If you hit a patch of black ice you might start sliding a little but do not slam on the brakes, over react etc.
Remain calm, slow down and if it's just a patch of black ice then your car should not go off the road and you may not have to slow down for too long.
Black ice is called black ice because it's hard if not impossible to see because it blends in with the asphalt that is black.
If the road is really icy then you will need to remove your foot from the accelerator and slowly depress the brake pedal to come to a stop.
If your car starts to skin on ice the first thing you should do is remove your foot from the gas pedal and allow the vehicle to slow down.
Then as you're removing your foot from the gas pedal and the vehicle begins to slow down be sure to steer away from the skid.
And do not over steer.
Do not slam on your brakes when you slide on ice as it can cause you to slide even more and spin out of control.
Sliding on ice can be scary but you just need to be calm, be aware of your surroundings and slow down.
If it's icy out you should avoid driving on the icy roads if possible.
However if you do need to drive on the icy roads be sure to drive slower and stay further back away from other vehicles so that you have more time to stop.