Letter, 'To improve vegetables' by Mr Ludwig to Jos [Joseph] Hartlib Ludwig discusses red dyes made from various fruits, vegetables, and insects including prickled peare [prickly pear], summer island redweed, cochenill [cochineal]. Subject: Botany / Industry Published in Philosophical Transactions as 'Observations - Concerning cochineel, accompanied with some suggesti­ons for finding out and preparing such like substances out of other vegetables'. [1668]