Metingen betreffende de toestandsvergelijking van Argon. Appointments Register" unless that society admits the ("Measurements Relating to the Equation of Condition evening students they teach on the same terms as day for Argon "). By C. A. CROMMELIN. Leiden: Eduard students.-I am, &c., ERNEST A. LEWIS. Ijdo. 1910. THIS book contains a critical study of the application of van der Waals' equation to argon, and the author has thoroughly summarised the literature of the subject. The preparation and purification of argon for the purposes of taking the observations are carefully explained in detail, and a complete list is given of the isotherms from -150 to 20°. Its vapour tension and critical temperature and pressure are also discussed, and the critical density is calculated. The book contains plates showing the apparatus used in the preparation of the gas and also the sotherms, and gives a useful summary of the determination of the physical constants of argon. CORRESPONDENCE. THE MOLECULAR VOLUMES OF SOLIDS. To the Editor of the Chemical News. SIR,-In my paper on the above subject (CHEMICAL NEWS, 1910, ci., 172), I noted on theoretical grounds that telluric acid was quite exceptional in its molecular volume. My forecast has now been practically confirmed by H. B. Baker and G. H. J. Adlam (Proc. Chem. Soc., 1911, xxvii., 17), who find that telluric acid always contains an excess of water even when dried for six months in a vacuum. This, of course, would lower its density and therefore throw up its molecular volume so that it refused to conform to the hypothesis I submitted.-I am, &c., H. H. STEPHENSON. CHEMICAL QUALIFICATIONS. To the Editor of the Chemical News. SIR, I should like to point out to employers of analytical chemists that the examinations for the degrees of B.Sc. in chemistry and metallurgy of the various Universities, also the higher examinations of the Board of Education in chemistry and metallurgy, are evidence of high qualifications and training in chemistry and metallurgy. The Board of Education examinations and the degrees of the University of London are the only examinations open to students of evening classes at the Technical Schools. The higher Board of Education examinations in chemistry and metallurgy, both theory and practical, are essentially practical and a thorough test of efficiency; personally, I should advise all students to take them in addition to any other examinations they may be preparing for. Many employers take far more notice of these certicates than degrees and similar examinations. I would point out that membership of a scientific society does not confer any right to the title " professional chemist," "duly qualified chemist," or any similar title; all it confers is a right to use certain initials, which, in recent years, have been mainly given for passing examinations. I do not say anything against these examinations; my experience with assistants who have passed them has been very satisfactory. The point I wish to emphasise is that there are other highly qualifying examinations which do not carry any right to use any initials. In consequence of the continued hostility shown to evening classes in certain quarters it appears to be necessary to point out to gentlemen holding official positions as teachers in evening classes at Technical Schools, that it is their duty to the ratepayers who employ them, and to the students who have to rely upon their teaching, to do their best to find positions in laboratories and works for their students, and to use all means in their power to press forward the fact that the examinations they prepare students for are qualifications; and it is no part of their duty to support, in any way, any society which has an OBITUARY. PROFESSOR JOhn attfield, f.r.s. WITH regret we record the death on Saturday last of Professor Attfield, at the age of seventy-five. The deceased had occupied the Professorship of Chemistry to the Pharmaceutical Society for thirty-four years. Next week we hope to give an account of some of the work performed by Prof. Attfield in the domain of Pharmacy and Chemistry, and of researches to which he had devoted considerable attention. CHEMICAL NOTICES FROM FOREIGN SOURCES. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. Vol. clin., No. 4, January 25, 1911. Transformation of a3-Phenyl Pentenic Acid into its yo-Isomer.-J. Bougault.-Fittig has shown that a8-pentenic acids are readily transformed into their syisomers by heating with alkalis, but the author finds that aß-phenyl pentenic acid yields no By-acid but the yo-acid C6H5-CH=CH-CH2-CH2-CO2H. The reaction appears to be complex, and some 3-oxy acid is formed, as well as an acid liquid which has not been identified. Acetylenic Pinacone.