What is a science lost to history?
??????????
The only thing I can remotely think of is alchemy. Some today would consider alchemy to just be an early form of chemistry (and chemistry is still very much studied), others simply a pre-science thing, existing before modern science began.
There are DISCIPLINES (generally not sciences) that have largely been in a sense reassigned or just now handled differently. Geography for example was a specific discipline until maybe 50-75 years ago; colleges had a Geography Department and you could get a degree (even Ph.D.) in that. Today, it's been absorbed by other disciplines. Public Speaking is another example, today that;s typically a part of "Communication." And some things are just named differently now; "Naturalism" is now regarded as biology; a "naturalist" then is called a "biologist" now. But it's not "lost."
But there are three "sections" of science: Math, biology and physics. And they are very much still taught. Some sub-topics might go by different names today... and new subcategories are added often.... but nothing has been "lost."
.