2. Surface-layer Enrichment by Addition

Mercury amalgams were used for plating the metalsurfaces, i.e., gilding or silvering, before the invention of electroplating. Molten amalgam of gold and mercury (or silver and mercury) is smeared on the cleansed metal surface. On heating, mercury gets volatilised and a thin layer of gold or silver is obtained on the surface of the metal. The descriptions of this kind of amalgamation gilding are found in Slokas 150, 720, 600-602. 21 One masa ball of mercury (mrtgolaka) and one masa ball of killed gold are to be rubbed, with citric acid for three days. The leaves of one "karsa" of lead, smeared with this paste of gold and mercury kept in a closed crucible when roasted becomes gold. It (gold) is to be taken out when it cools down by itself. The gold thus produced, is to be collected to attain success in the pursuit of Dharma, Artha, and Kama. 21. ' Rasarnavakalpa, Sloka 149-151, p. 18. mrtagolakamasaika masaika hemagolakam || 149 || ekikrtya tu samartha lun ‌gamlena dinatrayam | karsom ke nagapatrani rasakallena lepayet 11 150 11 jayate kanakam divyamandhamusapudhe krte | svan ‌gasitanca samgrahyam dharmakamartha siddhidam || 151 || 81

22 Gold, mica, mercury, powder of kanta (magnetic oxide of iron) and moon-water, mi xed well and roasted over fire, makes mercury attain the stage of "khota" fixation. By the "touch" of this mercury all metals are transmuted. Metals, when treated with this mercury and roasted in fire becomes gold. 23 Mercury, gold pyrites, Vimala (silver pyrites with golden tints), realgar, sulphur, cinnabar and amalgam of gold and mica are to be mixed thoroughly with the juice of Rudanti (Cressa Cretica) for seven days. This is to be smeared on silver foils which on roasting them over fire of cow dung and dipping, in the juice of this plant becomes gold of beautiful lustre. 22. 23. 1 Rasarnavakalpa, Sloka 719 - 720, p. 55. kancanam gaganam sutam kantacurnanca tanjalam 1 madeyitva dharmadagnau khotabaddhah prajayata || 919 || tasya ca sparsamatrena sarvalohani vidhyati | agnimadhye dharmacannu jayate kancanam subham Rasarnavakalpa, Sloka 600- 603, p. 49. 1172011 rasanca manikancaiva vimala ca manahsila | andhaka daradancaiva hemabhraka samanvitam || 600 ruda-nirasatah sarvam mardayetsaptavasaran | nenaiva narapatrani liptva putena pacayen || 6 || tahase dhala ye caiva hemam bhavati sobhanam | sada ‌nti patra niryasa hemaika visobhanam || 602 || 82