-Georges Dupont.-Acetylenic pinacone behaves towards hydracids like the corresponding saturated pinacone or like two molecules of tertiary alcohol, at any rate at low temperatures. Towards dehydrating agents it shows more resemblance to malonic pinacone, giving an ethylenic alcohol with dehydration of a methyl chain. But the dehydration is more complete, and the molecule of glycol behaves like two molecules of tertiary alcohol. Complete Destruction of Organic Matter for the Detection of Inorganic Poisons.-Pierre Breteau.-To 300 grms. of the organic substance 300 cc. of sulphuric acid (D=1·84) are added, and nitrous vapours are passed into the heated mixture. The organic matter gradually dissolves and chars, and finally the black liquid becomes quite clear and straw-coloured. It may then be concentrated in a platinum dish and examined for the presence of mineral poisons. MEETINGS FOR THE WEEK. MONDAY, 27th.-Royal Society of Arts, 8. "Applications of Electric THURSDAY, 30th.-Royal Institution, 3. "Surface Combustion and its Industrial Applications," by Prof. W. A. Bone, F.R.S. "Pre Royal Society. "Chemical Dynamics of Serum FRIDAY 31st.-Royal Institution, 9. "Travelling at High Speeds on the Surface of the Earth and Above it," by Prof. H. S. Hele-Shaw. SATURDAY, April 1st.-Royal Institution, 3. "Radiant Energy and Matter," by Prof. Sir J. J. Thomson, F.R.S. CHEMICAL NEWS, March 31, 1911 Studies of the Processes Operative in Solutions. It is known that, as a rule, alcohol retards chemical change, although there are cases in which it has an accelerating effect. In the first of these communications, it was shown that ethylic alcohol has a marked effect in retarding the hydrolysis of cane sugar, even when only a single molecular proportion is added to a weight-normal solution of chlorhydric acid and sugar, the value of K falling from 510 to 467. Caldwell, in discussing this result, has pointed out that: 145 being raised from 510 to 521 by the addition of a molecular proportion of the acid. Like the alcohols, the acids of the acetic series influence the rate of entry of water into the barley grain, water entering more rapidly with the acid from solutions of the higher acids; moreover, J. Loeb has found this relationship to hold good in the case of entry of acids into the echinoderm egg, as shown by the rate at which the eggs begin to develop. It is highly remarkable in the case of the monhydric alcohols and monobasic acids, that activity is greatest, however tested, in the case of the compounds which are least soluble in water and that their activity is in some way (inversely) proportional to their solubility. In order to determine the effect, in several cases of chemical change, of paraffinoid alcohols and acids, we have subjected cane sugar to the action of chlorhydric acid in presence of the various substances. In all cases, the solution used contained a single molecular proportion of hydrogen chloride and of the added substance, together with a quarter of a molecular proportion of sugar and either 50 or 80 molecular proportions of water. Hydrolysis was effected at 25°. The results with ethylic alcohol and acetic acid are in agreement with Caldwell's earlier observations. As we anticipated would be the case, methylic alcohol is less but propylic more effective than ethylic alcohol; butyric acid, in like manner, is more effective than acetic acid, in that it has a distinct depressant influence whilst acetic acid has a slight accelerating influence. The values arrived at are as follows: the Acetic Series on Hydrolytic Activity. Added substance, 50 molecular pro- 80 molecular proportions of water. K. "Alcohol may be pictured as acting in at least three ways:-(1) Mechanically, by its interposition between the acting substances; (2) as exercising a concentrating effect, such as the sugars exercise by combining with water; (3) as entering into association with the active agent, viz., bydrogen chloride, forming an 'alcoholate.' Of these, (1) and (3) would be unfavourable, whilst (2) would accelerate the change. There is every reason to suppose Effect of Alcohols of the Ethylic Series and of Acids of that all three influences are operative and that the concentrating effect of alcohol is more than counterbalanced by the extent to which it interferes mechanically and probably, more especially, by the formation of an alcoholate." Later observations lead us to think that cause (1) rather than cause (3) is mainly operative in retarding change. The experiments carried