WW2 Navy medical jargon question

I am transcribing the Navy Service Diary of Leslie Clifford Lewis, 625-49-16, Storekeeper Second Class (SK/2). Some entries in Sept, 1943 have me asking a question.

"21st.: I lost my breakfast this morning but felt better after that. We have passed Florida and should be nearing Cuba. Tonight Dan and I are sleeping out on deck.
22nd.: We had a cool nights sleep last night. It is just too hot below. We sighted land today and should be in Guantanamo, Cuba by morning. The doctor gave me some “black & white”.
23rd.: Water ran down the deck from the water fountain and got my bed all wet and the black & white got me up at 2:30 AM so didn’t enjoy my night. This morning we pulled into a bay in Cuba. Nothing much to see. I got off a few letters. We left in the afternoon for Panama Canal."

I assume "black & white" is some kind of sea sickness medicine, but does anyone know what it is?

Thanks, Paul

 

Black and white could mean Movie Reels but that is what I saw when I looked it up. I could be wrong but Hopefully I am right for your sake and mine

 

Could be milk of magnesia and cascara. Just a guess from my medical background.