Two separate experiments are performed on a gas enclosed in a piston-and-cylinder device, both starting from the same initial state. The result of the first experiment is to be used to predict the outcome of the second. 

a. In the first experiment, the piston is free to move, with the external pressure held constant. A small amount of heat is added to the gas in the cylinder, resulting in the expansion of the gas. The temperature of the gas is found to have increased. 

b. In the second experiment, the piston is not free to move; instead, its position is adjusted manually. In addition, the device is insulated, so that no heat flows to or from the surroundings. The piston is moved outward slowly, allowing the gas to expand by a small amount. Does the temperature of the gas increase or decrease?