out by one of us in conjunction with Dr. Eyre, of which an account was given to the Royal Society of London on June 24th, 1909 (Proc. Roy. Soc., 1910, A, lxxxiv., 123), show that the diminution in solubility of sodium chloride and other haloids effected by alcohols varies, in the case of the alcohols of the methylic series, as the molecular weight increases, propylic alcohol being a more effective precipitant than ethylic and methylic, alcohol, and the former alcohol more effective than the latter. Subsequent observations show that isobutylic is considerably more effective than propylic alcohol. The same relationship is apparent on contrasting the effect alcohols have in reducing the molecular electrical conductivity of solutions of salts, a subject discussed in No. XVII of these communications. We have learnt recently from Professor Adrian J. Brown that observations on the rate at which water enters into the barley grain from alcoholic solutions also show that the rate of entry of water together with the alcohol is more rapid in the order given, in the case of propylic, butylic and amylic alcohols, than in that of the lower homologues, except that methylic appears to be more active than ethylic alcohol. Similar observations made by one of us and E. F. Armstrong on the rate at which the alcohols gain entry into leaves such as those of the cherry-laurel (Prunus laurocerasus) and the Japanese laurel (Aucuba japonica) show that the higher alcohols of the ethylic series are the more active. We have obtained evidence with these alcohols also, in quite another way, of an increase in activity as the series is ascended. In all these cases, as no acid is present, the effect would seem to be of a "mechanical” order; it cannot come under Caldwell's case (3). Caldwell has shown that acetic acid has a slight positive or "concentrating" effect equivalent to the withdrawal of one from about 55 molecules of water, the value of K I molecular proportion. NaCl NaCl + C3H7(OH).. 303'5 K. 580 549 295 358 The influence exercised by acetic acid would seem to be a true concentrating effect, as the specific hydrolytic activity of the acid is too slight to account for the effect it produces. It is to be supposed that the changing system is one. composed of the "hydrated" hydrolyte and the "hydrated" catalyst (the acid) and that such complex systems are formed reversibly. If hydrolysis take place only in a certain proportion of the systems, any interference with the formation of the systems would reduce the rate at which hydrolysis is effected. But a variety of influences must be at work, as glycerol is considerably less active than ethylic ́ alcohol in retarding change, although a larger molecule; moreover, the glucoses are apparently without influence. The nature of the influence exercised will be more fully discussed in a later communication. (NOTE. The communication of which this is the immediate sequel appears in the March issue of the Journal of the Chemical Society, together with Nos. 14 and 15. The withdrawal of the articles now published in this journal -this being the fourth-was rendered necessary solely by the refusal of my request that I might be allowed to qualify a noun by an adjective-the noun alcohol by adjectives such as methylic, etc. I have resented such arbitrary action on literary grounds as well as because it is an interference with the proper liberty of speech which must, I contend, be permitted to authors of communications to scientific societies. I may quote the following classic telegram received from the Editor on February 10th as an illustration of the condition to which we are reduced: "In view Committees letter cannot accept Methanol | etc. for methyl alcohol etc. must have your acceptance letter before publishing papers further reference Committee delays publication till March." This to a Fellow of over forty years standing who was an active member of the Geneva Conference on Nomenclature! The mind being occupied in various directions and oppressed by difficulties, in rendering an account of our work it is never easy to give correct expression to our thoughts; we are too often, through carelessness, guilty of using incorrect expressions-that an attempt should be made to impose their use is intolerable.