36. Smegma 204 37. Diphryx _ib._ 38. Particulars relative to the Servilian triens 205 39. Iron ores _ib._ 40. Statues of iron; chased works in iron 206 41. The different kinds of iron, and the mode of tempering it _ib._ 42. The metal called live iron 209 43. Methods of preventing rust _ib._ 44. Seven remedies derived from iron 210 45. Fourteen remedies derived from rust 211 46. Seventeen remedies derived from the scales of iron. Hygremplastrum _ib._ 47. The ores of lead 212 48. Stannum. Argentarium 214 49. Black lead 215 50. Fifteen remedies derived from lead 216 51. Fifteen remedies derived from the scoria of lead 218 52. Spodium of lead _ib._ 53. Molybdæna: fifteen remedies _ib._ 54. Psimithium, or ceruse; six remedies 219 55. Sandarach: eleven remedies 220 56. Arrhenicum _ib._ BOOK XXXV. AN ACCOUNT OF PAINTINGS AND COLOURS. 1. The honour attached to painting 223 2. The honour attached to portraits 224 3. When shields were first invented with portraits upon them; and when they were first erected in public 227 4. When these shields were first placed in private houses _ib._ 5. The commencement of the art of painting. Monochrome paintings. The earliest painters 228 6. The antiquity of painting in Italy 229 7. Roman painters 230 8. At what period foreign paintings were first introduced at Rome 232 9. At what period painting was first held in high esteem at Rome, and from what causes _ib._ 10. What pictures the Emperors have exhibited in public 233 11. The art of painting 234 12. Pigments other than those of a metallic origin. Artificial colours 235 13. Sinopis: eleven remedies _ib._