NEWS They state that "comparatively thick copper wire and sheet, and even thin platinum wire, are easily melted and hard glass easily worked in its flame." Another factor that may have contributed to the difference in temperature noted in the two laboratories is the surface condition of the platinum crucible. Constam, in a paper (Journ. fur Gasbel., 1909, October 9, p. 889) communicated to the Seventh International Congress of Applied Chemistry, mentions "that the slower rise and the lower final temperature in dull platinum crucibles caused the yield of coke in them to be greater than in polished platinum crucibles." As the crucibles used in all the experiments at the Pittsburg laboratory were very dull and tarnished in appearance, it was decided to polish them and then run some determinations to check Constam's conclusions. The results are given in Table IX. TABLE IX.-Comparison of Volatile Matter produced in the same Crucible before and after Polishing. Per cent volatile. Difference. 0'7 was kept passing through during the determination; the heat treatment was exactly the same as in the official method. Both retort and crucible tests give results somewhat lower than the official method, although not materially. Summary. The results of these experiments may be briefly summarised as follows: Two laboratories are likely to vary 2 per cent in volatile matter, both using the official method. The percentage of volatile matter obtained from the same sample of coal varies with the temperature and rate of heating. This is not sufficiently defined by height of flame. Temperatures ranging from 760° C. to 890° C. may be attained with a 20 cm. natural gas flame, when the gas pressure is varied from 1 to 13 inches of water; variations of 2 per cent volatile matter are thus produced. Difference in type and size of burner influence results from 0-3 to 15 per cent. Polished crucibles become hotter and yield about I per cent more volatile matter than dull grey ones. Laboratories using natural gas are apt to get results on volatile matter that are considerably lower than those using coal-gas, unless the following precautions are observed: I. Gas should be supplied to the burner at a pressure of not less than 10 inches of water. 2. Natural gas burners admitting an ample supply of air should be used. 3. Gas and air should be regulated so that a flame with a short, well-defined inner cone is produced. 4. The crucibles should be supported on platinum triangles and kept in well-polished condition. Coal No. 45 SOME (b) Coke weighed. (c) Gradual heat. TECHNICAL METHODS OF TESTING INCLUDING PAINTS AND PAINT MATERIALS, INKS, By PERCY H. WALKER. (Continued from p. 82). PAINTS (continued). Coloured Pigments. 1. Yellow, Orange, and Red Pigments.-The most important yellow pigment is chrome yellow, which varies in shade from a light lemon yellow to a deep orange. The lighter shades generally contain lead sulphate as well as lead chromate, while the deep orange contains some basic lead chromate. Pure chrome yellow should contain only lead chromate, lead sulphate, and possibly some basic lead in the darker shades. (Lead sulphate may be replaced by other insoluble lead compounds. A chrome yellow should be considered adulterated if it contains anything besides insoluble lead compounds). Zinc yellow is zinc potassium chromate of a composition approximating the following formula: (ZnCrO4)3K2Cr2O7. (a) Chrome Yellow.-(1) Moisture.-Dry 2 grms. for two hours at 105° C. (2) Insoluble Impurities.-Treat 1 grm. with 20 cc. of strong hydrochloric acid, cover and heat on a steam-bath for fifteen minutes, add 100 cc. of hot water, (d) 30-grm. platinum crucible heat treatment as in boil (the solution should be complete), filter, wash, ignite, Official Method. In tests Nos. I to 6 inclusive, a sample of Pocahontas coal was subjected to destructive distillation in an iron retort, made from a piece of 1-inch gas-pipe, capped at one end and tubulated at the other. The retort was heated by means of a train of Bunsen burners to a bright red-heat in a furnace of asbestos board. A 20-grm. charge was used. Tests Nos. 7 to 9 inclusive were made in a 30-grm. platinum crucible with a tubulated cover; carbon dioxide and weigh the insoluble impurities. (3) Lead.-Evaporate the filtrate from the insoluble to about 2 cc., but not to dryness, add 100 cc. of 95 per cent alcohol, stir, allow to stand for one hour, cool in ice-water, filter on a Gooch crucible, wash with 95 per cent alcohol, dry for one hour at 110° C., cool, and weigh as lead chloride. Add 0.0085 grm. to the weight of the lead chloride to correct for its solubility in alcohol. Multiply the result thus obtained by 0'74478 to obtain the amount of lead present. (4) Chromium. * Bulletin No. 109, Revised, U.S. Department of Agriculture, Bureau of Chemistry. are pure or adulterated only with substances insoluble in -Evaporate the filtrate from the lead chloride determina- | The preceding methods will serve only for samples which tion to dryness on a steam-bath to expel the alcohol, add about 5 cc. of hydrochloric acid, then about 50 cc. of water, and warm till the solution is complete. Cool, transfer to a volumetric flask, and make up to a definite volume. To an aliquot add sodium peroxide in sufficient amount to render the solution alkaline and to oxidise the chromium to chromate, boil until all of the hydrogen peroxide is driven off, cool, make acid with sulphuric acid, add a measured excess of standard ferrous sulphate, and titrate the excess of iron with standard potassium dichromate. (5) Sulphate. In another aliquot of the filtrate from the lead chloride determination, determine the sulphate in the ordinary way by precipitation and weigh as barium sulphate. (Some chromes contain barium phosphate instead of lead sulphate, in which case test for phosphoric acid. Or barium sulphate, calcium sulphate, &c., may replace lead sulphate. Lead citrate is also sometimes present instead of lead sulphate). (6) Treatment in the Presence of Soluble Impurities.