-H. E. A.). ratio of ree sulphuric acid (sp. gr. 1-84) to total solution was not less than 1 to 6 nor more than 1 to 5. When the solutions contained more acid than the ratio of 1 to 5, the zinc sulphate which formed did not go into solution, and prevented the ready passage of the solution through the reductor. When the acid was present in amounts less than the ratio of 1 to 7, the reduction of the solution was incomplete, due to too slow action of the acid on the zinc. The reduction was complete in all cases when the ratio of free sulphuric acid to total solution was within the limits of 1 to 6 and 1 to 5." An extensive experience with the Jones reductor led us to adopt a simpler form of it for the reduction of uranium solutions. It is shown in the accompanying figure. The C THE VOLUMETRIC DETERMINATION OF URANIUM. By F. IBBOTSON, B.Sc., and S. G. CLARK. Of the few volumetric methods for the determination of uranium, the principal one depends upon the reduction of a uranyl solution, followed by a titration of the reduced solution with potassium permanganate. The reducing agent commonly employed is zinc, which is added in very large excess to the uranyl solution containing much free sulphuric acid, and the completion of the reduction is determined either by the thorough solution of the zinc, or by the time empirically specified for the reduction of a definite amount of uranium, or by the change of colour from the yellow of uranyl solutions to what is described by some observers as a clear chromium green and by others as the green of nickel solutions. The reductions are usually conducted in hot solutions, and in all cases it seems to be necessary that precautions should be taken to prevent the atmospheric oxidation of the reduced solution during the subsequent manipulations. In a paper on "The Quantitative Separation and Determination of Uranium " (Journ. Am. Chem. Soc., xxiii., No. 10; and CHEMICAL NEWS, lxxxiv., 224 et seq.), Kern, for example, used about 50 grms. of pure zinc in lumps for the reduction of from o'1 to 0.2 grm. of uranium. The reduction was carried on at the boiling-point of the solution, every four to five parts by volume of which contained one part of sulphuric acid. The zinc was allowed to dissolve completely, and the solution was then rapidly transferred to a flask containing a grm. of sodium carbonate, and titrated at once. observes that "the time required for the reduction of about o'i grm. of uranium by zinc is about one hour, for about o'2 grm. not less than one and a-half hours. The uranyl sulphate solution, at first yellow in colour, changes to light green, and finally to green with bluish tinge, having the appearance of a dilute solution of nickel chloride, which colour it retains even though the reduction be continued for as long as four hours." Kern Much time is saved as a rule if reductions with nascent hydrogen are conducted in a Jones reductor, which has become an almost indispensable tool in the equipment of analytical laboratories, more especially of those concerned primarily with the analysis of steel and steel-making alloys. The Jones reductor consists essentially of a column of finely divided amalgamated zinc contained in a tube through which the solution to be reduced is allowed to filter under suction into a flask. Blair ("The Chemical Analysis of Iron ") makes use of the reductor for the determination of phosphorus in steel, and it has been applied to the determination of vanadic acid by Gooch and Edgar (Am. Fourn. Sci., xxv., 233), by Edgar to the determination of molybdic and vanadic acids (Am. Journ. Sci., xxv., 332), and also to the determination of vanadium and iron in the presence of one another (Am. Journ. Sci., xxvi.). For the reduction of uranium solutions Kern recommends a longer reduct than usual, and makes use of a column of 20-mesh zinc about 45 cm. long, contained in a burette- the ordinary length is about 30 cm. He finds that "the most sat sfactory results were obtained when the B A length A c is about 22 cm., and A B, which is occupied by the zinc, is 15 cm.-the diameter is 2 cm. A filter-plate covered with a layer of ignited asbestos fibre is placed at A. The side opening of the flask is connected to an ordinary bottle for supplying the small amount of aspiration necessary. The zinc was amalgamated by shaking it in a flask with a solution of mercuric sulphate in 24 per cent sulphuric acid, the usual proportion being I grm. of metallic mercury for every 100 grms. of zinc. After washing several times with 2 per cent sulphuric acid, and finally with water, the zinc was transferred to the reductor-tube and kept permanently covered, when not in use, with water. About 120 grms. of 20 to 30-mesh zinc were required. In all the reductions made by us, 100 cc. of sulphuric acid of the strength specified in the appended results were first passed through the column of zinc, next the uranyl olution acidified to the same extent, then 100 cc. more CHEMICAL NEWS, March 31, 1911 