Chapter 12

--_Amer. Chem. Jour._

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DETECTION OF PEANUT OIL IN OLIVE OIL.

Holde, after a careful trial of the various processes for detecting the above adulteration, gives the preference to Renard's, which he describes as follows:

Ten grms. of the suspected oil, after being saponified, and the fatty acids separated by hydrochloric acid, are dissolved in 90 per cent. alcohol, and precipitated by sugar of lead. The oleate of lead is separated by ether, and the residuum, consisting of palmitic and arachic acids, is decomposed by hydrochloric acid. The fatty acids are dissolved, with the aid of heat, in 50 c.c. of 90 per cent. alcohol. The arachic acid which separates after cooling is filtered out and washed, first with 90 per cent. and afterward with 70 per cent. alcohol. It is then dissolved in hot alcohol, and the solution evaporated in a weighed saucer. The weight of the residuum, after taking into account the acid dissolved in the alcohol, equals the whole amount of arachic acid contained in the oil; the melting point of this residuum should be 70° to 71° C. With this process the author has always been successful; but when the olive oil contains not more than 5 to 10 per cent. of peanut oil, it is necessary to make the test with 40 grms. of the former, otherwise the melting point of the arachic acid cannot be estimated. Furthermore, the acids which are separated from the lead salt by hydrochloric acid must be recrystallized repeatedly with 90 per cent. alcohol, until the melting point ceases to rise, in case the latter is not found to exceed 70° C. at the first estimation. When peanut oil is present, the melting point will always be above 70°.--_Chem. Zeit._

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HYDROXYLAMINE.

Free hydroxylamine, NH_{2}OH, has been isolated by M. Lobry de Bruyn, and a preliminary account of its mode of preparation and properties is published by him in the current number of the _Recueil des travaux chimiques des Pays-Bas_ (1891, 10, 101). The manner in which the free base was obtained was briefly as follows. About a hundred grammes of hydroxylamine hydrochloride, NH_{2}OH.HCl, were dissolved in six hundred cubic centimeters of warm methyl alcohol. To this solution a quantity of sodium dissolved in methyl alcohol was added, in such proportion that the hydrochloride of hydroxylamine was present in slight excess over and above that required to convert it to sodium chloride. After deposition of the separated sodium chloride the solution was decanted and filtered.

The greater portion of the methyl alcohol was next removed by distillation under the reduced pressure of 160-200 mm. The remainder was then treated with anhydrous ether, in order to completely precipitate the last traces of dissolved sodium chloride. The liquid eventually separated into two layers, an upper ethereal layer containing about 5 per cent. of hydroxylamine, and a lower layer containing over 50 per cent. of hydroxylamine, the remainder of the methyl alcohol, and a little dissolved salt. By subjecting this lower layer to fractional distillation under 60 mm. pressure, it was separated into three fractions, of which the first contained 27 per cent. of hydroxylamine, the second 60 per cent., and the third crystallized in the ice-cooled receiver in long needles. This third fraction consisted of free solid NH_{2}OH. Hydroxylamine as thus isolated in the free state is a very hygroscopic substance, which rapidly liquefies when exposed to air, owing to the absorption of water.

The crystals melt at 33°, and the fused substance appears to possess the capability of readily dissolving metallic salts. Sodium chloride is very largely soluble in the liquid; powdered niter melts at once in contact with it, and the two liquids then mix. Free hydroxylamine is without odor. It is heavier than water. When rapidly heated upon platinum foil it suddenly decomposes in a most violent manner, with production of a large sheet of bright yellow flame. It is only very slightly soluble in liquid carbon compounds, such as chloroform, benzene, ether, acetic ether, and carbon bisulphide. The vapor attacks corks, so that the solid requires to be preserved in glass-stoppered bottles. The free base appears also to act upon cellulose, for, upon placing a few drops of the melted substance upon filter paper, a considerable amount of heat is evolved. The pure crystals are very stable, the base in the free state appearing to possess much greater stability than when dissolved in water. The instability of the solution appears, however, to be influenced to a considerable extent by the alkalinity of the glass of the containing vessel, for concentrated solutions free from dissolved alkali are found to be perfectly stable. Bromine and iodine react in a remarkable manner with free hydroxylamine.

Crystals of iodine dissolve instantly in contact with it, with evolution of a gas and considerable rise of temperature. Bromine reacts with violence, a gas again being explosively evolved and hydrobromic acid formed. The nature of the gas evolved is now undergoing investigation. A letter from M. Lobry de Bruyn appears in the number of the _Chemiker Zeitung_ for October 31, warning those who may attempt to prepare free hydroxylamine by the above method that it is a dangerously explosive substance when warmed to a temperature of 80°-100°. Upon warming a flask containing the free solid base upon a water bath a most violent explosion occurs. A spontaneous decomposition appears to set in about 80°, and even in open vessels the explosion is very violent. Care must also be taken during the fractional distillation of the concentrated solution in methyl alcohol to cool the apparatus before changing the receiver, as if air is admitted while the retort is heated the experiment ends with an explosion.--_Nature_.

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