The invention of liquid soap is not a major invention by itself but liquid soap combined with its easy to use dispenser is what made it a very successful product.
William Shepphard from New York discovered that when a large amount of ammonium bicarbonate was mixed with soap, it resulted in a soap with the consistency of a treacle. He patented liquid soap in 1865. But it was not until 1980 that liquid soap began to be used for domestic purposes. Until then it found use only in industries.
The Minnetonka Corporation of Minnesota began to market the product under the brand name Softsoap in 1980. The key to the success of the soap was the dispenser which essentially had a small plastic pump over the bottle. The pump made dispensing of the liquid soap a whole lot easier and soon softsoap became widely used at homes.
Minnetonka used a unique strategy for beating its competitors. It bought all the plastic pump dispensers available in the country. Their strategy worked! Minnetonka captured the market completely. Eventually in 1987, they sold the liquid soap brand to the Colgate company which continues to market Softsoap.