Determination of Tin and Antimony in Soft Solder. acid, and finally 100 cc. of water. A blank determination on the reagents never showed more than o'r cc, of N/20 permanganate in the titration. Cold solutions were used throughout. The uranyl solution was prepared from Kahlbaum's acetate, and was carefully assayed gravimetrically by precipitation as phosphate; 50 cc. of the solution contained 0.2566 grm. of the metal, which requires theoretically a consumption of 42.77 cc. of N/20 permanganate in the titration of the reduced solution. The following figures are selected from a very large number of results obtained : In each of these tests the colour of the reduced solution was certainly not that of pure uranous solutions, but brownish green, and the greater the degree of reduction the greater the suppression of the clear green of pure uranous solutions. After aspirating a current of air through the reduced solutions for a minute or so, the brown tint was completely dispelled, and, on titrating, the lowest reading of the permanganate was 42.7 cc. and the highest 42.9, representing 0*2562 and 0.2574 grm. uranium respectively. The correct reading 42.8 cc. was given in the majority of the large number of tests made. 147 manipulations, a fact evidenced by the colour changes during the performance of these operations. The stability of cold uranous solutions having been established, the only factor which could determine this oxidation was evidently the temperature of the solutions. A further set of reductions was therefore made by heating the solutions as before, and, when a strong brown colour was developed, the flasks were rapidly cooled to ordinary temperature. In every case, after filtering and washing, and aspirating air for a minute, or even after allowing the solution to remain exposed to the air for twenty minutes, the readings of the permanganate were 42'7 or 42.8 cc. The volumetric determination of uranium can therefore be made in about fifteen minutes by the following process: -Pour the solution of uranyl sulphate containing from 2 to 5 per cent by volume of free sulphuric acid into a flask containing about 50 grms. of pure finely divided and amalgamated zinc (20 to 30-mesh) and heat until a dark brown colour is developed. Cool the flask rapidly under a stream of water, and then pour the cold solution through a small pulp-filter, wash with cold water, aspirate air for a minute through the filtrate, and titrate with permanganate. The zinc may be used for a dozen determinations at solution can be poured through the filter without carrying least before it requires further amalgamation. The reduced more than a few particles of the metal with it. Since uranyl solutions are not reduced by sulphurous acid, a mixture of ferric sulphate and uranyl sulphate can be assayed by first reducing the iron with sulphurous acid, titrating with permanganate, and then treating the titrated solution as above. Metallurgical Department, The University, Sheffield. ΙΟ It is evident from the above figures that the reduction of cold uranyl solutions to the uranous condition is more than completed during the short time (about five minutes) occupied by their passage through the column of zinc, but the results show varying degrees of reduction, no one of which corresponds to any definite chemical composition. It is further evident that cold uranous solutions are much more stable than is generally supposed, since the aspiration of air which in several experiments was continued at a brisk rate for twenty minutes, did not result in a measurable amount of oxidation. An attempt was made to carry the reduction to the condition corresponding to the formula U2(SO4)3, which would have involved 64.15 cc. of N/20permanganate in the titration. This was done by first passing the solution through the short reductor as above, and then passing the reduced solution through a much longer reductor into a receiver containing an excess of ferric alum so as to eliminate atmospheric oxidation. The titration figure was 50'2 cc., from which it is seen that zinc in sulphuric acid solution will not effect the reduction to U2(SO4)3, a conclusion also reached by Kern (loc. cit.). As already stated, cold solutions were used in the above experiments, but when, instead of passing the uranyl solutions through a reductor, they were brought into contact with a large excess of amalgamated zinc in an open vessel and the solutions were heated, it was at once obvious that a very rapid reduction took place, even in solutions of 2 per cent acid. In less than five minutes, that is, before the solutions reached boiling point, the