chouc stopper, through which pass the tube of a separator bulb with a good stopcock and a long (3 to 4 dem.) delivery tube bent downwards at an acute angle and turned up at the end. The nitrate solution is boiled in the flask (the delivery tube dipping into the mercury trough) until every trace of air is expelled. The stopcock is then closed, a boiling hot mixture of ferrous chloride and hydrochloric acid is poured into the bulb, and the lamp is removed. As soon as the mercury begins to rise in the delivery tube, the ferrous solution is allowed to flow in, the lamp is replaced, and the nitric oxide boiled out as usual. A little of the ferrous solution should remain in the bulb to act as a seal. M. J. S.

Determination of Phosphoric Acid. By A. ISBERT and A. STUTZER (Zeit. anal. Chem., 26, 583-587).-The method based on the determination of the ammonia in the phosphomolybdate precipitate (Abstr., 1887, 526) is confirmed. A further simplification consists in washing the yellow precipitate with cold water instead of with ammonium nitrate solution. The compound of silicic acid with ammonia and molybdic acid is soluble in pure water although insoluble in ammonium nitrate. On the other hand, the phosphomolybdate requires 10,000 parts of cold water for its solution. The removal of silica by evaporation may therefore be omitted. The precipitate is allowed to subside completely at 70°, and filtered off after cooling. It is thrown with its filter into a flask, and distilled with soda into standard acid, which is then titrated back with baryta, using corallin as indicator. One part of nitrogen in the precipitate corresponds with 1-654 parts of phosphoric anhydride. Test analyses with known quantities of phosphate, with and without silicic acid, and comparative assays of phosphatic manures by the above and the gravimetric process, show that for commercial purposes the method is sufficiently accurate. M. J. S.

New Methods of Estimating Arsenic in Pyrites. By J. CLARK (J. Soc. Chem. Ind., 6, 352-355).—Precipitation Process.Three grams of the finely powdered pyrites is mixed in a platinum crucible with four times its weight of calcined magnesia and soda, and the mixture heated for about 10 minutes over a moderately low Bunsen flame. The contents of the crucible are then extracted with boiling water and filtered. The filtrate, which should be green in colour owing to the presence of iron, is acidified with hydrochloric acid, and the solution, which is now nearly colourless, is boiled for a few minutes, when the arsenic sulphide will separate along with sulphur. To ensure complete precipitation of the arsenic, it is always advisable to saturate the solution with hydrogen sulphide. The precipitate is then thrown on to a filter, washed, dissolved with ammonia, and the solution evaporated to dryness on a water-bath. The residue is treated with nitric acid and the arsenic in the solution either estimated as magnesium ammonium arsenate, or precipitated as silver arsenate, and the arsenic calculated from the silver as determined volumetrically by Volhard's process, or gravimetrically by cupellation, as recommended by Richter.

Distillation Process.-About 17 gram of the finely pulverised pyrites is introduced into a platinum crucible with six times the weight of the above mixture, and heated for an hour over a low Bunsen flame. The contents of the crucible are transferred to a flask, moistened with water, and dissolved in strong hydrochloric acid. The flask, which is fitted with a funnel tube, having the end drawn to a point and dipping under the liquid, is then connected with a small glass condenser, to the end of which a straight calcium chloride tube is attached, and by means of the funnel tube a considerable excess of cuprous chloride dissolved in strong hydrochloric acid is introduced. The contents are then slowly distilled into water for an hour, when a fresh quantity of hydrochloric acid is introduced, and the distillation continued for hour. The whole of the arsenic will now be found in the receiver, but it is always advisable to add a little more hydrochloric acid, change the receiver, and test the distillate. The arsenic is then precipitated as sulphide, or it is titrated with iodine in the usual way. D. B.

Estimation of Silicon in Iron and Steel. By J. J. MORGAN (Chem. News, 56, 221).—The author criticises Turner's statements (Abstr., 1887, 1140), and states that silica may be obtained free from iron and phosphorus in the following manner :-The solution obtained by dissolving iron in aqua regia is evaporated to a thick syrupy consistence, treated with hydrochloric acid, and the precipitated silica well washed with dilute hydrochloric acid and water, when it is found to be free from both iron and phosphorus. D. A. L.

Estimation of Silicon in Iron and Steel. By T. TURNER (Chem. News, 56, 244–245).-A reply to Morgan (preceding Abstract). Whilst the process described above will give fairly accurate results with iron containing under 1 per cent. of phosphorus and about 1 per cent. of silicon, this is not the case with commoner irons containing 2 per cent. of phosphorus and 3 to 4 per cent. of silicon.

