Sidenote:
Anhydrous copper sulfate is a great desiccant. It is white but will progressively turn blue as it absorbs moisture. There are mechanical watches that contain dry cartridges filled with copper sulfate. Those watches are also filled with a noble gas to not only make the dry cartridge functional but to also prevent lubricant oxidation. Through a little window you can see the color of the copper sulfate. Once it shows a strong blue a service is required. If the indicator turns spontaneously blue you can presume a leaky seal and you know moisture ingress has occurred.