GOVERNMENT REPORT 155 GOVERNMENT REPORT. Report to the Local Government Board on Analyses and Methods of Detection of Certain Proprietary Substances sold as Preservatives for Milk, Cream, etc. G. Monier-Williams. (Food Reports, 1912, No. 17, 1-7.)-A new preservative, sold under the name of (‘ mystin,” for preserving milk and cream, has recently been advertised as possessing the advantage that its presence cannot be detected by analysis. An analysis of the preparation showed that it had the following composition : Sodium nitrate, 9.85 ; formaldehyde, 0.30 ; water, 89.85 per cent.; the smell of the preparation indicated the presence of some essential oil, probably peppermint oil. The directions given prescribe the addition of 3 ounces of the preparation to 17 imperial gallons of milk.I t was found that milk treated with this proportion of ( ( mystin ” failed to give the Hehner reaction for formaldehyde. This action of the nitrite in inhibiting the reaction appears to be due to the action of the nitrous acid with the tryptophane which is present among the products of hydro- lysis of casein, rendering the tryptophane incapable of condensing with formaldehyde. Xf, however, the nitrous acid in the acidified milk be destroyed by some such substance as urea, the milk treated with c 6 mystin ” readily yields a coloration with Hehner’s test. Five C.C. of the milk should be treated with 0.05 grm. of urea and 1 C.C. of sulphuric acid, the mixture heated for two minutes in a boiling water-bath, then cooled, and tested in the usual may. The quantity of formaldehyde may be.estimated by the method described by Shrewsbury and Knapp (ANALYST, 1909,. 34, 12), after the milk has been treated with urea. In view of the possibility that ‘‘ mystin ” may have already come into extensive use among milk vendors, it would appear to be advisable to include the Griess-Ilosvay test for nitrites among the routine tests applied to milk and cream samples ; milk containing mystin ” gives a pink coloration almost immediately with this test, and if a positive reaction is obtained, formaldehyde should be looked for by the method given above. It is pointed out that a quart of milk (treated with the proportion of “ mystin ” directed) would contain 2 grains of sodium nitrite, which is the maximum pharmacopoeia1 dose of this salt.Sodium nitrite is a dangerous drug, with a powerful action on the heart, and the risk of using any preparation containing a comparatively large amount of sodium nitrite is universally recognised. Reference is made to certain other preservatives for milk, cream, and margarine, to which the attention of the Board has recently been drawn. One of these, sold under the name of (( accoine,” consisted of an aqueous solution containing 13-97 per cent. of sodium benzoate, and 1.94 per cent. of sodium carbonate. I t is claimed also for this preparation that it cannot be detected by analysis, but the presence of156 REVIEWS benzoic acid in milk and cream may be detected by the test described by Richmond (ANALYST, 1907, 32, 151). Another substance, sold as a preservative for margarine, was found to consist almost entirely of sodium fluoride, whilst a, cream preservative examined consisted of a mixture of sodium meta-bisulphite and sodium sulphate. w. P. s.