William walked towards the classroom on the first floor, and for the day to come, William used the alchemy knowledge he had learned to make a lot of knick-knacks.

Soon, he was in front of the stairs on the first floor that led to the underground classroom and dungeon.

William took out some orbs from his magic bag that looked like golden snitches.

Then the balls were secretly hidden at the top of the staircase, and then arranged all the way to the innermost empty classrooms on the left side of the first floor.

The row of classrooms on the first floor of Hogwarts Castle, across from the Great Hall, was rarely used, and was mostly idle, giving William an opportunity.

The shape of the small balls that William placed just now was indeed inspired by the Golden Snitch.

You know, when William was sweeping the goods in Diagon Alley. At the Quidditch Shop he didn't just buy a few broomsticks, he also bought some Golden Snitch for research.

Whether in his past life or in this life, William was full of interest in this magical little ball.

However, this time, the balls that William made that looked like golden snitches were actually a magic detector used to detect the magic around them.

As long as there is a fluctuation in the surrounding mana, it means that someone has used magic, and the detector will send a signal to William.

According to Hogwarts rules, young wizards are not allowed to cast spells in the hallways, and everyone should go to the Great Hall for Halloween in the evening.

At this point, the magic fluctuations that occur in that position could only be caused by Quirrell using magic to control the troll.

Through this method, William will be able to know that the troll has been released immediately.

However, since the range of detection and conduction are not too far, William cannot be too far away.

William planned to read in the nearby empty classroom while waiting for the signal to sound, so that William could rush to the rescue as soon as possible.

Through this heroic rescue of beauty, I found an appropriate excuse for myself to go to the all-in-demand room on the eighth floor.

William set everything up, then turned to leave, walking towards the next class.

"Come and sit here, William. I've got a seat for you. What did you do? Why did the person disappear in the blink of an eye just now? ”

As soon as he walked into the classroom, William was greeted by Terry's curious inquiry.

"Ah, another black cat stopped in front of me just now. I," William said nonsense that no normal person would believe.

"Really! Did you meet Professor McGonagall again? Do you think she likes to be a cat and wander around the castle? ”

Before William could finish his sentence, Terry interrupted him impatiently.

Merlin, did you trade your Quidditch skills for your IQ?

Do you believe all this nonsense?

Or have these weeks of Quidditch training broken your brain?

William didn't expect that the black cat terrier he casually mentioned was actually taken seriously by Terry.

It seems that next time he will change the stalk, William can't help but be a little curious when he thinks of this, he wants to try to see how low-level the nonsense is, so that Terry can realize that he is talking nonsense.

The afternoon passed quickly, and as the bell rang for the end of class, William casually made up a reason to ask his roommate to get rid of.

Thinking about walking to the first floor alone, he found an empty classroom, took out the alchemy notes of the ancestors, and began to read them seriously.

The notes weren't thick, and William had actually read them several times. Through this notebook and some cobbled alchemy knowledge, William was able to produce such an intricate alchemical product as the magic sensor, which would be enough to make the outside world jaw-dropping if it were reported.

Because the golden snitch is only the size of a walnut, and its diameter is only five centimeters.

William needed to engrave the inside of such a small ball with a variety of alchemical symbols, which seemed to wizards to be fanciful.

Thanks to William's identity as a traverser, he was able to use the scientific tools invented by Muggles.

With the help of a magnifying glass, William used a specially made front end to enchant the carving knife of the Shrinking Charm, accomplishing what seemed impossible to wizards.

However, because the size is too small, and William's knowledge of alchemy is limited, William can't engrave too many inscriptions, which leads to a small detection range and transmission range of the Golden Snitch Detector.

William had to arrange a lot of detectors at the top of the stairs, and several special conductors along the way to successfully transmit the signal to William, who was located in the empty classroom inside.

So in William's view, this is just a very immature invention, and there is still a lot of room for improvement.

However, this was already the limit of what William could do, which made him feel that his alchemy should have reached a bottleneck.

You must know that from ancient times to the present, learning alchemy has attached great importance to inheritance. Without a good teacher to guide the way, it is difficult to achieve anything on your own without self-study.

However, Hogwarts did not offer alchemy courses, and the closest course was the ancient magic script, which could only be taken in the third year, which made William very depressed. There are so few masters of alchemy in England that there are actually only a handful in the whole of Europe.

Only in Egypt, due to the local history and culture, coupled with the importance that the Egyptian Ministry of Magic attaches to the inheritance of alchemy.

The alchemy inheritance there is still very intact, and it can be called the most prestigious alchemy holy place.

There are many alchemists who have come out of it from ancient times to the present, and the most famous of them is Hermes, who created the "Jade Record", a great alchemist and a powerful wizard.

In his time, no one could match it in alchemy.

In Egypt at that time, alchemy did not know what it was like.

Even on the coat of arms of the International Association of Magicians, the star surrounded by the ancient Egyptian word represents Hermes.

If you have the chance, you really want to go to Egypt.

Europe is not without alchemists, the most famous is Nicolamet, who successfully made the Philosopher's Stone.

It is said that he discovered some of the documents left behind by ancient Egyptian sorcerers, and based on these materials, he succeeded in crafting the Philosopher's Stone, turning mercury into gold, and allowing himself and his wife to live in a near-immortal manner.

You know, he was born in 1330! Now he is more than six hundred and sixty years old. Dumbledore was in front of him, and William reckoned that he should be like a child.

It's just a pity that Lemay hasn't taught alchemy for a long time, in fact, Lemay has been living in seclusion with his wife for many years.

You know, as a Frenchman, he once taught alchemy at Beauxbatons for a while.

This is also the reason why Beauxbatons can later be ranked as one of the top three magic schools in Europe, and the influence of an alchemist is still extraordinary.

Now that I think this is a little too far away, I should write to my father and ask my father if the ancestor left any other notes.

William was thinking in the empty classroom when suddenly, the receiver began to buzz.

At the same time, outside the classroom, there was a sound of heavy footsteps, and William could even feel that the floor of the classroom was shaking slightly.

A sour smell that seemed to be something that could only be felt after ten years of changing socks slowly wafted in from the outside