Indirect Determination of Alkalis in Presence of Lithium. By K. KRAUT (Zeit. anal. Chem., 26, 604-605).—The metals are weighed as nitrates, and the nitric anhydride then expelled by fusion with silica. The calculation is made in the usual manner.

Chlorides are converted into nitrates by treatment with silver nitrate. Phosphates are dissolved in a little nitric acid, about an equivalent quantity of silver nitrate is added, and then freshly precipitated silver oxide to neutrality. The excess of silver in either case is removed from the filtrate by hydrocyanic acid. This method is not applicable to sulphates, since barium sulphate cannot be freed from lithium salts by washing.

M. J. S.

Determination of Ammonia in Commercial Products. By J. M. MILNE (J. Soc. Chem. Ind., 6, 423).—Some time ago a German committee recommended the liberation of the ammonia from phosphates, manures, and other commercial products, by boiling with magnesia instead of alkaline hydroxides, and absorption in a measured

excess of standard sulphuric acid. One great advantage of this modification is that the contents of the distilling flask boil quite quietly, and can be brought nearly to dryness without spirting if the gas flame is properly regulated. The author has used this method for some time with very satisfactory results. It is necessary, however, to observe the following precautions:-(1) The steam containing the ammonia should be thoroughly condensed as it passes over. (2) The end of the condenser tube should not dip beneath the surface of the sulphuric acid in the bulb flask. (3) In order to ensure complete absorption of the ammonia, a small U-tube containing a little of the standard acid should be attached to the exit tube of the flask.

D. B. Assay of Silver containing Small Quantities of Bismuth. By J. SCULLY (see p. 108).

Estimation of Mercury in Urine. By L. BRASSE (Compt. rend. Soc. Biol. [8], 4, 297-300).—Simple electrolysis is insufficient, inasmuch as certain organic matters are deposited along with the mercury on the electrode. To obviate this error, the author treats 100 c.c. of urine with 10 c.c. of hydrochloric acid, places in the mixture a small coil of thin sheet brass 1 cm. broad by about 50 cm. long, and allows the interaction to go on for a day. The coil is then removed, washed with alcohol and ether, dried, transferred to a porcelain crucible and heated. The mercury vapour is condensed on a concave cover of gold kept cool by distilled water. The difference between the weight of the dried cover before and after heating gives the amount of mercury. J. P. L.

Estimation of Iron in Chars. By R. DAVIDSON (J. Soc. Chem. Ind., 6, 421). Having tested the accuracy of the stannous chloride process for the estimation of iron in the case of substances such as animal charcoal, containing only from 0.1 to 10 per cent. of ferric oxide, the author confidently recommends it in preference to either the "permanganate " or " dichromate " process. D. B.

Determination of Ferrous Oxide in Insoluble Silicates. By A. H. CHESTER and F. I. CAIRNS (Amer. J. Sci., 34, 113-116).-In their examination of the crocidolite from Rhode Island, the authors determined the ferrous oxide by means of ammonium fluoride. Half a gram of the pulverised mineral is placed in a large platinum crucible over a water-bath, and a slow stream of carbonic anhydride is carried into it. When the air is expelled, a few drops of concentrated sulphuric acid is added, then some ammonium fluoride. Similar additions are made from time to time until the mineral is completely decomposed. The contents of the crucible are then emptied into a beaker containing cold water. The solution is diluted, and the iron determined by means of potassium permanganate in the usual manner. B. H. B.

Estimation of Titanic Oxide. By L. Lévy (Compt. rend., 105, 754-756). The author has investigated the conditions necessary to ensure accuracy when using the ordinary method of fusing with

potassium hydrogen sulphate, extracting with water, and precipitating the titanic oxide by prolonged boiling. The solution should contain 0.5 per cent. of free sulphuric acid; if less, the precipitate is impure; if more, precipitation is incomplete. The presence of zinc in the solution is without influence on the result, provided the proportion of free acid is 0.5 per cent., and the same is true of copper, magnesium, and aluminium, but in presence of ferric sulphate the result is always too high.

The best method of procedure is as follows:-The fused mass is mixed with sufficient sulphuric acid to convert the whole of the potassium into the hydrogen sulphate, solution being thus greatly accelerated, and the liquid is then carefully neutralised with potassium hydroxide, free sulphuric acid added to the extent of 0.5 per cent., and the solution boiled for six hours. C. H. B.

