How to determine required voltage of a lightbulb
If you already hooked it up to \$110\$ Volts and it did not blow up, then you should now measure the actual voltage being supplied and measure the actual current going through the bulb at the measured voltage.

$$
\text{Power in Watts} = \text{Volts} \times \text{Current} 
$$

So if you measure the Voltage and Current and multiply those two quantities together, you will get the Wattage at \$110\$V nominal.. If it's near enough to \$25\$ Watts then you can assume it's a \$110\$ Volt lamp.