grammar - Omitting repeated definite article

Is it grammatically correct to omit the second "the" in the sentence

The viscosity and the density of water characterize its speed.

and write instead

The viscosity and density of water characterize its speed?

Answer

Repeating the article can avoid ambiguity when adjectives get involved. "The black dog and cat" might mean "The black dog and the black cat" or "The black dog and the cat [of any colour]." "The black dog and the cat" clearly associates "black" only with the dog.