NEWS

When the acids are dissolved in the soda, which takes about half a minute, the blowpipe is again removed, the lid is raised a little, and according to the amount of acids present some crystals of sodium nitrate (not potassium nitrate) are thrown in, at the most enough to cover the tip of a knife-blade; the melt is again covered, and heated with a long blowpipe flame, so that it touches the edge of the lid, for eight or ten seconds, so that still unchanged nitrate must be present. The whole process is finished in from one to one and a-half minutes.

When cold the melt is dissolved in hot water, which is best done by adding some water to the crucible after cooling and warming with a small flame. The melt dissolves very quickly, and it is only necessary to rinse the contents of the crucible into a beaker. Thus a great quantity of liquid is avoided, and much time is saved.

As we have said, after filtering it is found that the filtrate contains only very little titanium.

If sulphuretted hydrogen gas is led into the filtrate in the cold, a greyish white precipitate is at once formed; after some time it becomes more voluminous, and contains all the dissolved titanium, while the liquid is quite free from titanium. Thus this method provides a means of separating both niobic and tantalic acid quantitatively from titanium. Niobate and tantalate solutions, prepared by melting niobic or tantalic acid with soda and saltpetre, are unchanged when sulphuretted hydrogen is led into them; i.e., they give no precipitates, and at the most the solutions only become yellow owing to the formation of polysulphide.

The filtrate was always free from titanium; after being acidified with sulphuric acid it gave with hydrogen peroxide a very slight yellow coloration, which could not be estimated quantitatively, and might, moreover, be caused by the presence of a small amount of iron.

In precipitating with sulphuretted hydrogen the following rules must be observed:

Sulphuretted hydrogen is led into the not too concentrated liquid in the cold until the precipitate almost immediately formed becomes no more abundant. It is allowed to stand for some time in the cold, as the precipitate, which is originally difficult to filter, settles, and finally filters well. The precipitate must be washed with sodium polysulphide solution.

The two titanium precipitates-metatitanate and sulphuretted hydrogen precipitate-are treated on the filter with warm sulphuric acid containing about 5 cc. of 3 per cent hydrogen peroxide (prepared from perhydrol), the two solutions are united, the pertitanic acid is reduced with sulphurous acid, and the titanic acid is precipitated as Ti(OH), with ammonia.

The sulphuretted hydrogen filtrate which contains the niobic and tantalic acid is boiled to drive off the excess of sulphuretted hydrogen, acidified with sulphuric acid, and tested for any titanium present with hydrogen peroxide.

If the sulphuretted hydrogen has been led in for long enough there is never any fear that titanium is still in

If the filtrate is found to be free from titanium (it must be proved that any slight yellow coloration is not due to iron), sulphurous acid is added, the liquid is warmed, the precipitate formed is allowed to settle and filtered off. We must now point out some precautions which must be observed in igniting the titanium, niobium, and tantalum hydroxide precipitates.

The precipitates of the hydrated acids must be ignited only when they are dry, and preferably apart from the filter, because otherwise reduction is likely to occur; to reoxidise reduced titanic, niobic, or tantalic acid is very difficult and tedious.

These reduced oxides are blue-black or black in colour, and are not again oxidised to the white oxides readily, either by nitric acid nor by ammonium nitrate. With saltpetre the oxidation is effected instantaneously, but this oxidising agent is naturally not suitable for use in quantitative analysis because it is very difficult to remove it, and because alkaline salts of the acid earths are formed.

It is therefore necessary when igniting the hydroxides to dry the filter thoroughly in the drying oven, to separate the precipitate as far as possible from the filter, to ignite the latter by itself on the porcelain crucible lid with the addition of ammonium nitrate, and then to add it to the contents of the crucible. The niobic acid thus obtained is yellow when hot, and on cooling still possesses a yellow tinge; tantalic acid is yellow both when hot and cold, and titanic acid is dark yellow when hot and light yellow when cold.

We must mention that even small quantities of titanic acid may be detected in tantalic acid by the fact that the latter becomes lemon-coloured when heated, and is never perfectly white on cooling. Titanic acid, especially on heating, possesses a very strong colouring power.

