PART III.-Reduction by Magnesium Powder of Silicic Anhydride.

Magnesium powder readily reduces silicic anhydride in presence of air without external heating during the reaction; the products consist of free silicon, one or more of the silicides of magnesium, magnesium oxide, and possibly silicon monoxide.

It has been shown previously that in similar actions the air plays an important part, more especially in the initial stages of the reduction. In the experiments now described the interaction has been studied in absence of air, and mixtures containing the following varying quantities of the constituents have been made to react in vacuo and the products examined.

Analysis of the Mixture resulting from the Reaction. It was thought that by using excess of Mg it would be possible to use up the whole of the SiO2, and by subsequent treatment of the residue with acids to obtain pure silicon. A mixture was therefore made consisting of equal parts of SiO2 and Mg; for the reaction demanded by the equation 2Mg+SiO2 = 2MgO + Si, 48-7 parts Mg are required to 60 parts of SiO2.

Twelve reductions were carried out, each time 20 to 30 grms. of the mixture being used; the contents of the crucible from each reaction were powdered, mixed, and analysed. The products consisted of free Mg, unreduced SiO2, two or more silicides of Mg, free Si, MgO, and possibly some silicon monoxide.

(a) Equal weights of each. (b) In proportions Mg+SiO2. (c) In proportions 2Mg + SiO2.

(d) In proportions 4Mg+SiO2.

The magnesium powder was supplied by Kahlbaum, and was found to contain a small amount of MgCO3, which caused an evolution of gas during the reduction.

The silica used was precipitated, and before use was strongly ignited.

The fuse used to start the reaction consisted of a mixture of Al powder and Na2O2 in proportion 4Al to 3Na2O2. The apparatus used was the large bottle of about 3 litres capacity, fitted up as shown in diagram 3, Part I,

The complete quantitative analysis of the mixture has not yet been successfully carried out, owing to the difficulties met with.

The authors are carrying out experiments to throw light on the formation of "monox," and to find certain reliable tests for this substance. Owing to lack of reliable information with regard to magnesium silicides, no complete estimation of these bodies has yet been made.

1. Examination and Estimation of Silicides.—On treatment with strong HCl a large amount of spontaneously inflammable gas was evolved, and on washing and drying the residue at 100° C. and then treating with HF more inflammable gas was evolved. It was found impossible to completely decompose the silicides with HCI; this was either due to (a) a protective layer of SiO2 formed in the

NEWS

1910 reduction, (b) to a film of SiO2 deposited during the action of the acid, (c) to different silicides being present which are unattacked by HCl.

The decomposition by HCl was carried out in an atmosphere of hydrogen or CO2 and also in vacuo, and in each case a large amount of undecomposed silicide remained.

2. Decomposition in CO2 or H.-The weighed powder was placed in the middle flask and just covered with water; H or CO2 suitably washed was passed through the apparatus until the whole of the air was expelled; by adjusting the taps shown a very slow stream of gas was then driven through the apparatus during the experiment. Strong HCI was added very slowly, and a vigorous reaction took place, the evolved gases passing through the three test-tubes, which contained AgNO3 solution.

The AgNO3 solution in the first tube became black immediately, while if the operation was carefully carried out the solution in the last tube remained clear.

The flask was warmed when the reaction had become slow, and H or CO2 passed until the whole of the SiH4 was driven over. The deposited silver was dissolved in HNO3 after filtering and washing, and estimated by standard NH4CNS.

The mixture in the flask still contained undecomposed

silicides.

If the reactions are

(a) Mg2Si+4HCl = SiH4 +2MgCl2,

(b) SiH4 +4AgNO3 = Si +4Ag+4HNO3, then 108 grms. Ag to 19 grms. Mg2Si. In two estimations

I grm. mixture used and 5'9 cc. of o'098 N. NH4CNS. I grm. mixture used and 6.35 cc. of o·098 N. NH4CNS. corresponding to about 1.2 per cent Mg2Si.

The estimation in this manner was abandoned after many attempts.

3. Reaction between HCl and the Mixture in vacuo.The gas was generated by adding concentrated HCl very slowly and carefully to the mixture after exhausting the apparatus (see Fig. 5); the gas evolved was finally driven over into a mercury gas holder by means of freshly boiled distilled water, and was stored out of contact with water.

