This can't be a normal Sammy because she says no milk or sugar, yet she is adding some kind of white powder. Maybe some narcotic to make the Admiral pliable to Sammy's wishes?
Have you heard of that story about the man who drank salted coffee for his whole life despite hating it, because he fell in love with his wife over salted coffee, and didn't want to confess to lying to her until in his will?
Samidare might be putting salt in there. It's good for the Admiral's health if all his other shipgirls are making him sweat in fear so much...
You don't just lose water when sweating after all.