The first chocolate bars were gritty and bitter because they were not ground long enough to become smooth.

Before the 1800s, people mostly drank chocolate as a liquid. In 1828, a chemist named Coenraad van Houten invented a press to remove fat, called cocoa butter, from cocoa beans. In 1847, the company J.S. Fry & Sons mixed this fat back into cocoa powder and sugar to make the first solid bars.These early bars felt like sandpaper on the tongue. The sugar and cocoa pieces were too large and uneven. The fat was not spread evenly through the mix, so the chocolate did not melt easily at body temperature.Rodolphe Lindt changed this in 1879 when he left a mixing machine running for a whole weekend. This machine was called a conche. It used heavy rollers to grind the chocolate into tiny particles. These particles became smaller than 20 microns, which is too small for the human tongue to feel as grains.The long mixing process also removed bitter acids from the chocolate. It coated every tiny piece of cocoa and sugar in a thin layer of fat. This created the smooth, melting texture found in modern chocolate bars.