During the reign of King Alongmintaya’s fourth son King Vadong , there were historical records about the ‘Thway Sayl’ or ‘Blood-Wash’ lake located near the north gate of Shwedagon Pagoda.
In 1796 during the reign of King Vadong, Captain Hiram Couks, the British ambassador who came to Rangoon to control the English trade, noticed the medicinal properties of the ‘Blood-Wash’ lake. In Hiram Couks’s ‘Journal of A Residence in the Burmhan Empire’, Couks said that there was a lake near the northern gate of Shwedagon Pagoda.
The water in that lake is medicinal. It was recorded that both indigenous peoples and Europeans knew about medicinal properties. Couks did his own research on the medicinal properties of the this lake.
In the record book written by Couks, he also studied and recorded the nature of the soil and rocks around the location of the blood pool. In Captain Couks’s account, there is a thin layer of silica-rich soil on the top of the hill near the blood pool. The second layer is rich in iron and laterite.
The third soil is a mixture of iron-rich red soil and silica-rich soil, which contains more red, yellow, and blue iron ores. The fourth layer contains white clay. The fifth layer contains a large amount of iron ore and is rich in sulfuric acid. The sixth soil layer is gravel. The amount of iron ore and the amount of sulfuric acid is higher.
In Captain Couks’s record book, the blue gravels in the sixth layer, formed by the erosion of the monsoon rains to the bottom of the water, formed natural copper ore when exposed to the sun. The rocks around the lake are sandstone; a thin layer of red iron ore is found on the rock face in many places.
When these four come into contact with the air, they turn into yellowish white powders. The mud that settled in the pond When the water dried up, a yellow bronze remained on the surface of the mud. It was also recorded that the presence of carbon dioxide was clearly seen in the cavities between the rocks.
Captain Couks also tests the water in the lake in details. Regarding his findings, Couks said that the iron in this water is dissolved in iron salts by reacting with sulfuric acid. In addition, a small amount of magnesium oxide and potassium chloride salts are dissolved. It was identified and recorded as mineral water.
Burmese evidence also supports Captain Couks’s findings that the water from the lake is medicinal. This evidence is in the decree of King Vadong issued on November 5th, 1811: “Let the water from the ‘Blood-Wash’ lake be delivered to Han Thawti Main City Councilor”.
There is no evidence that the water from the lake cures any disease. It is found in the records that it contains medicine. Some local people say that this lake has won victory in battles with enemies, hands and swords. Blood was smeared on the spears, so it was a lake where the blood was washed, and it was called the “Blood-Wash” or “Thway Sayl” lake.