The gas when first made was spontaneously inflammable, but after storing for some time it lost this power and consisted of almost pure hydrogen, giving no deposit of SiO2 when burnt. (The mixture, after keeping for some time and decomposed in vacuo, gave no spontaneously inflammable gas with HCI, although with HF this was given off rapidly). The gas evolved was estimated as shown later. The residue in the flask, although it showed no reaction on warming with HCl, readily evolved spontaneously inflammable gas with HF.

The authors were not able to estimate the total silicides by this method, but consider that at least two silicides were present.

Method of Analysing the Gas.

A small volume of about 10 cc. of the gas was transferred very slowly into an explosion pipette containing a known volume of pure oxygen.

As soon as a bubble of the gas came into the oxygen a sharp explosion took place and a cloud of SiO2 was produced. This continued until the whole of the gas was transferred. A slight black deposit formed on the bulb, probably due to a small amount of the gas being decomposed by the high temperature of the explosion.

The diminution in volume was observed and the residual gas sparked, the volume again noted, and finally the gas was mixed with electrolytic gas and again sparked.

Knowing the volume of gas used and the contraction after explosion, and assuming that the gas consisted of SiH, and H2 only, the amount of each can be calculated. To illustrate the method of calculation an experiment is given fully.

2 grms. mixture used.

247 3 cc. gas at 19° C. and 760 mm.

The total loss on explosion was 21.7 CC.
For above composition should be 21.9 cc.

A large number of analyses gave the same result, showing the gas to consist of almost pure H mixed with a very small quantity of hydride of silicon, and that, moreover, a very small quantity of this gas is sufficient to inflame the hydrogen when mixed with air or oxygen.

This analysis enables the percentage of free Mg to be found; this was 12'27.

The action of the gas on KOH was examined, but the changes in volume were too small to be measured, showing the existence of traces only of gases other than hydrogen.

Estimation of Total Silicon in the Mixture.

It was thought possible to estimate the Si and SiO2 by (a) dissolving in boiling HCl and weighing the residue left; (b) dissolving the Si in KOH and weighing the SiO2 left; (c) fusing with KOH and estimating the total silica.

Concordant results could not be obtained, and it was found that the finely divided SiO2 dissolved freely in both HCl and KOH, and that any treatment to render SiO2

insoluble would also convert some of the Si into SiO2.

The total silicon was found correctly by fusing with KOH, &c.; it was always necessary to evaporate HCl solutions to dryness and ignite, as the finely divided silica readily dissolved.

Percentage Si found = 22.124.

New Tertiary Glycol.-A. Béhal.-The hydrogena. tion of terpineol in presence of reduced nickel yields a tertiary menthol which is not optically active. The action of sulphuric acid on the alcohol gives a menthene which can be characterised by transforming it into menthone by means of iodine and mercuric oxide and silver nitrate.

Thus pinene can be converted into menthene by means of the following stages :--Pinene, terpineol, hydroterpineol, menthene A, menthene, menthone.-Camptes Rendus, cl., No. 26.

NEWS

Sept. 30,

MISCELLANEOUS SUPPLIES,*

INCLUDING PAINTS AND PAINT MATERIALS, INKS, LUBRICATING OILS, SOAPS, &c.

By PERCY H. WALKER. (Continued from p. 159).

INKS.

Writing Inks.

ALMOST without exception all black inks suitable for record purposes are iron-tannin inks. The determinations of an analytical character which are of value are as follows:1. Specific Gravity.-Determine with a pyknometer at 15'5 C.

2. Total Solids.-Weigh 10 grms. of ink in a flatbottomed platinum or porcelain dish, evaporate to dryness on the water-bath, and then heat in an oven at the temperature of boiling water for two hours; cool in a cator and weigh.

3. Ash.-Burn the residue from the determination of total solids at a low temperature, preferably in a muffle. In order to avoid loss by foaming the dish used should not be too small, not less than 50 cc. capacity.

