168 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS might occur. H•S gas can be smelt and chemically confirmed by the browning of lead acetate/cotton plugs. Hydrochloric acid 6M. Heat a little of the ash residue (1) with « ml of the acid. Coloration might occur. NaOH 8M. Add a little of the isolated pigment to « ml of NaOH 8M. Gas evolution or coloration might occur. Aqua regia. (50•o Nitric acid •- HC1 6M, 3: 1 v/v.). A little of the isolated pigment is added to « ml of aqua regia. The pigment might dissolve and the liquid colour. Di•nethylformamide (DMF). Add a little of the isolated pigment to 1 ml of DMF. Coloration of the solvent might occur. Methanol. Add a little of the isolated pigment to 1 ml of methanol. Colora- tion of the solvent might occur. Sodium peroxide melt. Melt a small amount of the ash residue (1) with several granules of sodium peroxide in a vitreosol or quartz crucible. Observe colour after cooling. If characteristic reactions should be obtained with this melt, all of the excess sodium peroxide should first be decomposed by excessive heating. Borax bead. Melt borax powder on a platinum wire loop with a little of the ash residue (1). Observe the colour of the hot bead and after cooling. Dissolution. Heat a small amount of the ash residue (1) with a mixture of ca 0.25 g KHSO4 and ca 0.25 conc. sulphuric acid, in a small kjeldahl flask over a small flame of a microburner. Cool and dilute with water. Thin-layer chromatography. Details of tlc identification will be given under chapter 3: lipstick colours. Metal analysis. This will not be discussed in this paper. Microscope. Suspend the isolated pigment in glycerol. Observe plate structures and colour interference under the microscope. Compare with reference samples. Observations Chromium-oxides 77288 Cr•Oa 77289 2CrOa.3H•.O Ash. Both pigments turn grey during the ashing, which becomes dull-green after cooling. Sulphuric acid 4M. Chromic oxides are insoluble and remain unchanged by this reagent. NaOH 8M. Chromic oxides are insoluble and colour persists in this reagent.

RISK-BEARING SUBSTANCES IN COSMETICS 169 Iron compounds 77510 Ferric ferrocyanide 77489 Yellow-iron oxide. Ochre Fe2Oa.nH20 77491 Red iron oxide. Fe2Oa 77492 Brown iron oxide. F%Oa 77499 Black iron oxide. FeaO4 Ultramarines 77007 Ultramarine blue, violet, pink Mn-compounds 77745 Mn-phos- phate Mna(PO4h.7HaO 77742 Mn-violet Mn NH• PaO7 --Burnt Umber Mn containing iron oxide Sodium peroxide melt. The melt is yellow coloured, due to the formation of a chromate. Cool the melt and dissolve in sulphuric acid 4M, until reaction is acid. Boil the solu- tion until the excess peroxide is decomposed. Cool and add diphenylcarbazide reagent. A violet colour indicates chrome. Ash. All iron oxides turn brownblack to black during the ashing which turn deepbrown after cooling. Sulphuric acid 4M. This reagent is only of importance to distinguish Prussian blue (Ferric ferrocyanide) and Ultramarine blue. Prussian blue retains its colour, Ultra- marine fades. HCI 6M. Heat the pigments in this reagent until dis- solved. The hot solution is yellow. Dilute with 5 x its volume with water. The yellow colour fades. Add several crystals of K-ferro cyanide. A blue precipitate indicates iron. NaOH 8M. As reaction no 2, this reaction will distin- guish Prussian blue and Ultramarine blue. Prussian blue turns redbrown, but Ultramarine retains its blue colour. Ash. All Ultramarines turn grey during the ashing, which turns blue after cooling. Sulphuric acid 4M. All Ultramarines decompose with dilute acid even without heating. The residue is white. HaS gas evolution occurs, which can be smelled and character- ized by the browning of lead acetate/cotton plugs. NaOH. Ultramarines retain their colour in this reagent, in contrast to Prussian blue (see under Fe-compounds). Ash. Both violet Mn phosphates turn white after the ashing. Burnt umber however retains its colour. Sulphuric acid 4M. This reaction confirms the phos- phate. Mix the ash residue with this reagent. Add Amm. molybdate reagent. Heat. A yellow colour indicates phos- phate. NaOH 8M. This reaction confirms the NH• radical. Mix with the reagent. Heat gently. NHa gas will escape, which can be shown by the yellow-brown coloration of a hanging drop Nessler reagent. Sodium peroxide melt. The reaction is only of im- portance of the violet Mn-compounds. The melt is green