We then tried a second oxidising agent, namely, sodium peroxide.

3. Fusion with Sodium Carbonate and Sodium Peroxide. -Niobic and tantalic acids, when fused with this mixture, give a melt which is readily soluble in water.

Titanic acid melts with much frothing, and gives a dark red liquid which becomes quite white on cooling.

When boiled with water from this melt a copious precipitate of sodium titanate is obtained, but the filtrate still contains titanium. On cooling, a turbidity results, which increases on further cooling. When filtered off it gives a distinct yellow coloration with sulphuric acid and hydrogen peroxide, and thus consists of titanium. The examination of the filtrate for titanium with the same reagents always shows that titanium is still present in it.

4. Fusion with Soda and Borax.-If titanic acid is fused with soda and borax in the proportion 2 of soda to 1 of borax, the melt on treatment with hot water leaves all the titanic acid behind in the form of a white powdery precipitate. The filtrate gives no trace of a yellow coloration with sulphuric acid + hydrogen peroxide, and the precipitation is thus quantitative.

On the other hand, niobic and tantalic acid, when fused with these substances, show quite different properties. The niobium melt dissolves easily in hot water, the tantalum melt equally easily in cold.

Hence it was thought that a method of quantitatively separating the acid earths from titanium had been found, but unfortunately the disturbing influence of niobic and tantalic acids again takes effect to a very marked degree; the solvent action of niobium in the soda-borax melt is so great that even in the presence of fairly large amounts of titanic acid, the latter is completely kept in solution, and only in presence of a considerable excess of titanic acid can a residue of it be obtained.

If about equal amounts of niobic and tantalic acids are fused with this mixture and the melt is treated with hot water, a clear solution containing all the titanium is

obtained, and however long it is boiled not the slightest turbidity is produced.

Very small quantities of niobic acid are sufficient to keep a large amount of titanic acid in solution; tantalic acid has not such a marked effect, but it does retain titanic acid in solution.

Thus the addition of borax seems to increase considerably the solvent power of niobic acid, either in the process of fusion itself or when water is added. Possibly this unexpected effect is due to the presence of boric acid which has been formed by the hydrolytic decomposition of a solution of borax.

This fusion mixture has a very strong solvent effect on niobic and tantalic acid; a melt which in the liquid state covered the bottom of a fairly large platinum crucible to a depth of about 2 cm. without any difficulty dissolved 25 grms. of niobic acid in very short time.

It is also a very good mixture for opening up minerals; e.g., rutile. In this case in suitable conditions it would probably lead to a quantitative separation of titanium and aluminium, which would supersede the very lengthy acetic acid separation of Gooch.

The addition of saltpetre to this fusion mixture does not have the same good effect in opening up niobic and titanic acid as is the case when soda alone-without the boraxis used. Also experiments with

5. Borax without the addition of soda and saltpetre gave no result. The acids form colourless borax glasses which are very difficultly soluble in cold water, and this melt cannot be used for a separation.

6. Fusion with Potassium Cyanide and Caustic Potash. -When niobic or tantalic acid is fused with potassium cyanide and enough caustic alkali to dissolve the acid in question, in the first case a melt of potassium niobate, very soluble in hot water, is obtained, and in the second case a rather less soluble melt of potassium tantalate is formed. Titanic acid when treated similarly gives an absolutely insoluble titanate.

If a mixture of the two acids, i.e., niobic or tantalic acid with titanic acid, or all three together, is fused with potassium cyanide and caustic potash, in almost all cases the titanium remains quite insoluble, and it is seldom necessary to fuse the acids a second time in order to separate them completely from titanium.

This method is very simple and rapidly performed; care must be taken that the caustic alkali is not present in excess. If no caustic alkali is present most of the acid earths remain undissolved, some titanium (never very much) is attacked, but the caustic alkali possesses such a strong solvent action on niobic and tantalic acid that even small amounts of alkali are enough to bring them into solution. We find that the best proportion is 6 parts of potassium cyanide to I of caustic alkali for about equal quantities of acid earths and titanic acid; as the amount of acid earth increases and with it the quantity of caustic alkali, more potassium cyanide must also be used.

