Jo Nesbo 
Doctor Proctor»s Fart Powder: Time-Travel Bath Bomb [EPUB ebook] 

The Fart Powder was such a successful invention that Doctor Proctor couldn»t stop there. Next up: a Time-travel Bath Bomb. Throw the Bath Bomb in the tub, lather up and imagine where you»d like to visit. The battle of Waterloo? No problem. The French Revolution? Let»s go! Doctor Proctor has plans for this new invention. Years ago he lost his true love, Juliette Margarine, and now he wants to change the past and win her back. But when his plan goes awry, it»s up to Nilly and LIsa to travel in time and save the day.