Determination of Antimony. By F. MUCK (Zeit. anal. Chem., 26, 600-602).-The precipitate of trisulphide is dried by suction. until it can be detached from the filter. The filter is washed with warm ammonium sulphide in which much free sulphur has been dissolved, this polysulphide having a far greater solvent action than the monosulphide. The solution is evaporated in a porcelain crucible. A convenient way of doing this is to support the crucible on a glass triangle in a deep glass basin containing a little sulphuric acid, and covered closely with a glass plate. On gently heating the basin on a bed of asbestos, the liquid evaporates rapidly without spitting. detached precipitate is then added and the whole dried. The free sulphur is removed by treatment with a mixture of carbon bisulphide and chloroform, and the antimony sulphide is converted into tetroxide for weighing. M. J. S.

Delicate Test for Bismuth. By F. B. STONE (J. Soc. Chem. Ind., 6, 416). This test depends on the fact that a strong solution of potassium iodide produces a bright yellow colour when added to a very dilute solution of bismuth sulphate containing only a small quantity of free sulpuric acid. 1 part of bismuth oxide in 1,000,000 parts will show a distinct coloration. Very small quantities of bismuth may also be estimated colorimetrically by means of this test.

D. B.

Detection of Nitrates in Well Water. By O. BINDER (Zeit. anal. Chem., 26, 605-606).-The method depending on the reduction to nitrite by zinc, and testing with potassium iodide and starch, fails if too much zinc is used. A trace of zinc powder shaken with the liquid answers better than compact zinc. M. J. S.

Water Analysis. By O. BINDER (Zeit. anal. Chem., 26, 607).— Liquids, such as natural waters, evaporated over a free gas flame, become contaminated with sulphuric acid from the products of combustion. M. J. S.

Elementary Analysis of Highly Volatile Organic Liquids. By G. KASSNER (Zeit. anal. Chem., 26, 588-590).-The combustion

tube is prolonged at the posterior end beyond the furnace, and is bent upwards at an angle of about 45°. A plug of asbestos is placed at the bend. The bulb containing the liquid is introduced at this end, and rests against the asbestos plug with its capillary tube pointing upwards. The bulb having been cooled before breaking the point of the capillary tube, can be introduced without the escape of any of the liquid, and the gradual expulsion of the contents can be watched and regulated, since the vaporised liquid condenses in the capillary tube, and is driven out in the form of minute drops. These are immediately evaporated and swept forward by the current of oxygen passed through the tube. The more volatile the liquid, the longer and narrower should be the capillary tube. The portion of the combustion tube which is to be heated is filled with platinised asbestos (see Kopfer, ibid., 17, 1). For substances which burn with difficulty, however, cupric oxide cannot be dispensed with. For arresting halogens, a plug is employed prepared by shaking chopped asbestos with finely divided, reduced silver. A stream of hydrogen (free from arsenic or antimony) passed through the hot tube regenerates the metallic silver after it has absorbed a halogen. M. J. S.

The Stalagmometer. By J. TRAUBE (Ber., 20, 2824-2835).Applications of the stalagmometer (this vol., p. 91) to the estimation of alcohol in wine, beer, and liqueurs, and of acetic acid and alcohol in vinegar. Tables are given for use at temperatures between 10° and 30° for alcohol, and 11° and 29° for acetic acid, for percentages up to 10 per cent. by weight of the pure substance in each case.

W. P. W.

Recognition of Pyrogallol. By G. KLIEBAHN (Zeit. anal. Chem., 26, 641).-Pyrogallol when fused with ammonium oxalate yields ammonium rufigallate, which dissolves in water with red colour, and gives the following characteristic reactions:-Potassium ferricyanide and potassium dichromate, a dark-brown precipitate insoluble in alcohol. Ferric chloride, no black coloration. A few drops of acetic acid, then potassium cyanide and mercurous nitrate, a black precipitate. Sodium nitroprusside and platinic chloride, no precipitate or change of colour. Potash, a change to brown, but not to black.

M. J. S.

Estimation of Grape-sugar in Urine by Robert's Method. By V. BUDDE (Pflüger's Archiv, 40, 137-172).-The fermentation method of determining the amount of sugar in diabetic urine consists in multiplying the difference in specific gravity before and after removal of the sugar by fermentation, by a constant factor found by control titration experiments in which the percentage so found was divided by the difference in the specific gravities. Worm-Müller has stated (ibid., 37, 479-510) that this factor is constant, namely, 230. This paper is devoted to showing mathematically that from its very nature this factor is a variable one, increasing as the percentage of sugar diminishes. W. D. H.