What is "Glass-o-reen"?

Sounds like it might have been some locally concocted dessert or beverage. Some web searching indicates that glycerin was an ingredient in various foods in the late 19th century. Do you have any idea where the photo was taken, or the name of the parlor?

Oh boy that's a doozy! Maybe a way of spelling glycerine but in way people could prounounce it? You'd use it to make the ice cream softer, soft serve!