After a mysterious force petrifies humanity and turns everyone to stone, Dr. Stone, A.K.A. Senku Ishigami, awakens and attempts to use his advanced scientific skills to revive those who were petrified. Senku's journey to save the world is aided by his unpetrified friends as well as new humans that have formed a primitive, caveman-like village.
Senku performs chemistry-based miracles throughout the series, constructing brilliant inventions out of the primitive technology that he has to hand, starting with a shelter in the trees, building his way up to incredible scientific feats such as working lightbulbs and chemistry sets.
Sulfa Drug
This 'miracle cure' contains multiple components that are near-impossible to obtain including electricity, sulphuric acid, and sodium bicarbonate. Senku's scientific mind makes it all possible by breaking down the steps into a road map that he and his friends can follow.
Illnesses in the primitive world would potentially be fatal, and the village priestess Ruri suffers from pneumonia, worrying her sister Kohaku and Senku's fellow scientist Chrome, who has feelings for her. The sulfa drug is used to cure her illness, making Senku seem like a miracle worker to the villagers.
Laboratory Glassware
Constructing a laboratory on its own is impressive in the Stone World, but the glassware that Senku uses is incredibly intricate and can only be created by a master glassworker. Luckily, Senku partners with elderly craftsman Kaseki, who is excited at the prospect of creating new and useful inventions.
Senku's chemistry requires accurate measuring since even one degree could be the difference between a life-saving drug or a poison. Creating accurate glassware required a lot of trial and error, with the glass smashing repeatedly as the materials were exposed to extreme heat.
Gas Masks
Collecting sulphuric acid is crucial to a lot of Senku's inventions, but the acid itself is extremely toxic. To neutralize the acid's effects, Senku created gas masks to keep himself and the villagers safe. Sulphuric acid is portrayed by the anime as a beautiful woman who suddenly becomes violent and witch-like the closer the characters get to her, indicating the acid's deadly true nature.
While the process behind creating the masks might appear to be simple, Senku took a massive risk in getting close to the acid, putting himself and his friends in immediate danger. The masks are a risk in themselves, as breathing too much due to panic could cause suffocation.
Cola
The mentalist and tactician Gen Asagiri requests that Senku make him a bottle of fizzy cola, as it is Gen's favorite drink, but also as a test for Senku, determining if Senku's abilities are legitimate and if Gen can trust him. As usual, Senku delivers, and Gen is rewarded with a genuine bottle of cola.
The primitive Stone World does not have such luxuries as cola—or, indeed, bottles—so Senku acing Gen's test and creating delicacies such as ramen and cola is impressive under the circumstances.
Electric Light
One of the sweetest moments in the series comes from the villagers setting up a Christmas tree covered in lights to enjoy around the holiday season. This is made possible by Senku's knowledge of the lightbulb, as well as Kaseki's patience and determination in creating lights that can not only decorate the tree but also light the villagers' homes.
The electric light also enables other inventions to work, such as the headlamp used when exploring dark caves to gather raw materials.
Cell Phone
Long-range communication is vital to the Communications Arc at the start of the strongest humanity has to offer, Senku's Kingdom of Science outwits their enemies by creating the cell phone, which enables them to out-maneuver even the strongest of Tsukasa's allies.
The cell phone requires headphones, a microphone, lightbulbs, batteries, and more, making this one of the most complex inventions in the series so far.
Record Player
Part of Gen's plan to win over the enemies in Tsukasa's Empire is to use the voice of Lillian, a famous idol from before the petrification, to convince them that the world is not limited to Tsukasa's primitive lifestyle. This plan is made possible by preserving Lillian's voice on a piece of glass from a bottle and playing the record through the cell phone.
The villagers hearing Lillian's voice through the record player is a genuinely heart-wrenching moment, as they are hearing the voice of their ancestors for the first time.
Hydroelectric Power Plant
Kaseki's masterpiece, co-created with primitive scientist Chrome, converts water energy into electricity. The power plant is at first powered by turning the wheels by hand, but Kaseki and Chrome advance its design and use the nearby river as a source of power.
Technology is all about creating faster routes to humanity's goals, and, with this invention, the Kingdom of Science can fast-track their victories and use electricity to power the lights in their homes.
Tank
Senku at first built an automobile-like transportation system, which the villagers dubbed "the steam gorilla" due to its size. But, in the war against Tsukasa, Senku was able to transform the automobile into a tank that could easily roll over traps and infiltrate Tsukasa's base.
Inventing the wheel might not be difficult for a 21st-century scientist, but creating the machine able to withstand an army out of nothing but wood and paper is certainly ambitious.
Refrigerator
As the Stone War comes to a close, Tsukasa is wounded, and Senku promises to heal him. Senku had previously found a way to freeze-dry food for long trips away from the village, and he uses a similar principle when freezing Tsukasa, hoping to find a cure for him in the future.
The refrigerator is full of complex science, and it might seem impossible to freeze food—let alone humans—in a primitive Stone World, and much of the process is skipped to keep the episode count short. However, Senku makes the whole process seem feasible with his step-by-step approach and calculating, scientific mind.