STUDIES ON THE PERMEABILITY OF THE SKIN TO MERCURY 80 firm this, four different mercurials, ammoniated mercury, metallic mer- cury, yellow oxide of mercury, and calomel were suspended, re- spectively, in each of two double component bases consisting of equal parts of lard and lanolin and equal parts of petrolatum and lanolin. These vehicles were selected for st. ud.y because they frequently form the main base for a number of com- monly used ointments. The' con- centration of mercury was 25 per cent in all cases. In Table 9 is shown ammoniated mercury, while of little or no significance in vehicle E, is highly significant in vehicle A. Pre- sumably this marked effect of the 'vehicle may be attributed to some interaction with the compound, as has been suggested by Moncorps (8) who observed that the stability of ammoniated nlercury was some- what uncertain. It is, therefore, not unlikely that the reactivity of a compound with its vehicle may be one of the causes of differences be- tween compounds. TABLE 9--COMPARISON BETWEEN Two TYPES OF VEHICLES CONSISTINO 'OF LARD AND PETKO- LATUM WITH nANOLIN AS COMMON CONSTITUENT ON THE PENETRATION OF FOUR DIFFERENT MERCUP4ALS The concentration of mercury in all ointments is 25 per cent. The measure of penetration is' the storage of mercury in the kidneys of the rat Vehicle Calomel Micrograms Mercury per Gram Wet Kidney Ammoniated Metallic Yellow Oxide Mercury Mercury Mercury E 50% Petrolatum). 50% Lanolin f 4.2 5.5 ' 7.9 11 A 50% Lard } . 50% Lanolin f 8.8 19 14 23 The results are averages of six animals on each treatment. the marked superiority of the lard- component vehicle over the petro- latum-component vehicle. The in- crease in penetration of mercury from calomel, metallic and yellow oxide is roughly twofold, but in the case of the ammoniated mercury the increase is nearly fourfold. Be•ides the profound difference in penetra- tion of mercury, which can be at- tributed directly to the influence of the vehicle, it must be emphasized that the compound of mercury also has an effect on penetration, yellow oxide giving the highest and calomel the lowest. It is to be noted that the difference between calomel and Effect of PFetting /lgents Numerous observations have indi- cated that the presence of wetting agents might be very important to the penetration of substances through the skin. In order to study the effect of wetting agents on mer- cury penetration, two factors were considered: (1) type of wetting agent, (2) type of vehicle. For the first experiment a well-known aryl alkyl polyether alcohol (Triton NE) was mixed in 2 per cent concentra- tion in three different bases, repre- sentative of (A) a pure animal fat, (B) a pure mineral base, (C) an oil-

90 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS in-water emulsion type, the latter being chosen because its properties might be expected to be most modi- fied by the presence of a wetting agent. The results. are given in Table 10. There was no effect on B, the vehicle whieh contained no water. In the case of vehicles A and C, marked incr4ase of mercury pene- tration was brought about by. the wetting agent. The effect of tile wett?ng agent on C is p6rhaps to be expected but on A more difficult to interpret because, Jike B, the vehicle contained no water. With the indication that in cer- tain bases, Triton NE enhances the penetration of mercury, it seemed of interest to determine whether differences between wetting agents could be demonstrated. The effect of 2 per cent concentration of Triton NE, Aerosol OT (sodium dioctyl sulfosuccihate) and Duponal C (sodium lauryl sulfate) in base A was studied. No differences in cutaneous penetration of mer- cury were found. Whether this would hold for the oil-in-water base or certainother types refnains at pres- ß ent undetermined. The most that can be said for the tests with wetting agents is that the degree of increased pendtration of mercury is .disap- pointingly small as compared with that observed by Dueruling (9). z•. Effect of Stiffening of/he l/ehicle Many of the ointments submitted for assay were rather stiff and did not spread easily. It was noted that this characteristic seemed to