What caused my meringue to fall after adding cocoa? I made a very nice stiff batch of meringue for meringue cookies. I piped half of the batch on the cookie sheet and they looked wonderful (or at least they were nicely stiff, and I need to practice my piping). For the second half, I wanted chocolate, so I added Hershey's (dark) cocoa powder. I didn't measure the cocoa powder. As I whisked it in, the batch ( that had been wonderful) turned very runny. I tried adding more sugar in hopes of reviving it, but to no avail. So from the same batch I had nice white curly kisses and flat chocolate blobs. 

Was it the amount of cocoa powder?

Was it the fact that it was dark cocoa?

Was it the timing -- don't try to add something after it had been sitting about 10 minutes?

Something else?

I thought I finally got the consistency just right with the first half of the batch. --If only I had been satisfied with just vanilla...
Help?
It was timing.  If you want to make chocolate meringues, add the cocoa powder to the liquid egg whites, and then whisk it all together at once.  

Beaten egg whites are bubbles.  Don't add things to an already-formed meringue, as they will just cause the bubble structure to collapse.

Ever sprinkled sugar or cinnamon powder on a cappuccino?  Notice how the milk foam immediately collapses?  The same thing happened to your meringue.