-If the sample contains no soluble impurities, the preceding method will give a complete analysis. When the qualitative test shows calcium it may be necessary to make the analysis in a somewhat different manner, for gypsum would by this treatment be precipitated with the lead chloride and render the determination worthless. In such a case dissolve and separate the insoluble as above. Dilute the filtrate from the insoluble to 400 cc., cool, pass in a rapid stream of hydrogen sulphide until all of the lead is precipitated as lead sulphide, filter, wash with water containing some hydrogen sulphide, dissolve the lead sulphide in dilute nitric acid (hot), add an excess of sulphuric acid, heat to fumes, and complete the determination of lead as sulphate in the usual way. In the presence of chromium the solution must be very dilute and the hydrogen sulphide passed in rapidly to get a good separation of lead as sulphide. Transfer the filtrate from the lead sulphide to a 500 cc. flask, add ammonium hydroxide until it is slightly alkaline, pass in hydrogen sulphide until all of the zinc present is precipitated (in case no zinc is present the addition of hydrogen sulphide is unnecessary); make up to volume, mix, allow to settle, draw off aliquots of the clear liquid, and determine the calcium (and, if necessary, the magnesium) in the usual way. All the zinc and chromium will still be in the 500 cc. flask; dissolve in hydrochloric acid, make up to the mark, mix, take out an aliquot, and determine the zinc volumetrically by the ferrocyanide method as described under lead zinc whites. In another aliquot determine chromium as already described. Sulphate can be determined by dissolving another portion in hydrochloric acid, filtering from it the insoluble, and precipitating with barium chloride from the dilute hot filtrate; if the solution is kept dilute and hot, the barium sulphate precipitate will not be contaminated by lead. (b) Zinc Yellow.-(1) Moisture.-Dry 2 grms. for two hours at 105° C. (2) Insoluble Impurities.-To 1 grm. of the dry pigment add 25 cc. of strong ammonium hydroxide, stir well, and dilute to about 100 cc. with water, stir frequently for about thirty minutes, carefully breaking up all lumps, but do not heat. Filter and wash with dilute ammonium hydroxide and then with water, dry residue at 105° C. to constant weight, and weigh, then ignite and weigh again. If desired, dissolve the residue in hydrochloric acid and analyse in the usual manner. (3) Soluble Zinc, Chromium, and Potassium.-Heat the filtrate from the determination of insoluble impurities to boiling in a graduated flask, pass in hydrogen sulphide until all of the chromate is reduced and the zinc is precipitated as zinc sulphide and chromium as chromium hydroxide. Fill to the mark, mix, allow to settle, draw out an aliquot of the clear liquid, and determine alkalis by adding sulphuric acid, evaporating to dryness, igniting, and weighing as mixed sulphates. If desired, potassium may be determined as potassium platinic chloride (K2PtCl6). Add hydrochloric acid to the residue in the flask and determine zinc and chromium as in chrome yellow. (4) Impure Samples.— | On (d) Vermilion.-True vermilion, or, as it is generally called, English vermilion, is sulphide of mercury. account of its cost it is rarely used in paints, and is liable to gross adulteration. It should show no bleeding on boiling with alcohol and water and no free sulphur by extraction with carbon disulphide. A small quantity mixed with five or six times its weight of dry sodium carbonate and heated in a tube should show globules of mercury on the cooler portion of the tube. The best test for purity is the ash, which should be not more than one-half of 1 per cent. Make the determination in a porcelain dish or crucible, using 2 grms. of the sample. Ash in a muffle or in a hood with a very good draft, as the mercury fumes are very poisonous. It is seldom necessary to make a determination of the mercury; but if this is required it may be determined by mixing o'2 grm. of the vermilion with o'r grm. of very fine iron filings, or better "iron by hydrogen." Mix in a porcelain crucible and cover with a layer 10 mm. thick of the iron filings, place the crucible in a hole in an asbestos sheet so that it goes about half way through, cover with a weighed, well-fitting, gold lid which is hollow at the top, fill this cavity with water, heat the crucible for fifteen minutes with a small flame, keep the cover filled with water, cool, remove the cover, dry for three minutes at 100° C., and thirty minutes in a desiccator, and weigh. The increase in weight is due to mercury. The mercury can be driven off from the gold by heating to about 450° C. A silver lid may be used, but