The process itself is very simple. The potassium cyanide is fused in a silver crucible, the alkali being added at once (the former then fuses more rapidly). The liquid melt usually looks rather dark owing to the separation of carbon. When frothing has ceased the mixture of acids is added; the melt swells up, and becomes less liquid. It is heated for about half a minute, the flame is taken away, and the crucible allowed to cool. The greyish white melt is then treated with hot water, preferably in the crucible itself; it dissolves very easily, and the solution is poured

out into a beaker.

The crucible must be well rinsed out,

for the titanic acid persistently clings to the sides. Then the liquid is diluted with about the same volume of hot water and boiled, as potassium tantalate does not dissolve very easily. (With potassium niobate it is not necessary to boil).

The greyish white-looking metatitanate is filtered off, dissolved in sulphuric acid hydrogen peroxide, reduced with sulphurous acid, and precipitated with ammonia. The filtrate, which contains the potassium niobate or

| tantalate, is acidified with hydrochloric acid, and tested with hydrogen peroxide for titanium. If the directions are followed a slight titanium coloration can just be detected (more often a very similar ferric salt coloration appears, due to the presence of iron in the potassium cyanide). Usually the titanium coloration is so slight that it can be neglected. But to make quite sure the acid earths can be precipitated with sulphurous acid and the fusion repeated.

As regards the precipitation of the niobate or tantalate, in this case hydrochloric acid is always used in order to precipitate dissolved silver as silver chloride, the liquid is boiled till all the hydrocyanic acid has been expelled, and the precipitated acids are dissolved in hydrogen peroxide. The silver chloride can then be filtered off.

It is necessary to boil till all the hydrocyanic acid has been driven off; otherwise the precipitation is incomplete, for the presence of hydrocyanic acid apparently has a very disturbing effect. Small quantities of acid earths give in presence of hydrocyanic acid only a slight turbidity with ammonia, and a flocculent precipitate is formed only after standing over-night.

7. Fusion with Soda and Sodium Sulphite.-If niobic or tantalic acid is fused with soda and small amounts of sodium sulphite are added at intervals, white fusion products are obtained; they are soluble in hot water, while titanic acid remains undissolved. But if a mixture of niobic or tantalic acid with titanic acid is fused with the above mixture, and the melt is treated with water again, nearly the same phenomena appear as were observed in the case of the soda melt. Thus part of the titanium is retained in solution with all the niobium or tantalum, but the unprecipitated portions of titanic acid are much smaller than in the case of the soda melt.

When about 0.15 grm. TiO2 is used, the quantity of titanium which remains in the filtrate cannot be detected colorimetrically; by comparing the solution with a strongly diluted pertitanic acid solution of known strength, the amount was found to be o'002 grm. Ti per litre; thus a very small proportion.

On leading carbon dioxide into this alkaline solution, in the course of half-an-hour a small amount of white precipitate formed, and was filtered off. It gave distinctly the sulphuric acid + hydrogen peroxide reaction, while the filtrate was absolutely free from titanium. It was thus to be expected that by this method titanium could be quantitatively separated from niobium and tantalum.

Experiments in which this alkaline melt was extracted with dilute alcohol instead of with water gave the same results. The amount of titanium in the solution remained the same whether water or alcohol was used. The only difference was that when 70 per cent alcohol was used soda and niobate or tantalate were insoluble and were precipitated.

We then investigated the action of acid melts on the mixture of acid earths with titanic acid, when the following results were obtained :

:

B. Separation Experiments with Acid Melts. 1. Boiling with Concentrated Sulphuric Acid.-Both English sulphuric acid (66°) and fuming sulphuric acid were used as well as sulphuric acid containing two parts of acid to one part of water. All three acids behaved in exactly

the same way.