4. Iron.-Transfer the ash to a small beaker and dissolve in 15 cc. of hydrochloric acid with the addition of stannous chloride at the temperature of the steam-bath; reduce by adding stannous chloride, drop by drop, to the hot solution until the colour is destroyed, and then add one or two drops in excess. Wash the reduced iron solution from the small beaker into a 600 cc. beaker and dilute to about 250 cc. with cold water, add all at once an excess of mercuric chloride, stir, allow to stand a minute, and titrate with standard potassium dichromate solution.

5. Sulphuric Anhydride, SO3.-Determine both iron and sulphuric anhydride in the same sample. Place from 10 to 15 grms. of ink in a platinum dish, add 1 to 1.5 grms. of sodium carbonate previously dissolved in water, evaporate to dryness, ash, extract with water, add bromine water to the extract, boil, render acid with hydrochloric acid, boil off the bromine, and determine the sulphuric anhydride (SO3) by precipitation with barium chloride. Dissolve the insoluble residue in hydrochloric acid and determine iron as described in the preceding section. Or, in case the small amount of platinum (which always goes into solution when iron oxide is dissolved by hydrochloric acid in platinum) causes trouble with the potassium dichromate method, add sulphuric acid, evaporate to fumes, dilute, reduce with zinc, and titrate with potassium permanganate. 6. Keeping in Ink Wells.-Allow the bottle of ink to stand perfectly still at room temperature for three days. Carefully remove the stopper without shaking the bottle, and draw out about 50 cc. with a pipette from the middle of the bottle. Filter this through a dry paper, exposing as little as possible to the air, and place 25 cc. of the filtrate in a clear glass bottle 140 mm. high and 56 mm. in diameter, with a neck 32 mm. in diameter (an 8-ounce salt-mouth bottle). Cover the top of the bottle with a piece of filterpaper, using a small amount of mucilage or paste to fasten the paper firmly across the neck. Let it stand at room temperature and in ordinary daylight in a room free from acid or ammonia fumes for fourteen days, observing from day to day whether mould or any film on the surface forms, and whether any sediment forms on the walls or bottom

of the bottle.

7. Action on Steel Pens.-Immerse steel pens in the ink and leave them there for seven days. Remove the pens each day, clean them and note whether the metal appears corroded; also whether the ink has become thick.

8. Streak Tests.-Procure a supply of uniform good quality white all rag writing paper in sheets 265 × 200 mm. Stretch the paper on a smooth board inclined at an angle of 45° and let about o'6 cc. of the ink flow from a tube held vertically near the top edge of the paper. For this

Bulletin No. 109, Revised, U.S. Department of Agriculture, Bureau of Chemistry,

Water; 95 per cent alcohol; 90 volumes of water and 10 volumes of ammonium hydroxide (o'90 sp. gr.); 90 volumes of 95 per cent alcohol and to volumes of ammonium hydroxide (o'90 sp. gr.); 2 per cent hydrochloric acid; 2 per cent sodium hydroxide; bleaching powder solution, N/200 available chlorine.

The tests used are relative, and it is well to have a standard ink for comparison. Such a standard may be prepared by the following formula:-234 gims. of pure dry tannic acid; 77 grms. of pure crystallised gallic acid; 300 grms. of pure crystallised ferrous sulphate; 100 grms. of gum-arabic; dilute hydrochloric acid in sufficient amount to contain 2.5 grms. of hydrochloric acid (25 grms. dilute hydrochloric acid U.S.P.), and 10 grm. of crystallised carbolic acid.

All of these chemicals should be of U.S.P. quality, and in addition the purity of the tannin should be determined by the hide powder method (U.S. Dept. Agr., Bureau of Chemistry, Bull. 107, Revised, p. 36).

Dissolve the tannin and gallic acid together in about 50 cc. of warm water, dissolve the ferrous sulphate in about 150 cc. of cold water, dissolve the gum-arabic in about 150 cc. of warm water. Allow the warm solutions to cool, add the hydrochloric acid to the ferrous sulphate, and immediately mix all the solutions and make up with distilled water to 1000 CC. Mix thoroughly and allow to stand for at least four days at room temperature. Without shaking the bottle draw out the ink to be used in making comparisons. This standard ink will not be of a good colour, but will make a dirty grey-green mark which will finally turn black. It may be coloured to match the ink under examination by addition of a small amount of soluble dyes.

