JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS the chips, to give ease in plodding and facilitate stamping-out-of the final soap tablet. The presence of any excess, how- ever slight, of alkali in the base, often causes perfumery difficulties, as alkalis saponify any esters used in the perfume compound. In the higher priced range of toilet. soaps, the use of cinnamic acid is a most satisfactory addition, for this acid acts as a neutraliser, antioxidant and fixative. To enumerate the various possibili- ties of deterioration caused by the use of perfume compounds is beyond the scope of this paper, as among the aromatic constituents used one can have both positive and negative catalysts present, aromatic alcohols and the esters thereof, certain ketonic bodies such as musk ketone then synthetics as, for example, ber/zaldehyde and in the formula- tion of a soap perfume the reactions of all ingredients must .be very carefully considered before use, with price considerations put entirely at one side until a satisfactory com- pound has been obtained. Then a cost adjustment may be made and by careful substitution of analogous replacement materials the desired cost price may be approached. I would once again emphasise, how- ever, that it is not always economical to employ cheaper products. Metallic contamination is the final cause of deterioration and, in particu- lar, contamination caused by copper base dies that are in poor condition either through neglect or wear and tear. All machines should be regu- 230 larly maintained and any signs of plate stripping be returned for replating, as only in this way can a perfect product be assured. The superfarting of toilet sokps is a well-known practice to-day,: whether milled or cold-processed soaps are being considered, and many combinations are possible. Lanolin, of course, was once the most favoured superfatting agent, but owing to" odour difficultie, s it has been replaced by various other ingredients. Prob-:!! ably one of the best is the use of emulsion compound of Polyethylene' ::!:i Glycol 1500, 'Mineral Oil (in traces), Wool Wax Alcohols, Oleyl .:: and Cetyl Alcohol. An even more:?• modern method is the use of phonated Cetyl/Oleyl Alcohols impart a remarkable smoothness t6 the soap base. ß COLORATION _AND DI The final subject in this br[• collection of notes must be : coloration of soaps, a matter:i great importance, as even the slighi I est discoloration in a white soap mar the product. Pastel shades popular and can suitably cover an, mild discolorations due to either soap base or the perfumery corn pound. It is the latter, when doubtful nature, that causes deterioration of a soap, as:ifil ß "faults" only develop upon agei• and are most unsightly either throUg spotting or just partial solid aromatic body should ever}:ii I• employed unless the whole of•:i i• crystalline derivatives have ei• been dissolved along with the no•

SOME CURRENT PROBLEMS IN blend or in a suitable solvent as benzyl alcohol. for colouring matter, only a fast-to-alkali colour mid be employed. Again, it is economy to purchase anything the finest quality, as'the cheaper may contain many impurities in the more expensive variety, been eliminated by sufficient Aniline dyestuffs are chiefly although only those with alkaline milling resistance and uate manufacturers' proof of should be used. A simple yet a most reliable one, is to 50 grammes of the soap base' 5 grammes of soda ash to a litre distilled water and gently heat maintain at a temperature of C. until observations are corn- The soap base employed course, have been already TOILET SOAP MANUFACTURE coloured, then as "fastness" is usually based upon an "8" scale, any soap can be calculated as to the degree of fastness to alkali. Then if the degree of the dyestuft itself is known (and it should be requested -from the makers), on'e aims at employing an alkaline fastness from 4 to 5 or even higher. The test given will soon reveal whether the soap will remain constant or not, during the normally expected shelf-life of the final product. The dyestuff used, and of whatever nature, must also, of course, be employed in a solution form that has been filtered so that no extrane- ous matter or fine particles of dye- stuff are left for subsequent incor- poration in the soap base, a fault that usually gives rise, within a few weeks or months, to more or less clearly defined spotting.