Subject: Marble cleaning formula needed

Does anyone have a formula that meets conservation approval to clean old
yellowed marble from the 1890's that has been neglected.Years of dirt to
remove and yards of marble to clean in an old soda fountain /drugstore
counter tops .Of course the design department needs it yesterday!!!
Perhaps someone has their grandma's old time household formula book like Spon's
Household Formulae.
I've tried Triton X-1009negligable results),mild solution of ammonia
(removes some dirt). It was suggested to wet sand with 600 paper in
combination with Triton x 100 .This worked well on my sample but felt I was
being rather too intrusive!
Poultices would take too long.I am aware marble cutters have commercial
products but will nopt devulge the formulae.
Your suggestions within the relm of conservation ethics would be very welcomed!

Regards
Len Hambleton-Objects Conservator
North Carolina Museum of [log in to unmask]