gold is much better. Another method is to place in the closed end of a combustion tube, 45 cm. long and 10 to 15 mm. in diameter, a layer of 25 to 50 mm. of roughly pulverised magnesite, then a mixture of 10 to 15 grms. of the vermilion with four or five times its weight of lime, followed by 5 cm. of NEWS Determination of Red Colours in Organic Lake. Eosin. Changes to yellow; Changes to yellow; Little change; Source of colour. Scarlet (2R). on diluting. Purple; colour re- Purple; red on Darkened; lighter turning on dilut dark Purple; colour re- Little change. Sodium hy. Purplish; droxide (conc.) and alcohol brown on diluting. lime, and plug the tube with asbestos. Draw out the end of the tube and bend it over at an angle of about 60°. Tap the tube so as to make a channel along the top, and place it in a combustion furnace with the bent neck down, resting with its end a little below some water in a small flask or beaker. Heat first the lime layer, and carry the heat back to the mixture of lime and pigment. When all the mercury has been driven off, heat the magnesite, and the evolved carbon dioxide will drive out the last of the mercury vapours. Collect the mercury in a globule, wash, dry, and weigh. Genuine vermilion is at the present time little used in paints. Organic lakes are used for most of the brilliant red, scarlet, and vermilion shades. These organic colouring matters are sometimes precipitated on red lead, orange mineral, or zinc oxide; but as a usual thing the base is barytes, whiting, or china clay. Paranitraniline red, a compound of diazotised paranitraniline and beta-naphthol is largely employed; but a number of colours may be used. To test for red colours in such a lake the method from Hall may be of value ("The Chemistry of Paints and Paint Vehicles," p. 29), though other colours may be employed, which makes the accompanying table of only limited use. It is well also to try the action of reducing and oxidising agents such as stannous chloride, ferric chloride, &c. (see Zerr, Bestimmung von Teerfarbstoffen in Farblacken; also Schultz and Julius, "A Systematic Survey of the Organic Colouring Matters "). Paranitraniline red is soluble in chloroform. It is also well to try the solvent action on different reds of sodium carbonate, &c. The amount of organic pigment present in such reds is generally very small, and when it cannot be Slight reddish solution. Colour darker; reddish solution on diluting. CHEMICAL NOTICES FROM FOREIGN expressed. NOTE.-All degrees of temperature are Centigrade unless otherwise Zeitschrift fur Anorganische Chemie. Cryoscopic Determinations at Low Temperatures determined by ignition owing to the presence of lead, zinc, The degree of dissociation of a solvent seems to be inde Power of Adsorption of the Hydroxides of Silicon, Aluminium, and Iron.-Paul Rohland.-The power of adsorption of the hydroxides of silicon, aluminium, and iron, especially of silicon, is a property of talcs as well as of clays, though to a lesser degree. The talcs must be regarded as acid salts of metasilicic acid corresponding to the formula Mg2H2(SiO3)4. It was found that talcs adsorb the colloidal dissolved substances in blood, beer, starch, &c., also all dye-stuffs of complicated composition, coal-tar dyes, vegetable and animal dyes. Neither ions of weak acids, nor crystalloids, nor coloured substances of simple composition were adsorbed.—Zeit. Anorg. Chem., May 18. pendent of the temperature. Hydrocarbon derivatives, like carbon tetrachloride and chloroform, resemble benzene in their low dissociating power. Hydrocarbons give normal constants and molecular weights with all these substances, while alcohol gives smaller constants and correspondingly larger molecular weights. Ether, which on boiling gives the normal molecular weight for substances containing hydroxyl, also gave the normal constants on freezing at -117. In frozen chloroform the molecule of acetic ether shows no special tendency to associate. The molecular weight of iodine in its brown pyridine solution almost always corresponded to I2. In this case the production of an addition product could not be directly proved. The halogen hydrides are solvents which possess only a weak 108 Professorship of Chemistry in the University of Queensland. ་ CHEMICAL NEWS, dissociating power; in contrast to dissolved hydrocarbons | University to form the forefront of this educational and substances containing hydroxyl, e.g., thymol, alcohol, acetic acid, and benzoic acid, show a tendency towards association. The specific conductivity of the pure solvent increases from the hydrides of iodine, bromine, and chlorine, reaching the value o 2 × 10 -6 with the last. On dissolving substances which show cryoscopically an enlarging of the molecule the conductivity is many times increased. This appears to confirm the assumption of Steele, McIntosh, and Archibald that the conductivity depends upon the dissociation of complex molecules which result in the solution. Sulphuretted hydrogren is a solvent of very low dissociating power, and in its solution electrical conductivity cannot be proved. Hydrocarbons gave normal constants; substances containing OH moderate association. Benzophenone in dilute solution gave values which might point to a lowering of the number of molecules. Detection and Determination of very small Amounts of Silver.-G. Stafford Whitby.