What was advertised in a colonial newspaper 250 years ago this week?

“To be had at the Heart and Crown, Justices Blank Certificates.”
For printers Thomas Fleet and John Fleet, their business was most widely recognized by the emblem of a Heart and Crown that appeared in a rococo-style cartouche in the masthead of their newspaper, the Boston Evening-Post. A sign featuring the Heart and Crown also hung outside their printing shop, announcing the location to residents and visitors alike. In effect, the Heart and Crown became the Fleets’ logo, a unique device associated specifically with them, their printing shop, and the goods and services they provided. The Heart and Crown was so widely recognized as an alternate means of identifying the Fleets’ printing shop that this advertisement did not include their names or the street on which they were located. They expected readers to recognize the Heart and Crown and associate it with their printing shop.

Printed blanks, such as indentures and bills of lading (what we would call blank forms today), were among the goods produced and sold by the Fleets. This advertisement pertained to a certain kind of blank: “Justices Blank Certificates, For Persons who bring POT-ASH for Sale.” It appears that such blanks were used to regulate the production of potash, but they present a bit of a mystery. Eighteenth-century readers would have needed as little explanation for “Justices Blank Certificates” as they needed for “at the Heart and Crown,” but the meaning and familiarity have faded over time.
This advertisement demonstrates the ephemerality of many items printed in early America. “Justices Blank Certificates” were used so often that printers produced them in sufficient quantities to merit advertising them, yet unlike other types of printed blanks they do not seem to have survived to the twenty-first century. At least, I have not been able to turn up any examples. (Please let me know if you know of any!) Perhaps some are lurking in libraries and historical societies and have yet to be cataloged or digitized.
I have long suspected that most business forms that came off of printing presses in the eighteenth century have not survived. A precious few that were saved testify to their existence, as do the entries in printers’ ledgers that suggest that such items were frequently printed. This advertisement causes me to question how extensively commercial printed items – both printed blanks and advertisements (handbills, trade cards, billheads, broadsides) – were created and discarded in the eighteenth century. Even if they no longer exist in physical form, we know of some from advertisements and account books, but many, many others likely remain unknown. Those still extant are extraordinary remnants of a vibrant assortment of commercial printed items that circulated in early America.