Titanic acid is completely dissolved on heating with concentrated sulphuric acid, the solution remains quite clear when poured into the same volume of water, and only begins to get turbid after boiling for a quarter of an hour. Niobic acid also dissolves in hot concentrated sulphuric acid; the solution remains clear when poured into water, but becomes turbid on standing (over-night) and on boiling. Tantalic acid is only slightly dissolved on boiling with concentrated sulphuric acid and is turbid when poured into water. A small amount, however, remains in solution even on boiling.

If a mixture of titanic and niobic acid is boiled with concentrated sulphuric acid and the solution is poured into water, the liquid remains clear. On standing over-night the above mentioned niobic acid precipitate forms and increases in amount on boiling. It is quite free from titanium, but unfortunately the niobic acid is not precipitated quantitatively, and the same thing happens with

tantalum.

It was also useless to pour the solution of the acid earths in concentrated sulphuric acid into strongly saturated solutions of sodium sulphate, magnesium sulphate, or potassium sulphate-the result was no better, and niobic acid remained partly in solution.

The sulphuric acid niobium solution, when poured into concentrated ammonium sulphate solution, remained clear even after standing for eight days.

A sulphuric acid titanic acid solution remained clear on boiling with 7 per cent acetic acid, even if boiled for hours. 2. Fusion with Potassium Monosulphate. - Experiments with this salt confirmed Warren's statement, according to

which the bisulphate melt of the acid earths, when treated with cold water, gives only a very incomplete separation of the three acid earths.

If the potassium monosulphate melt of titanic acid is treated with cold water, meanwhile leading in cold air (to accelerate solution), all the titanic acid remains in solution.

In the same circumstances niobic and tantalic acid are precipitated, the former very incompletely and the latter better, but not quantitatively, as many experiments showed. If the melt is treated with hot water, titanic acid is also precipitated.

3. Fusion with Sodium Monosulphate. This melt has the same properties as the potassium monosulphate melt, but does not dissolve in water so easily.

4. Fusion with Ammonium Monosulphate.-While melts of tantalic acid when boiled with water are precipitated quantitatively, the titanium melt remains clear, even when boiled for two hours, if the water which evaporates is replaced by filling up the vessel, and only at the end of that time it begins to show a distinct turbidity. Experiments to separate tantalic acid from titanic acid in this way failed, because this acid carries down titanic acid with it.

A repetition of the fusion process with the acids already precipitated once, i.e., those which titanic acid had carried down in the first separation, gave only an inconsiderable

decrease in the amount of titanium.

We now tried to separate the acids by melting with potassium monosulphate and treating the solution with5. Sulphurous Acid.-It has already been mentioned that niobic and tantalic acid are precipitated quantitatively from strongly acid solution by sulphurous acid.

If a pertitanic acid solution is boiled with excess of sulphurous acid, i.e., it is first decolorised by sulphurous acid, and then more of the latter is added, even after long boiling no titanic acid is precipitated.

The mixture of the three acids was fused with potassium monosulphate, the melt extracted with hot water, and the

resulting precipitate dissolved by adding hydrogen peroxide. Sulphurous acid was now added until the liquid was decolorised, then a further moderate excess added, and the liquid boiled.

The resulting white flaky precipitate was filtered off, washed, and tested with sulphuric acid and hydrogen peroxide. It showed a very strong titanium coloration. The filtrate, on the other hand, which night be expected to contain titanium by reason of its property of not precipitating with sulphurous acid was found to be quite free from titanium. Thus by precipitating the acid earths all the titanium was carried down, and the action of the acid earths was the same even with a fairly large excess of

titanium.

An attempt was made to get a better result by altering the experimental conditions. Sulphurous acid was added drop by drop to the hot solution containing hydrogen peroxide till decoloration occurred, then some more drops of sulphurous acid were added (the acid earth precipitate at once formed); about an equal volume of cold water was added to the hot solution (to lower the temperature of the liquid), and it was at once filtered through as large a filter as possible. The precipitate was washed with cold dilute sulphurous acid till the filtrate gave no yellow coloration with hydrogen peroxide.

The precipitate when treated with sulphuric acid + hydrogen peroxide gave a distinct yellow coloration, and the filtrate also, more decidedly than the precipitate.

