Unit 1

This bichromate positive was then placed on a sheet of zinc covered in lithographic ink, and put through a printing press three or four times. After removal of the paper, the zinc plate was washed in a tray of hot water (containing a small amount of gum), using a camel-hair brush to remove all the soluble bichromate combined with ink. ................
................

In order to avoid copyright disputes, this page is only a partial summary.