Is it illustrated?

http://dogbert.abebooks.com/servlet/SearchResults?bx=off&sts=t&ds=50&bi=0&pn=jarrolds&an=sewell&y=11&tn=black+beauty&sortby=1&x=113

Those are all Jarrolds publications. As you can see, the 1912 with illustrations by Cecil Aldin appears to be the most sought-after edition.

At a guess I'd have to say you have a late reprint of the 1890 1st edition.

. ------------------------------------------------------------------------------------------------------------------------------------------------------Whomever you may murder, there's no police like Holmes.
Σ Ψ Δ
σ ψ δ