The precipitate now in solution was again precipitated as above, and thus by repeating the solution and precipitation five times a niobic or tantalic acid precipitate almost completely free from titanium was obtained if the amount of titanic acid was not too great to begin with.

If a very large excess of titanic acid was present the acid earth in question retained a small amount of it, which, however, was easily detected by the hydrogen peroxide and sulphuric acid reaction.

If excess of sulphurous acid is added to a cold solution of the three acids containing hydrogen peroxide, and it is allowed to stand over night, an abundant white precipitate is obtained which is free from titanium, while the solution contains large amounts of titanium. It would perhaps be possible to obtain thus a separation which would be satisfactory in all cases.

The presence of phosphoric acid impedes the precipitation of the acid earths by sulphurous acid, and makes the precipitate richer in titanic acid.

6. Hydroxylamine.-Hydroxylamine reduces a hot pertitanic acid solution without precipitating it. It precipitates a perniobic acid solution on boiling, but not quantitatively. 7. Sulphuretted Hydrogen.-It was also observed that from sulphuric acid solution in the cold sulphuretted hydrogen precipitates both acid earths mixed with sulphur, while titanium remains in solution. We shall return to this question later.

(To be continued).

Composition of Essence of Cloves.-H. Masson.The author has isolated two aldehydes and an ester from essence of cloves. The ester is methyl salicylate, and one of the aldehydes has been identified with a-methylfurfurol. The other is a dimethylfurfurol, but the position of the methyl and carboxyl groups in the furfurane nucleus has not been determined.-Comptes Rendus, cxlix., No. 19.

COATING SOUNDING TUbes.

By CHARLES E, MUNROE, Professor of Chemistry, the George Washington University, Washington, D.C.

It is well known that in many places the land dips so gradually under the sea that the approach toward the shore may be detected at a considerable distance from it by sounding, and hand sounding, with lead and line, has long been practised. This operation, however, is a difficult one to carry out, except in quite shallow water and when the vessel is nearly at rest. It is obvious that greater safety in navigation was attained when Sir William Thomson (Lord Kelvin) invented his sounding machine, since by its use it has become possible to take flying soundings in depths of from 50 to 100 fathoms every ten minutes, while the vessel is making 14 to 18 knots per hour. ("On Compass Adjustment of Iron Ships and on a New Sounding Machine," Sir William Thomson, Journ. Royal United Service Institution, 1874, xxii., 90; and "Sounding Machines for the Prevention of Strandings," Prof. Lambert, Journ. Royal United Service Institution, 1891, xxxv., 765). This he accomplished by using wire in place of the old hempen lead line and applying Mariotte's law in measuring the depth attained, thus eliminating from consideration in the measurement the variable lengths of wire which must be payed out in attaining the same depth under different speeds. The depth is ascertained by means of a glass tube, closed by a cap at its upper end, which is enclosed in the sinker so as to be kept upright, and be protected from fracture, while the water has easy access to its open end. A pressure of five fathoms of sea water equals that of one atmosphere, and the water will rise the higher in the tube the deeper the device sinks below the surface of the sea. To record the height to which the water rises within the tube, and therefore the depth to which the weight sinks, the interior of the tube is coated with red silver chromate, which reacts with the salt in the sea-water to form white silver chloride and soluble sodium chromate, which dissolves out; consequently the colour is discharged from the coating on the tube to the highest point reached by the water.

It is apparent that a coated tube can be used but once for a given depth, or for anything less than that depth, and that it must be re-coated for re-use. This process was a trade secret, and because of the inconvenience and expense of having to send the tubes consider able distances for treatment, attempts have repeatedly been made to ascertain how this re-coating can be best accomplished. In the method devised by Surgeon Paul Burrill, of the Compagnie Générale Transatlantique, it is directed to shake up about 16.5 grms. of finely ground silver chromate with 50 cc. of photographic collodion, allow the mixture to stand for one-half hour, and then use the supernatant liquid for coating the tubes. This mixture yields coatings which were found to be of a dull brownish red colour, which react sluggishly with sea-water, and which are apt to detach themselves from the tube. Experiments with albumen gave no better results, but gelatin was found to serve admirably as the medium for forming the film. At first the freshly prepared solid silver chromate was mixed with the medium, as in Burrill's process, but later it was found better and simpler to form the silver chromate within the medium. The coating liquid, as finally adopted, consisted of 100 grms. of Le Page's liquid glue, to which was added, with stirring, first 3'4 grms. of finely powdered silver nitrate, and then 1'95 grms. of finely powdered potassium chromate, the mixture being stirred with a glass rod until the bright red colour was developed to its maximum brilliancy throughout the mass. This quantity of the mixture is sufficient to coat ten dozen tubes.

