Can somebody point me to a recipe for Ringers Lactate?  No, I'm not
planning on making my own, I'm just curious what's in it.

My cat had a bad bout of vomiting, ended up dehydrated, and the vet gave
him subcutaneous Ringers to rehydrate him.  I know it's an electrolye
solution, but can't find any details.  A google search turns up zillions
of references to what it's used for, but not what it's made from.