HC Evans Blockout Ink
This is an original vial of blockout ink, used to mark cards, sold by HC Evans, up until 1961. As the name would imply, the ink was used to put blockout work on playing cards. The vial of blockout ink was sold with a small instruction sheet and a paintbrush.
It should be noted that this particular ink is very likely to contain some hazardous chemicals. Many of the blockout ink recipes from the earlier part of the 20th century list carbolic acid (aka phenol) as one of the necessary ingredients. It is very likely that this ink contains a very small amount of carbolic acid, which is toxic even in small quantities and very likely to cause cancer. By today's standards laboratory technicians must wear full-body protecting to handle carbolic acid in a controlled environment. If you ever get a hold of on of those inks, do not under any circumstances open the vial.
Below is a scan from an old HC Evans Blue Book, crooked gambling catalog, showing the listing for this blockout ink. Note that the illustration in the catalog shows a vial that is slightly different in appearance, from the vial that they actually sold.
More about blockout work can be found in our chapter on marked cards.