How to count up elements in excel

Question

So I have a column called chemical formula for like 40,000 entries, and what I want to be able to do is count up how many elements are contained in the chemical formula. So for

Answer 1

I've had a stab at doing this in a formula nad come up with the following:

=IFERROR((MID($C18,FIND(D17,$C18)+1,2))*1,IFERROR((MID($C18,FIND(D17,$C18)+1,1))*1,IFERROR(IF(FIND(D17,$C18)>0,1),0)))

It's not very neat and would have to be expanded further if any of your elements are going to appear more than 99 times - I also used a random placement on my worksheet so the titles H,C and O are in row 17. I would personally go with Jamie's answer but just wanted to try this to see if I could do it in a formula possible and figured it was worth sharing just as another perspective.