The Soap Dispenser: A Measured Dose Between Two Plungers

Rose's objects are "a simple device which will be adapted to conveniently dispense measured quantities of the soap", with parts "so arranged as to avoid waste of the soap due to leakage." A container 10 sits in a holder 11 on a bracket 12 on the wall. Below it is a horizontal cylinder 14 with removable heads 15 and 16. Inside are a plunger 22, pushed by a knob 24, and a plunger 20; springs 25 and 26 act on them. Soap from the container reaches the cylinder through an opening 27 (the patent calls it an outlet — it is the container's) and leaves through an outlet 28. "By pressing on the knob 24 the plunger 22 is moved toward the right in the cylinder and compresses the spring 26. A slight movement of the plunger 22 covers the outlet 27", and the soap between the plungers "act[s] as a liquid piston" to move plunger 20, which "uncovers the outlet 28 and permits a definite quantity of the liquid soap to be discharged". When the knob is released, "the separation of the plungers by the spring 26 produces a suction in the space between the plungers" that draws in the next charge.

Measure a store-bought pump soap dispenser first: pump ten times into the graduated cylinder and divide to get the dose. Take the pump apart and find its plunger, spring and the two one-way valves that do the job of Rose's inlet and outlet ports. Then build Rose's version from a syringe barrel as the cylinder: drill an inlet hole near one end and an outlet hole further along, fit two short plungers cut from syringe plungers with a spring between them, and feed it from a bottle above. Mix soap from the liquid soap kit, press, and measure each dose. Change the spring gap and measure again.

**William H. Rose** of Jersey City, New Jersey, filed US 1,164,754 on 8 March 1915; it was granted on 21 December 1915. **Honest limits.** The bores and gaps in the notebook are examples; the patent gives no sizes. Modern pump dispensers use one-way valves rather than Rose's sliding ports.