This section is from the book "The Boy Mechanic Vol. 2 1000 Things for Boys to Do", by Popular Mechanics Co.. Also available from Amazon: The Boy Mechanic, Vol2: 1000 Things for Boys to Do.
The inflation of rubber balloons may be accomplished with manufactured gas by using the simple pipe arrangement shown in the sketch. The connection A is for the gas hose, which is similar to those used for a table lamp. The gas bag B is a football or punching bag connected to the pipe as shown. This receives the gas as it is let in by the valve A. The toy balloon C is connected to the pipe in the same manner and the valve D used to regulate the flow of gas. The gas is easily pressed out of the ball into the balloon.
Ill: Pipe Arrangement, Punching Bag and Valves to Admit Gas to a Toy Rubber Balloon
As hydrogen gas is much better than the manufactured gas, it is best to use and can be put in the balloon in the same manner.