which was the kingdom seal, on one side and the regal seal of each reign on other side. King Rama I had the Unalom Lotus Seal imprinted on the Photduang of his reign. King Rama II used the garuda seal. The seal of King Rama III was in the shape of a palace. The weight units of Photduang were Tamleung (, 60 g of silver), Baht (, 15 g), Salueng (, quarter of Baht), Fueang (, half of Saleung) and Phai (, quarter of Fueang). Different currencies were used in Lanna and Lao Kingdoms. In Laos, the Lat silver bars were used. Photduang were also accepted in those regions. Though Photduang currency existed, the barter exchange remained prevalent. In the reign of King Rama II, the royal court distributed Biawat stipends to government officials in the form of white clothes. Some taxes were collected in form of commodity products. Before Bowring Treaty of 1855, most Siamese economic transactions were done through barter exchange. After Bowring, the Siamese economy expanded in scale and led to monetization of the economy. Cash in the forms of Mexican real, Dutch guilder, Indian rupee, Japanese and Vietnamese coins flooded into Siam. Siamese people were reluctant to switch to coin usage and stuck with their Photduang. Foreign coins were melted and re-cast into Photduang silver bullets. However, casting of Photduang required craftsmanship and did not meet the demands of Siam's growing economy. Government had to declare foreign coins legal for usage inside Siam in 1857. During the Siamese Mission to London in 1857, Queen Victoria gifted a coin-minting machine to Siamese court, leading to establishment of minting house in royal treasury department. ฺThree British engineers arrived in Siam with the machine in 1857 but all three of them died soon from fever, drowning and cholera, leaving the machine unoperated. King Mongkut then had to assign a native Siamese nobleman named Moed () to learn operation of minting machine. First Siamese machine-minted coinage was issued in 1860. It took time for Siamese society to accept modern coin usage and traditional Photduang was used concurrently. Diplomacy Qing China Siam had entered the Chinese tributary relationship system, in which the Chinese imperial court recognized the rulers of Siam to maintain relations, since Sukhothai and Ayutthaya periods. Siamese missions to the Chinese imperial court were called Chim Kong (進貢 POJ: chìn-kòng "to offer gifts"). The Chinese Emperors conferred the Hong