How to Change Icon size in the Unity Launcher

Either install compiz-settings-manager from Ubuntu Software Center or open terminal and paste the following two lines.
$ sudo apt-get update
$ sudo apt-get install compizconfig-settings-manager
After installing compizconfig-settings-manager, click on the shut down icon at the far right-hand of the top panel and then click on the “system settings”. In system settings in the Personal group, look for compiz-settings-manager and click on it.
In the resulting window look for Desktop and then unity plugin. Click on it. Next click on “Experimental”. In Experimental look for Launcher icon size. It is a slider. The icon size is set at 48 but can be reduced to 32. There are other things such as panel transparency which can be altered.