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

170 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS coloured, due to the formed manganate. Destroy excess peroxide by heating. Cool. Dissolve melt in 2 ml water. The colour is still green. Acidify. The colour turns into violet, caused by permanganate. Metal analysis. if burnt umber is confirmed, metal analysis should be made. The ratio Fe/Mn might give an indication of the umber origin. Co-compounds 77346 Cobalt aluminate. CoO.A1203 Ash. Cobalt aluminate is the only eye make-up colour that retains its beautiful blue colour during and after the ashing. Borax bead. The colour of the borax bead is deep blue. Carbon 77266 Carbon black 77267 Bone black --Vegetable black Organic colours 75470 Carmine. A1/Ca lake of carminic acid 75810 Cu-chloro- phyllene There are many synthetic organic colours possible. Pearl-pigments 77000 Aluminum powder 77400 Copper/ bronze powder Ash. The residue after ashing is of importance. Carbon black has no residue Bone black leaves 80•o of white residue. Vegetable black leaves a much smaller amount of residue. $ulphuric acid 4M. This reagent is only of importance to confirm the ash residue of bone black, which contain phosphates. A small amount of the ash residue is heated with « ml sulphuric acid 4M and NH4 molybdate reagent. The phosphates give a yellow coloration. $ulphuric acid 4M. Colouring of the dilute acid after heating might show the presence of an organic colour. Dimethylformamide. Colouring of this solvent by a small amount of the isolated pigment might show the presence of an organic colour. Filter. Concentrate by evaporation (in the hood !) on a waterbath and use the solution for tlc. N.B. Many lakes are appreciably soluble in dimethylformamide. Methanol. This solvent will dissolve the unsulphonated organic colours, leaving the lakes undissolved. Concen- trate the solution and proceed with tlc for identification. Thin-layer chromatography. Use the extract of 6 and 7 for tlc using the systems of chapter 3: identification of lipstick colours. Ash. Aluminum powder burns with flashes, leaving a white oxide. If there is a strong orange colour, BiOC1 might be present. This compound turns white again after heating for a short time, but if heating is excessive the colour remains yellow after ashing. TiOa and ZnO turns