Can you tell if a wadsworth pocket watch case is solid gold by the serial number inside the case itself

It's rarely possible to give any kind of definitive valuation without seeing a watch (pocket or wrist) in person, but it sounds like you have an inexpensive pocket watch that was probably made in the 1960s, less likely made in the 1970s or 1950s. The use of the term "antimagnetic" on the watch, as opposed to "17 jewels," suggests that the watch is powered by a 1-3 jewel pin lever movement, rather than a more expensive movement. These movements can keep quite good time, but they are not valued by watch collectors unless the rest of the watch is of compelling interest.

In terms of value, your pocket watch has more value as a piece of jewelry than as a vintage timepiece. Most watch collectors would not be particularly interested in your watch. In the United States, I've seen similar watches, in running condition, sell for $5-10 at vintage watch fairs. Around where I live (the Northeast), as a piece of jewelry, your watch may be worth twice that but not more. I cannot speak to pricing in other parts of the country or internationally.

If you go to Wikipedia and type in "
Joseph Johnson (watch maker)"
you will see there are a number of reference documents listed. The information you look for may be in one of these.

Gold filled is simply a very thin layer applied to the base metal case and will wear off over time. Solid 10K gold is an alloy that is mixed with gold throughout and will always retain it's color and never wear off. The solid 10K gold case contains a lot more gold than then the gold filled version and will cost more up front. However, the gold filled case will look awful in a year or two while the solid 10K case will last as long as you keep the watch and beyond.

The serial number is usually engraved on the movement. If you open the back of the watch, you should be able to see it.

I looked at the Hamilton pocket watch site (in might be helpful if you visit the site, simply type "" into your search engine and your will be able to examine photos of a number of movements).

The position and size of the number varies but it shouldn't take to long to find. One of the pictures I found impossible to see the number but the rest I found, although sometimes you had to look quite carefully.

The best tool to do it is watchmakers knife, but any proper knife with hardened steel blade can do the job. Make sure the blade is NOT flexible.
Check carefully the sides of your watch and you will notice the groove. Place knife blade into that groove and press it in. At the same time try to make a scooping turn to lift the caseback. Usually there must be underlayed caseback as well and it opens exactly in the same manner.
Make sure you do all this carefully and do not let the blade to slip or your watch will end up with nasty scratches or even damaged movement.
That job isn't a big deal, but requires some skill, so, BE CAREFULL.
Don't forget to rate, please.