11. Rating.-The rating of a number of samples of ink is entirely relative, and any system may be adopted. The exposure to sunlight is, of course, the most important test, and the following scheme answers very well for record inks. Rate the standard ink as follows:

NEWS

Other record inks are given values above or below the figures for the standard ink, as the judgment of the analyst may indicate, so the total for a very good ink may be

Over 100.

Rate copying inks as record inks and make a separate rating on the copy, comparing one with another, and giving a weight of 50 per cent to clearness and depth of copy, and 50 per cent to resistance to reagents and sunlight. For further information consult Lunge ("Chemisch-Technische Untersuchungs Methoden," iii. 762), Schluttig and Neumann ("Die Eisengallustinten "), Mitchell and Hepworth ("Inks, Composition and Manufacture "), and Munson ("The Examination of Writing Inks," Journ. Am. Chem. Soc., 1906, xxviii., 512). The chromate logwood inks and the vanadium inks are not permanent. Among the inks examined by Munson no sample with a specific gravity below 1'035 was permanent, and with one exception no sample containing less than o'60 per cent of iron. The exception, however, was a very permanent ink, in spite of the fact that it contained only 0.32 per cent of iron.

Cancelling Inks having an Oil Base.

The work on Cancelling Inks is a revision of the methods previously issued as Circular 12 of this Bureau.

The following methods have been devised for the purpose of ascertaining the suitability of cancelling inks for the use of the Post-Office Department. Many of these methods will be found of assistance in passing upon the quality of stamping inks for miscellaneous uses. It is important that the ink used by the Post-Office Department for post-marking possess in the highest possible degree certain properties. The ink, first of all, must produce an indelible cancellation; that is, it must be relatively indelible as compared with the ink used for printing the postage stamps. The postmark made with the ink must dry quickly in order that the mail matter may be handled immediately without any blurring or smearing of the postmark. Both this property and the property of indelibility involve the question of the rate at which the ink penetrates or is absorbed by the fibre of the paper. A satisfactory ink does not harden or form a crust on the ink pad on exposure to the air. There must be no deposition of solid matter on the bottom of the vessel in which the ink is stored, and the pigments, on which the indelibility of the ink depends, if insoluble, must not settle out in such a way as to make it possible to pour off from the top of the container a portion of the ink which contains little or none of the insoluble pigment or pigments. The following methods have been found of value for the purpose of ascertaining the quality of a given sample of ink as well as the appropriateness of certain materials used for the manufacture of cancelling inks.

1. Preparation and Care of the Sample.-Since cancelling inks contain more or less insoluble and volatile matter, special attention must be given to the preparation and care of the sample. It must be carefully mixed by shaking before each portion is removed for analysis, and the container must be left open no more than is absolutely necessary for the removal of portions of the ink.

2. Determination of Matter Volatile at Ordinary Temperatures. Place a carefully weighed quantity (between 5 and 5.2 grms.) of the ink in a flat-bottomed aluminium dish 102 mm. (4 inches) in diameter. Distribute the ink completely over the surface of the bottom of the dish by gently tilting the same. This quantity of ink should be sufficient to completely cover the bottom of the dish. Place the dish on a horizontal shelf or table where air will have free access to it and where it will be screened in such a way that no dust can fall into it. Re-weigh the dish at the end of eighteen hours, twenty-four hours, two days, three days, four days, five days, six days, seven days, fourteen days, twenty-one days, and twenty-eight days. Calculate the total percentage loss of weight at the end of each period of drying. The loss of weight should be gradual and should not exceed 15 per cent during the first seven days, nor 25 per cent during twenty-eight days. This test shows the absence of highly volatile ingredients

and the absence of an excess of matter volatile at the ordinary room temperature. The constituents of a cancelling ink should be such that the volatile matter will not exceed the above limits when the ink is exposed under the conditions named to a summer temperature of 80° F. and upward.

