\ dialysable part. The dialyser A communicates

Transcription

1 394 ABSTRACTS OF CHJMICAL PAPERS APPARATUS, ETC. Dialysing Apparatus. W. Kopaczewski. (Comptes rend., 1913, 156, )-The apparatus here shown may be used for the rapid dialysis of, e.g., enzymes into pure running water, the distillation of the water, and the concentration of the \ dialysable part. The dialyser A communicates by means of a two-way tap with the flask B, and with an exterior tube for taking samples of the water. The cork of the flask receives three tubes, one of which, T, communicates with a vacuum pump, the second with the dialyser, and the third (of tin) with the Soxhlet coolers C, which are connected together by means of a tin tube with two arms. In using the apparatus, the flask is charged with a quantity of water equal to that to which it is desired to bring the dialysable part of the liquid, The tap R is closed while a vacuum is created within the flask, after which the tap r is closed, the liquid then heated to boiling-point, and the dialysis carried out at a temperature of about 40" C. The apparatus may also be used for distillations in vacuo without previous dialysis. C. A. M. - International Standards for Coloured Fluids, and a Suggested Plan for such Standardisation. H. V. Amy. (Eighth Inter. Cong. App. Chem., 1912, Vol. 26, )-The author describes a method of colour-matching in which he

2 APPARATUS, ETC. 395 uses slightly acidulated (hydrochloric acid) solutions of (red) cobalt chloride (yellow) ferric chloride, and (blue) cupric sulphate, and blends these in any desired proportion. Starting with the possible combinations of the three colours that would make 12 C.C. when fractional portions of the C.C. are not employed, he has prepared a, set of eighty-eight blends, the tints of which, tabulated in the paper, range from the pink of cobalt to the blue of copper. He suggests a system of colour nomenclature based on the proportion of the solutions employed to make the tint, and reports at length on such '' Go-Fe-Cu " factors for solutions of caramel and cudbear. H. F. E. H. Apparatus for Gas Analysis. J. S. Agraz. (Zeitsch. anal. Chem., 1913, 52, )-The apparatus, which is made by the Vereinigte Fabriken fur Laboratoriumsbedarf in Berlin, was designed with a view to producing a single piece of apparatus which would serve for a variety of purposes. The illustration is selfexplanatory, except that the graduated tube is of 100 C.C. capacity, divided to 0.1 C.C. The dimensions given are fractions of a meter. G. C. J. Standardisation of Hydrometers. (rwemorandunz issued by the Director of the National Physical Laboratory, through Nature, 1913, 91, )-The Director has issued these notes with a view of eliciting opinions from makers and users, and of obtaining information from other countries, as there is at present much ambiguity as to tbe bases of standardisation of hydrometers graduated to read direct in degrees of sp. gr. The instruments are in all cases graduated for use in a liquid at a definite temperature, called the standard temperature of the instrument, and give the sp. gr. of this liquid at some definite temperature, which may or may not be the standard temperature of the instrument, referred to water at the same or some other temperature. The following three cases have arisen in practice, and it is desirable to fix upon one of them as the standard method : I. The water to which the sp. gr. is referred must be at the standard temperature of the instrument. 11. The water to which the sp. gr. is referred must be at some other definite temperature-e.g., 60" F., or possibly 4" C. Thus, if 85" F. is the standard temperature of the instrument, and 60" F. that of the water, the sp. gr. of the liquid at 85" F. is referred to water at 60" F The graduations are such as to give the value which would be found for the

3 396 ABSTRACTS OF CHEMICAL PAPERS sp. gr. of the liquid if it were cooled or heated to some other temperature and referred to water at that [or IV. some other] temperature. Thus, if the standard temperature of the instrument is 8 5O F., the instrument would be used at this temperature, but its graduations would be such as to give the sp. gr., which would be found for the liquid if cooled to 60" F., and referred to water at 60" F. Thus, using a sugar solution at 85" F. of sp. gr (Method I.), Method 11. would show , and Method Method I. has been the usual practice at Kew, 60" F. being the standard temperature ; No. 11. has the advantage that the reference temperature of the water is fixed, and gives results in agreement with the usual definition of sp. gr., which assumes a, fixed temperature for the water. H. F. E. H. Apparatus and Method for Determining Hydrogen Sulghide in Illuminating Gas. E. P. Harding and E. Johnson. (Eighth Inter. Cony. App. Chem., 1912, vol. 25, 673.)-The hydrogen sulphide is absorbed by a solution of cadmium chloride, liberated in a partial vacuum by hydrochloric acid, and titrated with standard iodine. This gives much more accurate results than Tutwiler's method, and agrees well with the gravimetric cadmium chloride method, which is the most accurate at present in use, but is not sufficientlyrapid for control work. The method described requires only from seven to ten minutes for a determination. 0. E. M. Apparatus fok the Determination of Dissolved Oxygen in Water. G. A. Soper. (Eighth Inter. Cony. App. Chem., 1912, vol. 26, 265.)--The method depends upon the measurement by permanganate of the oxidation caused in ferrous sulphate by the oxygen dissolved in water. A special form of apparatus is described which allows of the addition of the reagents (ferrous sulphate solution, sodium carbonate, and sulphuric acid) without exposing the water to the air. The bottle employed has a capacity of about 500 c.c., and has a long funnel-shaped top rising above the stopper, which is convex at the bottom, and when in place allows about 15 C.C. of liquid to stand in the funnel without overflowing. The capacity of the bottle is accurately gauged with the stopper in position. After filling the bottle with the water to be examined: and emptyiug the excess which rises in the funnel, 6 C.C. of the standard ferrous sulphate (144 grms. of sulphate and 15 C.C. concentrated sulphuric acid diluted to 3 litres) are delivered by a pipette to the bottom of the bottle. The stopper is replaced, and the water which rises in the funnel is gently poured off. Five C.C. of sodium carbonate solution (20 grms. crystals per 100 c.c.) are then poured into the funnel, and the stopper gently raised sufficiently to allow the heavy alkali to sink through the water to the bottom of the bottle. The stopper is lowered, the excess of water in the funnel is poured off, and the bottle shaken until the free oxygen is entirely absorbed. Ten C.C. of a 50 per cent. solution of sulphuric acid are then added in the same way, and the contents of the bottle are then turned out into an Erlenmeyer flask and titrated with permanganate. A blank determination is made whenever the water contains much organic matter or chlorine, the same process being followed, omitting, however, the addition of sodium carbonate. H. F. E. H.

