Well, I tried to add that functionality to the ancient nonstandard code that lies at the base of all chemistry.  Kidding aside, I was running into runtimes and didn't understand all of what the code was doing.  I'm sure I could get it *eventually*, but is that really in the scope of this pull request?  It's been the way it is for a long time.  Instead of snowflaking around it, I'm at least using the existing reagent_container functionality.