It seems that the Romans would dry clean their laundry with ammonia derived from urine. Considering the source of the ammonia, and the smell of pure ammonia, I find it hard to believe that this connection was ever made. How did one come to the conclusion that soaking clothes in a stinky fluid derived from urine would make it cleaner?
Urine was also widely used for improvement of leather. It was quite natural to try and put in it something else. Hmm... But I wouldn't call it "dry clean" :-)
Ancient cultures had so few chemical reagents to try, that they tried everything on everything. For example, they hardened steel in urine, too. Tried multiple materials to see what urine is the best for - old, new, that of a goat or of a man? What man? young or old? And so on.
"Ammonia" can mean on of two quite different things: Pure NH3 (ammonia-the-substance) which is a gas at room temperature but which is readily liquefied under pressure, and the household cleaner which is a few percent of NH3 dissolved in water, often with some detergent added (ammonia-in-water)
The Romans had the latter, but did not have the former which was not made until the mid-1700s.
I don't think ammonia-the-substance could be used for dry cleaning, but you never know. In any event, all the Romans had was ammonia-in-water which by definition couldn't be used for drycleaning.
The Romans didn't have "dry cleaners", but their politicians discovered that a clean white toga helped make them the center of attention in ant gathering. Rome did have fullers, the specialists who added body and stability to newly woven fabric. Given time, the fullers could get the pale grey of newly woven wool fabric. This could make up into the "toga candida" which announced an aspiring office holder's ambition and helped him stand out in the sea of somber togae, which were much more command to ...