During manufacturer, the inside of the tube is dusted with talc or similar to stop the sides sticking together.
Moisture in the air during tube inflation condenses and forms paste. This is what you have found.
If you still have the receipt, take the bike back for a refund.
You are too stupid to ride a bike. I don't want jerks like you on the same streets as others.
How in hell did you manage to learn to use a PC?