-All solutions of silver salts when heated with caustic soda and certain organic substances give a yellow or brown coloration even if only one part of silver is present in 25,000,000 parts. The organic substances are dextrin, gum arabic, cellulose, starch, and cane-sugar. Some drops of a fairly concentrated sugar solution are added to 50 cc. of the solution, the beaker is heated for two minutes on a water-bath, six drops of a normal solution of caustic soda are added, and it is again heated for twenty to thirty seconds. The colour of the solution is then compared with that of a solution containing a known amount of silver. Ammonia must not be present, but the other metals investigated did not affect the coloration, which is due to the presence of colloidal silver. Probably the caustic soda converts the silver into the hydroxide, which then reacts directly with the organic substances, a hydrogen ion of the organic molecule is split off and forms water with the hydroxyl ion of the silver hydroxide, while the silver, robbed of its ionic charge, goes into colloidal solution. Thermo-electricity of Alloys.-E. Rudolfi. - The author has determined the thermo-electric force of the following alloys in order to determine the relationship between the thermo-electric properties and the constitution of alloys: (1) Tin-cadmium, (2) zinc-tin, (3) zinc-cadmium, (4) tin-lead, (5) bismuth-cadmium, (6) lead-antimony, (7) gold-silver, (8) gold-copper, (9) copper-nickel, (10) platinumpalladium. The results of this investigation are given in a series of tables and diagrams, showing the thermoelectric forces at 150° and 100° towards both nickel and copper as a function of the concentration. The results show that (1) If the two components of a binary alloy do not mix in the crystalline condition, the relation of thermo-electric force to concentration is expressed by a straight line. (2) If the two components form an uninterrupted series of mixed crystals, and thus the solidified alloys consist of homogeneous crystals of the composition of the original mixture, the thermo-electric force curve is U-shaped. (3) If the alloy consists of mixed crystals only at certain concentrations the curve consists of two straight lines, the first sloping towards and the other away from the concentration axis. Similarly, if the two components form a compound the two straight lines forming the curve meet at the concentration corresponding to the compound; the curve is concave to the concentration axis. MISCELLANEOUS. Professorship of Chemistry in the University of Queensland.-Queensland was separated from New South Wales in December, 1859, and celebrated last December the completion of her first half century of independent existence within the Empire, and the Queenslanders have decided to commemorate this event by the foundation of a Under scientific advance. The Government (a Labour one) is THE CHEMICAL NEWS. kindly, and unselfish, he was one whom his friends loved and shrewd in nature, as became a Yorkshireman, yet gentle, VOL. CII., No. 2649. BRITISH ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE. SHEFFIELD, 1910. INAUGURAL ADDRESS OF THE PRESIDENT, The Rev. Prof. T. G. BONNEY, SC.D., LL.D., F.R.S. THIRTY-ONE years have passed since the British Association met in Sheffield, and the interval has been marked by exceptional progress. A town has become a city, the head of its municipality a Lord Mayor; its area has been enlarged by more than one-fifth; its population has increased from about 280,000 to 479,000. Communication has been facilitated by the construction of nearly thirtyeight miles of electric tramways for home service and of new railways, including alternative routes to Manchester and London. The supplies of electricity, gas, and water have more than kept pace with the wants of the city. The first was just being attempted in 1879; the second has now twenty-three times as many consumers as in those days; the story of the third has been told by one who knows it well ("History and Description of Sheffield Water Works," W. Terrey, 1908), so that it is enough for me to say your water supply cannot be surpassed for quantity and quality by any in the kingdom. Nor has Sheffield fallen behind other cities in its public buildings. In 1897 your handsome Town Hall was opened by the late Queen Victoria; the new Post Office, appropriately built and adorned with material from almost local sources, was inaugurated less than two months ago. The Mappin Art Gallery commemorates the munificence of those whose name it bears, and fosters that love of the beautiful which Ruskin sought to awaken by his generous gifts. Last, but not least, Sheffield has shown that it could not rest satisfied till its citizens could ascend from their own doors to the highest rung of the educational ladder. Firth College, named after its generous founder, was born in the year of our last visit; in 1897 it received a charter as the University College of Sheffield, and in the spring of 1905 was created a University, shortly after which its fine new buildings were opened by the late King; and last year its library, the generous gift of Dr. Edgar Allen, was inaugurated by his successor, when Prince of Wales. I must not now dwell on the great work which awaits this and other new universities. It is for them to prove that, so far from abstract thought being antagonistic to practical work, or scientific