长的时间。经过定影的胶片所含的银虽然以单质存在，但用以制取硝酸银时，不宜直接用硝酸浸泡废胶片，那样耗费 Hospitals have used X-rays a year to process some, and many of the films used in the printing press have been discarded in trash. As long as the collection of hundreds of grams of scrap film, its recovery of silver nitrate made enough ordinary high school laboratory with a long time. After fixing the film containing silver although the existence of a single substance, but for the preparation of silver nitrate, it is not appropriate to use nitric acid soaked scrap film, so cost