DETECTION OF P-NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS 34 1 PROCEEDINGS OF THE SOCIETY OF PUBLIC ANALYSTS AND OTHER ANALYTICAL CHEMISTS. NOTE ON THE DETECTION OF P-NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS. BY R. BODMER, F.I.C. (Read at the Meeting, June 2, 1915.) EAVING recently been engaged in the analysis of British-made lysol and similar preparations, the question arose as to whether P-naphthol had been used to bring up the Rideal-Walker coefhient, I endeavoured, without success, to effect a separa- tion of P-naphthol from cresol, and, failing this, I tried direct tests.Richmond and Miller (ANALYST, 1907, 32, 151) describe three tests for the detection of P-naphthol in milk. One of these, involving the use of a diazotised benzidine chloride solution, answers quite well.The method I adopted was as follows: One C.C. of the suspected lysol wa,~ dissolved in distilled water and made up to 100 C.C. (Lysol should give a perfectly clear solution with distilled water in all proportions.) Side by side with this a solution of lysol free from P-naphthol was made of the same strength. On adding about 1 C.C. of the benzidine reagent the pure lysol gives an orange-coloured solution, but if as little as 0.2 per cent.of P-naphthol is present, a fine red colour is developed. Care must be taken to compare solutions of bhe same strength, so that an approximate knowledge of the proportion of cresol in each is necessary, If the solution of cresol is too strong, a reddish orange colour is produced. I have tried a diazotised solution of phenylhydrazine, but the difference in colour between the pure lysol solution and that containing P-naphthol is not so rn arked .J. Katsyama and B. Ikada (ANALYST, 1915, 164) describe a test for P-naphthol. When a few drops of strong sulphuric acid are added to a weak solution of /3-naphthol (the solvent used is not stated), and then a few drops of very weak sodium nitrite added, when a purple colour is developed.This test is not a good one, as on adding sulphuric acid to the solution of the distillate from the lysol in dilute soda the cresol and @-naphthol are thrown out and the nitrite fails to react. Another test recommended by Richmond for milk is to extract with Chloroform and heat the chloroform solution with sodium hydroxide. This is quite useless, as the chloroform dissolves the cresol as well as the /3-naphthol, By testing the lysol solution in the way I have indicated, and comparing the depth of tint with that given by s solution of lysol containing a known amount of342 DETECTION OF ,%NAPHTHOL IN LYSOL AND SIMILAR PREPARATIONS &naphthol, an approximate idea is obtained of the proportion of the latter present.I have proved by experiment, making up lysol with 50 per cent. cresol and 50 per cent. soft soap, that the presence of the soap does not interfere with the red colour produced by the benzidine reagent. The benzidine reagent is made up as follows : One grm. benzidine, 4 C.C. strong hydrochloric acid, and 1 grm. sodium nitrite, are made up to 100 C.C. with water and neutralised.The reagent does not keep well. DISCUSSION. Dr. RIDEAL said that any method capable of determining the presence of other bodies than cresols in lysol would be helpful. Is seemed, however, as was often the case with proprietary articles, lysol had so many rivals and substitutes producing similar results that at the present time the name had ceased to have any definite meaning, and might well be discontinued.I t would be far better to describe the disinfectant in terms of its disinfecting properties, as expressed by the Rideal-Walker coefficient or some other bacterial test. Mr. J. L. BAKER said that he should have thought that the presence of P-naphthol was rather an advantage than otherwise. Mr. W. PARTRIDUE said that one of the advantages of lysol, possessed by few other disinfectants, was that it yielded a clear, or nearly clear, solution.Although poisonous, it was useful for laboratory purposes, being, for instance, an efficient cleaning agent for microscope slides. Dr. RIDEAL remarked that he believed that a War Office preparation was required under the name of liquor cresoli saponatus fortis,” having a, coefficient of over 10 by the Rideal-Walker test, which must contain other bodies than cresols.The PRESIDENT said that it seemed to him that it could not be regarded as objectionable to increase the killing power of a disinfectant, and he did not think Mr. Bodmer suggested that it was; but in any case thanks were due to Mr. Bodmer for his description of a new method for the detection and approximate estimation of /%naphthol.Mr. BODMER, in reply, said that extravagant claims were made for some of these preparations, One, which was not sold as lysol and did not give a clear solution, was stated to have a Rideal-Walker coefficient of 26, whereas that of cresylic acid was only about 3. He had not been able to find any very definite statement as to the coefficient of ,@-naphthol, but as far as he could make out it was said to be about 11, and it was difficult to imagine that by the addition of a small proportion of such a substance the coefficient of cresol would be increased to 26.He had not expected the method to be quantitative, but within certain limits the differences in colour with different quantities of ,@-naphthol were marked, and by working carefully one could readily distinguish between 0.2, 0.5, and 1 per cent. It was not possible to separate the ,@-naphthol by fractional distillation, since a certain amount of cresylic acid came over even at the end j but if, after fractional distillation, the last runnings were dissolved in soda and the benzidine reagent added, theSEIICHI UENO : COREAN BEESWAX 343 reaction was sharper and more marked than in the original, enabling small quantities to be more easily detected. So far he had not detected @-naphthol in lysol sob7 as such, but in another preparation-the one referred to above-stated to have a, coefficient of 26.