change from yellow through the clear green to dark brown had taken place. After passing the hot solutions through a small filter to strain off tiny particles of zinc, and washing, the following extraordinary readings were obtained on titration with permanganate:-415 cc., 40·8, 41'1, 416, &c. Oxidation had thus taken place during the filtration and subsequent DETERMINATION OF TIN AND ANTIMONY IN SOFT SOLDER. By J. H. GOODWIN. THE following details for the rapid volumetric determination of tin and antimony in soft solder are adapted from A. H. Lowe's method (Journ. Am. Chem. Soc., xxix., 66). Antimony. On a counterpoised watch-glass weigh exactly 2 grms. of filings, which should be fine enough to pass a 30-mesh sieve. With a quill brush transfer the filings through a stemless funnel into a 300 cc. Jena Erlenmeyer flask. Add 5 grms. of KHSO4 crystals and 10 cc. of sulphuric acid, specific gravity 1.8. By means of corklined tongs or test-tube holder manipulate the flask over a bare Bunsen flame until most of the free acid is expelled and no sulphur remains on the walls of the flask nor in the liquid. Do not attempt to take to dryness. Place the hot flask on a piece of asbestos. The tin is now all a stannic and the antimony all an antimonous salt. When the flask cools sufficiently add 25 cc. of cold water and 5 cc. of hydrochloric acid, specific gravity 12 (P. H. Walker and H. A. Whitman also use less hydrochloric acid than A. H. Low, Fourn. Indust. and Eng. Chem., i., 519). Manipulate over a free flame for half a minute to complete the solution of the tin and antimony salts and to expel any sulphuric dioxide. Cool the flask under running water. Add 100 cc. of cold water, and titrate rapidly with N/20 potassium permanganate. From the volume of the latter required to give the first pink colour calculate the per cent of antimony. Dry to constant weight some highest purity sodium oxalate, made according to Sorensen, and use this to standardise the N/20 potassium permanganate solution. Tin.-Weigh exactly o‘2 grm. of the filings and transfer as before to a 300 cc. Jena Erlenmeyer flask. Add 5 cc. of 15 per cent sodium carbonate solution. Add 20 cc. of hot water. Add 25 cc. of hydrochloric acid, 12 specific gravity. Add drop of 5 per cent antimony chloride solution from a dropping bottle. This solution should be strongly acid with HCl. Close the flask with a 1-hole rubber stopper carrying a capillary U-tube of 1 mm. bore. The short arm of the U-tube should just reach through the stopper, while the long arm should almost reach the surface on which the flask stands. Place the flask on a hot plate where it will boil very slowly but not suck air back through the tube. The solder will dissolve in about fifteen minutes, leaving a small black precipitate of antimony. As soon as this occurs, and without interrupting the slow boiling, bring a test-tube of 15 per cent sodium carbonate solution under the U-tube. Carry to the sink and cool the flask under running water, allowing the carbonate solution to suck back into it. When cold, add 5 cc. of 15 per cent sodium carbonate solution and 5 cc. of cold fresh starch fiquor, and titrate immediately with N/20 iodine solution. From the volume of the latter required to give the first deep blue colour calculate the per cent of tin. Standardise the N/20 iodine solution by titrating in the same way o'I grim. portions of filings made from a stick of Kahlbaum's highest purity tin. This method can be used to advantage for soft solder containing o to 2 per cent of antimony, 30 to 60 per cent of tin, 40 to 70 per cent of lead, and not more than traces of any other metals. Duplicate determinations of tin and antimony can be made in one hour.-Journal of Industrial and Engineering Chemistry, iii., No. 1. METHODS OF ANALYSIS AND TESTS OF FATS 2. Moisture. The term "moisture," as here used, refers to the chemical substance "water" physically incorporated in the fats and fatty oils. Standard Method.—(Similar to that mentioned by Ubbelohde). 100 grms. of the sample are mixed with 100 cc. of xylene in a suitable distilling flask, and about 50 cc. slowly distilled off over a free flame. The distillate containing the water is collected in a tube 0.75 cm. diameter graduated in 1/10 cc., and the percentage of water read off directly from the volume of water contained in the tube. Correction is to be made for the solubility of water in xylene. Details to be supplied. (The boiling-point of xylene is 138° C.). 3. Suspended Impurities. Definition.