3. Determination of Relative Penetrating Power.(a)Apparatus.-(a) Homœopathic shell vials about 8 cm. long and 2-2.5 cm. in diameter. (b) Strips of white blotting. paper, which for a given series of determinations should be cut from the same sheet and of exactly the same dimensions. A convenient size is 12 mm. wide and 25 cm. long. (c) A pair of dividers with arms 15 cm. long or longer. | (d) A millimetre rule.

(b) Determination.-Place approximately 5 cc. of the ink or other material to be tested in one of the "shell vials" described, and if several samples are to be tested arrange the vials in a row. Place 5 cc. portions of distilled water in each of two of the vials, and put one of the vials containing water at each end of the row of vials containing samples to be tested. Proceeding from left to right, insert a strip of blotting-paper in each of the vials, recording the exact time the paper was placed in each vial. The blottingpaper should maintain a nearly upright position. liquids gradually ascend the strips by capillarity; the strips, however, should be in such a position that the liquid does not ascend by capillarity between the edges of the strips and the sides of the vials.

The

At the expiration of exactly fifteen minutes from the time each strip is inserted in the vial, measure the height to which the liquid has ascended the strip of paper by means of a pair of dividers and record the distance in millimetres. Make a second set of readings at the end of forty-five minutes.

100.

After all of the measurements have been recorded reduce the results to the terms of the penetrating power of distilled water, taking the penetrating power of distilled water as This is accomplished by dividing each result by the average of the results obtained for the distilled water contained in the vials and multiplying the quotient by 100. Ten samples may conveniently be tested at one time by working as described. The method gives good comparative results, and has been applied not only to cancelling and other stamping inks, but to the liquids used for the manufacture of these inks.

In observing the penetrating power of a given sample of ink it is important to remember that the value of a cancelling or stamping ink depends upon its power to penetrate the paper during the first minute or fraction of a minute following its application to the paper. It is well, however, to keep the tests under observation for several hours, as information can thus be obtained in regard to the extent to which the colouring matter contained in the ink follows the liquid base of the ink as it passes through the paper. In some cases the colouring matters keep pace with the liquid portions of the ink; in others an uncoloured band at the top of the portion of the paper which is wet with the ink shows that the colouring matter does not proceed through the paper as rapidly as the base of the ink. This may or may not be an undesirable result. If the colourless band is due to a difference in the rate of penetration, it is undesirable. If it shows that the dye contained in the ink has an affinity for the fibres of the paper, it is evidence of a valuable quality.

Additional information can be obtained from the penetration test by removing the strips of paper from the vials, cutting off the part of the paper which has actually been immersed in the ink, and treating the upper part successively with petroleum, ether, alcohol, and other solvents for removal of the constituents of the ink soluble in these liquids. The extent to which the dye or dyes contained in the ink resist the action of these solvents and the extent to which the lampblack has passed up the strip of blottingpaper are indices of the quality of the ink.

An examination of the strips with the microscope will give valuable information regarding the rise of carbon in

the paper and the affinity of the dye for the fibre of the paper. With many inks the carbon will not rise above the surface of the liquid, while with others it penetrates the paper to the same height as the dye. With this class of inks it is important that the base of the ink have the power to carry the carbon well into the fibres of the paper.

sugar has been thus decomposed without the help either of ferments or chemical agents.

Aluminium Nitride. - Daffy Wolk. — Aluminium absorbs nitrogen at 820-850°. Below 700° the absorption is imperceptible. At 1000° it is rapid, while at 1100° dissociation occurs, and no definite product is obtained. The nitride which the author has prepared contains 33.6 per cent of nitrogen (34'06 for Al2N3). It is a grey amorphous mass, which is more easily decomposed by water the lower the temperature at which it was formed. Ammonia has no specific action on aluminium.

Decomposition of Water-vapour by the Brush

CHEMICAL

(To be continued).

SOURCES.

Comptes Rendus Hebdomadaires des Séances de l'Academie des Sciences. Vol. cli., No. 4, July 25, 1910. Colour Assumed by Colourless Solutions of Coloured Substances when they Separate from Colourless Solvents.-D. Gernez.- Mercuric iodide which in its stable form is a magnificent red below 126° becomes yellow at higher temperatures, and it separates in the yellow variety, which is unstable below 126°, from its solutions even at low temperatures. Colourless solutions of mercuric iodide in paraffin, menthol, &c., when heated to 100° and then suddenly cooled, yield the yellow iodide, which changes colour, becoming orange and finally red.

