can you please tell me what this gun was chambered for?

Question

Hopkins & Allen Revol   Hello Charles Gage,
I have a Hopkins & Allen safety police top break 5 shot Revolver
serial # S 9899  patent date Aug. 21 1906 I would like to know what the proper cartridge is for this gun. it was sold to me as being .25 cal that couldn't be, so i figured it to be .32 short center fire. but after viewing  several .32 cal pistol cylinders I now believe that it is chambered for .38 short S & W center fire can you tell me by the serial number what it is exactly .32 or .38, rim fire or center fire, black powder or smokeless, and if the modern day ammo S&W short center fire will work in it. (proving the gun has been checked by gunsmith for safety and  cylinder timing). Thank you for any and all info you can provide.

Answer
Hello Ronald.
  First, Ronald, the 'competent licensed gun smith' you take it to will be able to answer your question as to caliber. The picture you attached, definitely rules out anything smaller than a .32 S&W ( not .32 Colt,.32 H&R Magnum, nor any other designation ), but I can't say if it is a Short or Long. The .38 S&W ( not .38 S&W Special, .38 Long Colt, nor any other designation ),was only manufactured in .38 S&W cartridge, and this is how it reads on the box. These cartridges were all centerfire.
  You ask if it is was manufactured to fire modern smokeless or black powder ammunition. Most centerfire cartridges were loaded with black powder into the late 1800's, when semi-smokeless powder became popular. This still had black powder characteristics as a lower chamber pressure than smokeless, but with much less smoke when fired. Winchester manufactured this type powder up to 1947. This is why many people say that older firearms were built for smokeless powder with lower pressure than modern smokeless.
  Although the Iver Johnson Arms & Cycle Works Company revolver is not the same as the Hopkins & Allen, they are closely related as to basic manufacture. The Iver Johnson revolver did evolve from black powder to smokeless with their Third Version Safety Automatic revolver in 1909. This was still the lower pressure smokeless powder. Many, however, do shoot modern smokeless in these older revolvers. I suggest you check with a professional re-loader for varying case pressures. This I will leave up to you. There are some Experts on this site you might ask.
  I hope this information will help you decide whether you want to shoot or retire your revolver. Charles Gage