THE ANALYST. 199 INORGANIC ANALYSIS. L. Dbbourdeaux. ( A m . cle Chhi. unal., 1904, ix,, 121-123.)-The determination of the amount of chlorine that can be liberated by oxides of manganese, and of the amount of hydrochloric acid required to liberate the chlorine, can be effected in one operation, which is as accurate as and much more convenient than the ordinary methods employed. I t is based on the destruction of oxalic acid by the manganese oxides in the presence of dilute sul- phuric acid. VuliictlioiL of Oxides of Manganese.-The following equations represent the reactions that take place in the industrial manufacture of chlorine, and in the author’s new method : Mn02 + 4HC1= MnCl, + CI, + H20. Mn,O, + 6HC1= 2MnC1, + C1, + H,O. Mn,O, + 8HC1= 3MnC1, + C1, + H,O. The Valuation of Oxides of Manganese.MnO, + &C20,.2H20 + H,SO, = MUSO, + 2C0, + 4H2O. Mn,O, + H2C20,.2H20 + 2H,SO, = 2MnS0, + 2C0, + 5H20. Mn,O, + H,C20,.2H,0 + 3H,SO, = 3MnS0, + 2C0, + 6H,O. Hence, each molecule of oxalic acid corresponds to a molecule of chlorine liberated. In making an estimation, from 0.75 to 1 gramme of the sample is placed in a small flask with 50 C.C. of a solution containing 35 to 40 grammes of crystallized oxalic acid, and 120 C.C. of sulphuric acid-specific gravity 1*82-(6S0 Be.) in a litre of water. The flask is connected with a reflux condenser, and gently heated over a small Bunsen flame until all the oxide has dissolved, this requiring about forty- five minutes. The clear solution is then diluted to 200 c.c., and 150 C.C. titrated Kith standard potassium permanganate solution containing about 15 grammes per litre.A parallel determination is made by diluting 50 C.C. of the oxalic acid solution to 200 c.c., and titrating 150 c.c., and from the difference between the results of the titrations the amount of oxalic acid destroyed and the corresponding amount of chlorine can be calculated. Detewuiiration of the L4itwtuzt of Hydrochloric Acid Required.-According to the above equations the amount of hydrochloric acid used in the preparation of chlorine corresponds with the sum of the sulphuric acid saturated and oxalic acid destroyed. Thus, if the residual 50 C.C. of each of the diluted liquids (used for the permanganate titration) be titrated with a standard solution of ammonia, with fluorescein as indicator, the difference between the two results will furnish a, measure of the200 quantity of hydrochloric acid required.The accuracy of this method is shown by the results of test experiments. This method might also be adapted to the valuation of the higher oxides of lead. C. A. M. On a Reaction of Lanthanum Salts. N. A. Orlow. (Farmaz. Jwrn., 1903, xlii., 1737 ; through Chem. Xeit. Rep., xxxiii., 36.)-Attention is called to the well- known action of iodine on lanthanum hydroxide, and especially on the basic salt produced by the action of ammonia on lanthanum aoetate, by which a blue colour is produced. A. G. L. Colour Reactions of Molybdic Acid. E. Poeei-Escot. (Ann. dt? Chim. anal., 1904, ix., 90-92.)---A solution of molybdic acid, or of a molybdate, gives an orange or reddish-orange colour with a solution of tannin, and by means of this reaction it is possible to detect 1 part of molybdic acid in 100,000.The solution should prefer- ably be neutral, since an excess of acid diminishes the sensitiveness of the re- action, or prevents it altogether in very dilute solutions. Resorcin, hydroquinone, guaiacol, and phloroglucinol do not give any coloration with molybdic acid ; but gallic acid and pyrogallol give similar colorations to that of tannin. In each case the colour is not modified by boiling the solution. Iron does not interfere with the reaction unless the quantity of tannin is sufficient to form the molybdo-tannate. The intensity of the colour is not proportional to the amount of molybdic acid, so that the reaction cannot be used for a colorimetric determination.Tungstic acid also gives a yellow coloration with tannin, but the reaction ie much less sensitive than in the case of molybdic acid. I t is also easy to distinguish between the two acids by the fact that tungstic acid gives a reddish-black coloration with hEmatein, whereas molybdic acid gives a precipitate. C. A. M. Determination of Boric Acid as Boryl Phosphate. F., Mylius and A. Meusser. (BeT., 1904, xxxvii., 397; through Chem. Zeit. Rep., 1904, xxviii., 78.)