Nick put the gauntlet in his realm before leaving the workshop to go find a few lesser creatures like rats and beetles to use as test subjects. He obviously wasn't going to walk around with something like that in the open as literally everyone will be able to see it and get curious. The professors would definitely notices that something was wrong with it almost immediately. It would only take a small leap in logic to figure out that he was doing something related to souls which was an almost taboo subject to study.-
It wasn't illegal so long as one avoided human experimentation but that didn't mean it didn't have a heavy aversion attached to it. So rather than deal with that Nick simply chose to secretively collect a few creatures no one would miss and use their souls as the basis for his experiments. There was one thing that Nick knew already thanks to Nazgul which was that not all souls were the same. For example the souls of animals without intelligence such as rats and beetles were "pure" and white as they cannot do dark arts if they can't know what that is.-
Intelligent souls like those of the acromantula were silver , white and/or some other shade of color based on their innate traits and whether they did dark arts. Acromantula souls by their manmade monstrous nature were silver and purple for example. Nick wasn't going to capture an acromantula quite yet though as he wanted to get a real feel for handling the gauntlets first. It wasn't particularly hard to collect a dozen or so rats since he merely needed to find a warm semi-isolated spot in the castle and force them out of their burrows.-
Generations of rats had lived and bred in Hogwarts so the had in a small way evolved to the climate of the school and thus had habits that he could exploit. Beetles were just as easy to find as the hardy creatures dug under stones into the earth when winter came to stay warm. Nick simply flipped a few rocks and got to collecting. Nobody found it odd that he was doing this either as so many things called for beetle eyes that shops sold them by the scoopful(A/N: that's an actually canon thing). As for the rats he captured that too was a regular occurrence for students in the higher years as they needed test subjects for various magical things. -
Nick brought the creatures into the realm and slipped on the gauntlet smoothly as it clung to his hand snuggly. 'Lets start with a beetle.' he thought as he plucked out one of the small insects with his uncovered left hand. Carefully he pinched the tips of his fingers on his right hand around the beetle and to his surprised the gauntlet sank into the beetles body like it wasn't there. It stopped once Nick felt a sudden spike of "feelings" was the best way to describe it.-
It was as though he was seeing something without using his eyes in roughly the shape of a beetle in between his fingers without actually seeing it. It was a disorienting experience to say the least and it was only after he lifted his and and extracted the soul from the beetle that he could actually see the soul. It was a bright white mass of shapeless energy despite what his new sense was telling him. Checking the beetle Nick found that the body was still very much alive if motionless and he wondered if putting the soul back would make it as if nothing had happened.-
So that was what he did and as he had thought the beetle continued doing what it was before he extracted it's soul. This was interesting as Nick wondered what would happen if he took out the soul and then killed the body before trying to put the soul back. He thus repeated the test except this time he used a tiny amount of electricity to stop its bodies heart. He waited a few moments before trying to place the soul back into the body but this time there was a different reaction.-
The beetles body twitched horribly for a few minutes before the corpse exploded and he assumed the soul dissipated. 'A dead body can't hold a soul then how do inferi work?' Nick pondered with a frown. Inferi were supposedly created by trapping a soul in it's dead body that was then forced to serve the one who killed them. Either this wasn't actually how that worked or there was something about the process that was different than what he just tried. Noting this disparity Nick banished the exploded remains of the beetle and grabbed another.