Racemic Liquid Compounds.-A. Ladenburg.-The author has studied the fusion curves of inactive pipecolin

containing varying amounts of d- and l-pipecolin. There is a eutectic point at 6:5° in a mixture containing 35 per cent of l-pipecolin, and the melting-point of racemic pipecolin (50 per cent d- and 5 per cent l-pipecolin) is -5°.

Place of Ultimate Rays in Spectral Series.-A. de Gramont. Certain series of spectral rays occur, such that their wave-lengths are the terms of a series which may be calculated by formulæ containing two or three terms, of which one is a constant. The constants and the factors of the different terms are periodic functions of the atomic weights. Each of the series forms a group having common characteristics. The author has now studied the ultimate rays to see whether they fit into these series. For substances which possess a principal series the ultimate rays always belong to it. With substances for which no principal series has been detected the ultimate rays do not belong to the secondary series, but a characteristic doublet has been detected and considered as the first term of the principal series the following terms of which are still unknown.

Effect of Temperature and Pressure on Cyanogen. -E. Briner and A. Wroczynski. - High pressures induce the formation of para-cyanogen from cyanogen and also cause the decomposition of cyanogen into its elements. To produce an appreciable amount of para-cyanogen at the ordinary pressure the temperature must be raised to 310°.

Action of Ultra-violet Rays on some Carbohydrates. -Henri Bierry, Victor Henri, and Albert Ranc.-The authors have investigated the action of the ultra-violet rays on the sugars which generate certain polyoses (eg, saccharose, gentianose, raffinose, &c.). d Fructose undergoes a deep-seated decomposition, yielding formic aldehyde and carbon monoxide. This is the first case in which this

C6H5 50 C2H5

BrMg one atom of hydrogen then migrates from the one aliphatic radicle to the other, yielding a saturated and an ethylenic hydrocarbon.

Constitution of Vicianose.-Gabriel Bertrand and G. Weisweiller. The hydrolysis of vicianose occurs according to the equation :—

C11H20010+ H2O = C6H12O6+C5H1005 d-glucose l-arabinose. Vicianose is thus a disaccharide formed by the union of a molecule of d-glucose with a molecule of l-arabinose.

Second

MISCELLANEOUS.

Hygiene.-The above Congress meets in Brussels from International Congress of Alimentary October 4 to 8, 1910. The following is the Provisional Programme :

Tuesday, October 4-10 a.m.: General Meeting in the

"Palais des Fetes" of the Universal Exhibition. Lantern Lecture by M. Dastre, Professor à la Faculte des Sciences de Paris et Membre de l'Institut; Subject "The Ultra-violet Rays and their Application to Alimentary Hygiene." 2 p.m. Meetings of the Sections in the Palais des Fetes." 5 p.m.: Lunch at "Le Chien Vert" (in the Exhibition). Wednesday, October 5.-10 a.m. and 2 p.m.: Meetings of Sections. 4 p.m. Lecture by M. Paterno, VicePresident of the Italian Senate, Professor of the University of Rome; Subject-"The Chemical Sciences." 7 p.m. Banquet at the "Tavern Royale," Rue Thursday, October 6.-10 a.m. and 2 p.m.: Meetings of d'Arenberg. Sections. 2 p.m. : Visits of Sections to the Exhibition. 4 p.m. Lecture by M. Bordet, Director of the Pasteur Institute, Brussels; Subject-"Hygiene and Bac teriology."

Friday, October 7.-10 a.m. and 2 p.m.: Meetings of Sections. 7 p.m.: Gala Performance at the Theatre Royale de la Monnaie.

Saturday, October 8.-Morning: Visits to the Exhibition,

to the Colonial Museum, and to the "Institut au Parc Leopold."

Members and Associates (subscription, 20 francs and To francs respectively) are admitted free to the Universal Exhibition during the time of the Congress. Special railway facilities have been arranged. Further information may be obtained of the Hon. Sec., CECIL H. CRIBB, 136, Shaftesbury Avenue, London, W.