- Boric acid when treated with phosphoric acid yields a white, insoluble compound, which is not decomposed by heat. I t has the formula BPO,(probably po,,/O). BO\ In the determination of boric acid in foods, etc., the dilute alcoholic distillate obtained as usual is treated with an excess of ammonia, to decompose boric esters, before adding the phosphoric acid and proceeding with the evaporation.The residue obtained is heated for one hour at a temperature of 400' C. in a current of steam, and then weighed as BPO,. The method is suitable for determining boric acid in both organic and inorganic substances. w. P. s. Estimation of Hydrogen Peroxide i n the Presence of Potassium Persulphate by means of Potassium Permangsnate. John Albert Newton Friend. (Proc. Chem SOL, xx., 65.)-The author finds that hydrogen peroxide can be correctlyTHE ANALYST. 201 determined by means of permanganate, in the presence of potassium persulphate, only when the time of titration is short and the volume titrated small, whilst the concentration of the ealphuric acid added is fairly great.A. G. L. A New Reaction of Hydroxylamine. L. J. Simon. (Comp. rend., CXXXVii., 986 ; through Fham2. J011r92., 1904, lxxii., 247.)-When a dilute solution of m y salt of hydroxylamine is treated with a few drops of a dilute solution of sodium nitro- prusside and a slight excess of alkali, and the mixture is boiled, the original yellow c o h r of the solution becomes orange-red, changing to deep cherry-red. Nitrogen and nitrous oxide are evolved during the heating. The colour produced by a 1 in 1,000 solution of hydroxylamine hydrochloride may be again diluted to 1 in 1,000, a d is still distinct. Aldehydic and ketonic oximes, and the oximes of various glucoses, do not give the reaction. w. P. s. On the Cause of Manganese Deposits from Well-Waters. C.A. Neufeld. (.&it. fiir UTitersnch. der Nahr. m d GePiiissmittel, 1904, vii., 478, 479.)-The author draws attention to the frequent occurrence of deposits from manganiferons waters, and considers that this is due to the presence of C'reuothria: ?uaitganifera in the water, and probably not to Creizothris polyspora, as stated by other observers. I n one instance mentioned, the water passed through iron mains, and then through lead supply-pipes. The iron mains were found to be coated on their interior with a deposit 10 to 12 millimetres thick, and containing 69 per cent. of iron oxide. The lead pipes were similarly encrusted, but in this case the deposit contained 48.7 per cent. of manganese sesquioxide, with but little iron oxide.It has been noticed that only deep well-waters give this deposit. w. P. s. On the Quantitative Determination of Potassium in Mineral Waters. N. A. Orlow. (FW~UUZ. Joiim., 1903, xlii., 1737; through Chem. Zeit. Rep., xxviii., 36.)-The method is a modification of the colorimetric one of Lucian A. Hill, and depends on the colour produced by the action of potassium iodide on the aqueous solution of the potassium platinochloride after acidulation with a few drops of hydro- chloric acid. As a standard, a solution containing 0.518 gramme K,PtCI, (equivalent to 0.001 gramme K,O) in 100 C.C. of water is used. A. G. L. '1he Direct Estimation of Free Carbonic Acid in Natural Waters. A McGill. (Journ. dmer. Chem. SOC., xxvi., 183.)-The free carbonic acid is deter- mined at the source of the water, about 500 C.C. being generally used.The gas is liberated, as in Drown's method (ANALYST, xxviii., 323)) by forcing air, freed from carbon dioxide by previous passage through a soda-lime tube, through the water at the rate of about five bubbles per second. The expelled carbon dioxide is absorbed in bottles containing T& barium hydroxide solution coloured with phenolphthalein, the number of bottles needed to absorb the gas completely being a measure of its amount. Each202 THE ANALYST. bottle is 7 inahes high and 14 inches in diameter, and is n d y filled with solid glass balls& to $ inch in diameter. The inlet tube passes to the bottom of the bottle, and has its delivery end contracted to +'g inch. The outlet tube just paesea through the stopper. For a first trial on an unknown water three or four bottles are used, each charged with 10 C.C. of the barium hydroxide solution. It is advkable to add a little phenolphthalein to the sample of water used, since, if the current of air is too rapid, some of the half-bound carbonic acid may be driven off, when the monocarbonates formed will at once give a pink colour. The air necessary is conveniently supplied from a rubber bag of 1 quart size inflated by means of a bicycle-pump. Each bottle holds about 30 C.C. of liquid, A. G. L. Detection of Traces of Bromine and Iodine in Running Water. N. A . Orlow. (Farmaz. Journ., 1903, xlii., 1737 ; through Chem. Zeit. Rep., xxviii., 36).- Freshly precipitated silver chloride is folded up in a hardened filter-paper, and the packet, fastened to a piece of string, is immersed for twenty-four hours in the spring. If the water contains bromine or iodine, some of the silver chloride will be converted into the bromide or iodide. A. G . L.