The man who found Mercury sulphide and invented Soap!
Chakrapāni Dutta
Chakrapāni Dutta was a Ayurveda physician and sanskrit scholar,
He was born in the village of Mayureshwar of Bangal in the Brahmin family.
Chakrapāni discovered mercury sulphide. The credit for inventing soap also goes to him, he used mustard oil and some alkalies as ingredients for making soap.
His best known books on ancient medical science are Chikisasamgrah (collection of medical practices and procedures), Dravyguna (Properties of plants), and Savsasmgraha (collection of the essence of thing), he wrote many books on Ayurveda and medical science.
The great Indian mathematician who discovered the height of Mount Everest!
Radhanath Sikdar was born in Bengal in 1813. He completed his studies in mathematics from Hindu School (Presidency University)
In the year 1831, he got a job in the Survey of India as a computer (which means person who calculate). And he was tasked with the task of finding the height of peak 15 even bigger than Kanchanjanhga peak and with his hard work, he found the height of 'peak 15' to be 8839 meters.
With the help of trigonometry and special equipment. He told this to Andrew Scott, director of the Survey of India, who confirmed this in a long time and, on getting it right, sent a proposal to name peak 15 after his guru Sir George, which was also approved.