research to the labour of the factory or foundry, the one and the other can harmoniously co-operate in the advance of knowledge and the progress of civilisation. You often permit your President on these occasions to speak of a subject in which he takes a special interest, and I prefer thus trespassing on your kindness to attempting a general review of recent progress in science. I do not, however, propose, as you might naturally expect, to discuss some branch of petrology; though for this no place could be more appropriate than Sheffield, since it was the birthplace and the lifelong home of Henry Clifton Sorby, who may truly be called the father of that science. This title he won when, a little more than sixty years ago, he began to study the structure and mineral composition of rocks by examining thin sections of them under the microscope.* A rare combination of a singularly versatile and active intellect with accurate thought and sound judgment, His subsequent investigations into the microscopic structure of steel and other alloys of iron, in the manufacture of which your city holds a foremost place, have been extended by Mr. J. E. Stead and others, and they, besides being of great value to industrial progress, have thrown important sidelights on more than one dark place in petrology. of whom this city may well be proud. Sorby's name will be kept alive among you by the Professorship of Geology which he has endowed in your University; but, as the funds will not be available for some time, and as that science is so intimately connected with metallurgy, coalmining, and engineering, I venture to express a hope that some of your wealthier citizens will provide for the temporary deficiency, and thus worthily commemorate one so distinguished. But to return. I have not selected petrology as my subject, partly because I think that the great attention which its more minute details have of late received has tended to limit rather than to broaden our views, while for a survey of our present position it is enough to refer to the suggestive and comprehensive volume published last year by Mr. A. Harker ("The Natural History of Igneous Rocks," 1909); partly, also, because the discussion of any branch of petrology would involve so many technicalities that I fear it would be found tedious by a large majority of my audience. So I have preferred to discuss some questions relating to the effects of ice which had engaged my attention a dozen years before I attempted the study of rock slices. As much of my petrological work has been connected with mountain districts, it has been possible for me to carry on the latter without neglecting the former, and my study of ice work gradually led me from the highlands into the lowlands.* I purpose, then, to ask your attention this evening to some aspects of the glacial history of Western Europe. At no very distant geological epoch the climate in the northern part of the earth was much colder than it is at present. So it was also in the southern; but whether the two were contemporaneous is less certain. Still more doubtful are the extent and the work of the ice which was a consequence, and the origin of certain deposits on some northern lowlands, including those of our own islands, namely, whether they are the direct leavings of glaciers or were laid down beneath the sea by floating shore-ice and bergs. Much light will be thrown on this complex problem by endeavouring to ascertain what snow and ice have done in some region which, during the Glacial Epoch, was never submerged, and none better can be found for this purpose than the European Alps. At the present day one school of geologists, which of late years has rapidly increased in number, claims for glaciers a very large share in the sculpture of that chain, asserting that they have not only scooped out the marginal lakes, as Sir A. Ramsay maintained full half a century ago, but have also quarried lofty cliffs, excavated great cirques, and deepened parts of the larger Alpine valleys by something like two thousand feet. The other school, while admitting that a glacier, under special circumstances, may hollow out a tarn or small lake and modify the features of rock scenery, declares that its action is abrasive rather than erosive, and that the sculpture of ridges, crags, and valleys was mainly accomplished in pre glacial times by running water and the ordinary atmospheric agencies. In all controversies, as time goes on, hypotheses are apt to masquerade as facts, so that I shall endeavour this evening to disentangle the two, and call attention to those which may be safely used in drawing a conclusion. In certain mountain regions, especially those where strong limestones, granites, and other massive rocks are dominant, the valleys are often trench-like, with precipitous sides, having cirques or corries at their heads, and with rather wide and gently sloping floors, which occasionally descend in steps, the distance between these increasing with that from the watershed. Glaciers have unquestionably occupied many of these valleys, but of late years they have been supposed to have taken a large share in excavating them. In order to appreciate their action we must imagine the glens to be filled up and the district * May I add that hereafter a statement of facts without mention of an authority means that I am speaking from personal knowledge. |