In the meantime the tubes are cleansed for re-coating by removing the caps from the top and immersing the tubes in concentrated sulphuric acid for about five minutes, so

as to destroy the coatings left in them; then washing with water to remove acid; then immersing in ammonia water for about ten minutes to dissolve any silver chloride present; then washing with distilled water again; and then drying thoroughly. The coating is applied to the well dried tube by attaching a rubber bulb to one end, dipping the other end in the gelatin-chromate mixture, and sucking the mixture up to the height of about 10 cm., when the bulb is removed, the tube overturned, and placed in a rack (like a test-tube rack with a trough about it to receive the drip) to allow the excess liquid to flow down the tube. This viscous liquid flows slowly, hence the tubes are allowed to remain in the rack for twenty-four hours. The small plug of gelatin-chromate mixture, which has hardened in the end of the tube, is removed by inserting a fine wire and revolving it until the tube is clear, and then the tube is ready for capping. This is done by placing a disk of tin or copper foil on the end of the tube, filling the cap with molten sealing-wax, forcing the tube into it, and wiping the excess wax off from the outer walls of the tube. The use of the foil is recommended because it is essential that the interior length of the tube shall be invariable, and it was found that where tubes had been capped without the use of the disk the sealing-wax had been forced into them to varying extents.

When the tubes are prepared in the manner just described they are coated evenly with a translucent brilliant red coating, which reacts instantly on contact with salt water, the colour being sharply and immediately discharged to the height to which the water has risen within the tube. They are very sensitive, and will remain so if stored in a cool dry place, out of contact with the light, as the potassium nitrate seems to exert a preservative effect. If, however, they are heated or exposed to direct sunlight, the colour changes and the sensitiveness decreases. After one hour's exposure to bright sunlight the coating of a finished tube had changed in colour from brilliant red to dark chocolate. After resting a tube for an hour upon an ordinary steamheating radiator in operation, the coating of the tube had become chocolate coloured and opaque, and it had softened so as to run. The manufacturing operations must likewise be conducted in diffused light and in only a moderately heated room, to avoid changes of a similar nature to those just described taking place, and it is essential that the coating mixture should be prepared immediately before its application to the tubes. The process is so simple a one that it may easily be carried out on shipboard.—The Chemical Engineer, x., No. 2.

RAPID ANALYSIS OF BABBITT METAL.

IN the August issue of the Journal of Industrial and Engineering Chemistry Messrs. Percy H. Walker and H. A. Whitman propose the following scheme for the analysis of Babbitt metal. The novelty of their procedure depends upon the employment of a separate portion of the alloy for each determination and the complete solution of the metal in each instance before it is determined. The authors have very thoroughly tested the method, and obtained better results with it than with other technical methods. The details follow:

Copper.- Weigh I grm. of the alloy into a 250 cc. beaker, add 20 cc. hydrochloric acid and 5 cc. of water, heat, and complete solution by adding nitric acid in small amounts; with most alloys solution can be effected in a very few minutes, and without adding more than 1 or 2 cc. of nitric acid. Evaporate off the acid on a steam-bath. It is not necessary to carry to complete dryness, but practically all the acid should be driven off and the residue should be pasty. Add 25 cc. of a solution made of 200 grms. tartaric acid, 260 grms. of potassium hydroxide, the whole being made up to 500 cc. with water. Heat on the steam-bath until solution is completed, add 25 cc. water,