PAINTS, DYES, AND VARNISHES 



ent of the most brilliant of the mineral red pigments, 

 vermilion. Indeed, it is an unfortunate fact that most 

 of the permanent mineral pigments the green of ar- 

 senic, the blue of the prussic-acid compounds, as well 

 as the compounds of lead and mercury, are poisonous. 



Chemically, vermilion is a mercuric sulphide, having 

 the formula HgS. It is found in nature as cinnabar, 

 and the selected pieces of this mineral are placed on the 

 market as "mountain vermilion." This is usually an 

 inferior pigment, however, most of the vermilion on the 

 market being an artificial product. 



There are two forms of the mercuric sulphide, a 

 non-crystalline one, black in color, and the one of crys- 

 talline form, known as vermilion. Either one of these 

 may be produced from the other by proper manipula- 

 tion; and in practice the red sulphide is frequently 

 made from the black. 



Black sulphide may be made by the simple processes 

 of stirring together equal parts of mercury and sulphur 

 moistened with water, a mixture of mercury and 

 ammonium sulphide, or by heating mercury and sul- 

 phur together. It is a velvety, black mass, which is 

 changed into the crystalline sulphide, or vermilion, by 

 heating to a temperature at which it volatilizes. 



Chinese vermilion, which is superior in quality and 

 shade to Western vermilions, is a mercury product pre- 

 pared by some process unknown to Europeans. The 

 alleged method of making it has been told many times, 

 but the true method probably still remains a secret of 

 the Orientals. It is a very expensive pigment; but so 

 also are the Western vermilions, even the cheapest of 

 VOL. vra. 19 [ 289 ] 



