4 New Frocefsfor mahin^ Attific'tal Clnnnhar In 



praftice the manufadurer will foon difcover the neceflary proportions and manipulationsr 

 I therefore claim and hope for the grant of indulgence in favour of the defire I have, that 

 the valuable difcovery of KirchofF may fpeedily become as ufeful to fociety as undoubtedly 

 it will fooner or later be. 



The firft experiment I made in fmall, according to the exa£l proportions of KirchofF, 

 ^id not fucceed. I could not transform my ethiops into cinnabar. I attribute this want 

 of fuccefs to an evaporation too rapid, and the want of a fuflicient quantity of fluid ; not 

 having added water in proportion as the mixture became thick, fo that the whole foon be- 

 came perfe£lly dry. The mafs became ftrongly attached to the china cup, and con- 

 ftantly preferved its black colour. I recommenced the operation with more fuccefs, and 

 all my experiments afforded cinnabar more or lefs beautiful, provided the mixture at the 

 commencement was kept at the proper degree of fluidity. Moft frequently however I 

 obtained a colour, which, though very brilliant, inclined rather to yellow than red; a fault 

 which the cinnabar of fublimation poffeffes but too frequently, and is fometimes a proof 

 of its falfification. Among the colours which I obtained, brown prefented itfelfbuttoo 

 frequently, in confequence of having negledled the moment of terminating the operation. 

 I made the following experiments on thefe defeftivc colours : 



After well edulcorating a cinnabar of this kind, I poured on three different portions : the 

 nitrous, the acetous, and the muriatic acids. Thefe were expofed for feveral hours to a 

 mild digefling heat. I had fuppofed that the defeft of the colour might arife either from 

 a partial redu£lion of the mercury, or partial fufion of the fulphur, or perhaps from an 

 adulteration of the mercury by lead. In thefe three experiments, therefore, my aim was to 

 diffolve the reduced mercury, to oxide the fulphur, or to carry off the lead by the acetic acid. 

 None of thefe experiments ahfwered my expectation ; for, though part of the mercury 

 was diffolved and part of the fulphur oxided, the colour continued brown. That with the 

 nitrous acid was even darker. The acetic acid afforded no indications of lead. 



As the refult of thefe experiments Ihowed that the bad colour of the cinnabar did not 

 arife from a portion of reduced mercury, I wilhed to know whether the metal were not 

 combined with too large a portion of fulphur; for which purpofe, I digefted cauftic al- 

 kali on the cinnabar. The alkaline folution became yellowifli, and the colour of the cin- 

 nabar fomewhat lighter, but was not a good red. It always inclined to yellow ; and though 

 it approached very near the colour of common cinnabar, and was even more vivid, yet it 

 was not red enough. 



I had little cxpeftation of reftoring the proper colour and vividnefs to my damaged cin- 

 nabar. Nothing more remained but to try the addition of mercury to the brown colour 

 which was the objeft of my refearch. I therefore moiftened near an ounce and a half of 

 this colour with water, then gradually added near three ounces of running mercury, and 

 triturated the whole on a very hard Siberian porphyry. Contrary to my expe6lation, the 

 mafs, inflead of becoming black, affumed the colour of an extremely pale cinnabar, with- 

 out the fmalleft degree of fire or livelinefs. I then mixed two drams of the flowers of 

 fulphur, and colle£ted the whole in a porcelaine cup. Upon this I poured a folution of the 

 cauftic alkali, evaporated as before to a very thick confiftence. The mixture paffed from 

 yellow to an obfcure brown, and at the moment of the thickening a large quantity of 

 running mercury was feen at the bottom of the cup. I added a dram and a half of 



fulphur. 