-Suspended impurities in fats and fatty oils are those non-fatty solid substances physically incorporated therewith and insoluble in hot petroleum ether, such as particles of wood, coal, fibres, and mineral matter. They are determined by the standard method given below. Determination: Standard Method.-A sufficiently large sample to be representative should be weighed out and dried, or the residue from a moisture and volatile matter determination may be used. Usually from 5-20 grms. should be used. The sample is dried in a beaker over asbestos board, keeping the beaker in motion by hand to prevent sputtering. The sample is then dissolved in hot petroleum ether (boiling point 50-70° C.) by gentle boiling on a water-bath, filtered on a Gooch crucible or porous crucible, washed thoroughly with a boiling petroleum ether (boiling-point 50-70° C.), dried to constant weight, and weighed. 4. Free Fatty Acids. Preparing Neutral Alcohol.-Take commercial 95 per cent alcohol, add 50 grms. powdered caustic soda per litre, boil with reflux condenser for a period of six hours, allow THESE methods are proposed tentatively with the object to stand for twenty-four hours, and then distil. Alternate of inviting criticism and discussion). 1. Moisture and Volatile Matter. Weighing out Sample.-By the application of gentle heat soften, but do not meit, the sample, and emulsify thoroughly by means of a mechanical egg beater (or other suitable device). Of the thoroughly emulsified sample weigh out for the standard methods from 5 to 20 grmɛ. according to the method used from weighing bottle into a watch glass or shallow glass dish whose sides are not more than 1 cm. high. Standard Method No. 1, Moisture and Volatile Matter at 110° C.-A 5-10 grm. sample weighed out as above is heated in an oven held at a constant temperature of 110° C. until constant weight is attained. Constant weight is attained when successive weighing thirty minutes apart show a loss of not more than o'05 per cent. Standard Method No. 2, Moisture and Volatile Matter. -A 5-10 grm. sample weighed out as above is heated in a vacuum oven held at 50° C. under a pressure of not more than 30 mm. of mercury for four hours. (The tension of water vapour at 50° C. is 92 mm.). Routine Method, Moisture and Volatile Matter.-The sample weighed out in a glass or aluminium beaker as above is heated on a heavy asbestos board over burner or hot plate, the sample at no time being allowed to reach a temperature greater than 130° C. During the heating the beaker is rotated gently on the board by hand to avoid sputtering or too rapid evolution of moisture. The proper length of time of heating is judged by absence of condensation on a cold watch-glass held over the beaker, by the absence of rising bubbles of steam, by the absence of foam, or by other signs known to the operator. Cool in desiccator and weigh. Report loss as moisture. * American Chemical Society, method. Determination.-From 5-15 grms. of the sample are weighed into an Erlenmeyer flask (100 cc, capacity) and melted on the steam-bath, if solid at ordinary room temperature. Add 100 cc. of hot neutral alcohol. Titrate with N/2, N/4, or N/10 sodium hydrate, using phenolphthalein as indicator. Where the fat is known to have a mean molecular weight of 282 or thereabouts, that figure is to be used in calculating the percentage of free fatty acids. Report also the acid number: mgrms. KOH rerequired to neutralise I grm. The percentage of free fatty acids is to be calculated on the basis of sample freed from moisture and volatile matter. 5. Titre. Method Proposed by L. M. Tolman as follows (Bureau of Chemistry, Bulletin 107, revised):-"Weigh 75 grms. of fat into a metal dish, and saponity by using 60 cc. of 30 per cent sodium hydrate (36° Baumé caustic soda) and 75 cc. of 95 per cent by volume alcohol, or 120 cc. of water. Boil down to dryness, with constant stirring, to prevent scorching. This should be done over a very low flame or over an iron or asbestos plate. Dissolve the dry soap in a litre of boiling water, and if alcohol has been used boil for forty minutes in order to remove it, adding sufficient water to replace that lost in boiling. Add 100 cc. of 30 per cent sulphuric acid (25° Beaumé sulphuric acid) to free the fatty acids, and boil until they form a clear transparent layer. Collect the fatty acids in a small beaker, and place on the steam-bath until the water has settled, then decant them into a dry beaker, filter, using a hot-water funnel, and dry twenty minutes at 100° C. When dried, cool the fatty acids to 15° or 20° C. above the expected titre and transfer to the titre-tube, which is 25 mm. in diameter and 100 mm. in length (1 by 4 inches) and made of glass about mm. in thickness. This is |