4 APPARATUS, ETC. 397 Practical Field Method for the Determination of Dissolved Oxygen in Water. G. A. Soper and P. B. Parsons. (Eighth Inter. Cong. App. Chem., 1912, vd. 26, )-The method employed is similar to that in the preceding abstract, the sample being collected in a special form of apparatus, consisting of a separating funnel connected with an empty bottle of much larger capacity. The two are lowered together by a rope to any desired depth, the method of their connection being such that before the bottle can be filled the separating funnel has first to fill and empty itself several times. The separating funnel is then filled with the sample of water in the bottle, and the determination of the dissolved oxygen proceeded with as already described. A control sample which has been collected in a similar manner is also tested, but in this case the sulphuric acid is added first and the whole well shaken before introducing the ferrous sulphate, the acid reaction thus preventing the dissolved oxygen from acting on any of the ferrous salt. The difference between these results is the amount of ferrous salt acted on by the dissolved oxygen of the water. The form of separating funnel is substantially the same as that described by G. A. Letts (Appendix VII., Fifth Report of the Royal Commission on Sewage Disposal). The method is claimed to be especially suitable for field work and for tidal waters, or those containing nitrites. H. F. E. H. Methods and Apparatus used in Petroleum Testing. Part 11.: Viscosimetry. W. F. Higgins. (J. SOC. Chem. Ind., 1913,32, )-An abstract of a paper which described experiments made at the National Physical Laboratory, the chief object of which appears to have been to determine whether some simple expression could be found connecting true viscosities with the observed times of efflux from a Redwood viscosimeter, and to determine the order of accuracy which would attach to viscosities calculated by the use of such an expression. A comparison is also instituted between the results obtained by Redwood s and Engler s viscosinieters respectively. For a particular instrument of the Redwood type, and with times of efflux ranging from 40 to 2,000 seconds, it was found that the expression qt= (0*0026T---,)S gave numbers which differed from the true viscosities by less than +5 per cent., T being the time of efflux in seconds and 6 the density of the liquid at to C., the temperature at which the experiment is made and at which it is desired to know the true viscosity, qt. Ubbelohde (Tabellen xum Englerschen Viskosimeter, 1907) has arrived at the formula qt= ( T - $) 6 for calcula- ting viscosities from the observed times of efhx from Engler s viscosimeter, T in this case being the time of efflux, not of 50 c.c., as used with Redwood s instrument, but of the normal Engler quantity of 200 C.C. From these two equations the author has calculated the ratio TE/T, (time of efflux with Engler s viscosimeter / time of efflux with Redwood s viscosimeter) for nine values of T,. For values of T, from 5,000 down to 150, this ratio is almost a constant, As T, is further diminished, it increases slightly, becoming 1.83 when T, =; 40. Experimental comparison of an Engler and a Redwood instrument pointed to a ratio RE/R, = 1.8 k0.06. The same series of experiments showed that Ubbelohde s formula or tables, when used to

5 398 ABSTRACTS OF CHEMICAL PAPERS calculate viscosities from the results of experiments with the particular Engler viscosimeter possessed by the author, gave numbers mostly above the truth, the errors ranging from - 2 per cent. to + 8 per cent. G. C. J. Note by Abstractor.-The paper as printed contains two errors clearly attributable to its having been curtailed for purposes of publication, and the printed text would justify the assumption that the author was putting forward his formula, as applicable to all Redwood viscosirneters. This would conflict with the universal experience that the indications of these instruments may vary, and the printed discussion shows that the author is aware of such variations. The full text of the paper may be expected to appear in the next volume of Collected Researches of the National Physical Laboratory, or in some publication of the International Petroleum Commission, on whose behalf the experiments were made. Apparatus for Recovery of Evaporated Organic Solvents. W. Friese. (Pharm. Zentralhalle, 1913, 54, 419 ; through Chem. Zentralbl., 1913, I., 2015.)-The apparatus consists of an inverted double-walled, water-cooled funnel standing on three feet in a glass or metal circular trough, which fits over the evaporating basin, and has a side tube through which the recovered solvent runs off. It is made by Hugmshofl, Leipzig. 0, E. M. New Thermo-Regulator. E. Esclangon. (Conzptes rend,, 1913, 156, ) - This consists of a circular tube, A C B, closed at A and open at B. It revolves round its centre, 0, and at P carries a pulley, from which is suspended a weight, Q. The closed part of the tube, A, contains a saturating vapour, the nature of which..a depends upon the temperature which the apparatus is required to maintain. Thus for temperatures between 35 and 40 C. ether is a suitable substance, for temperatures about 55 C. acetone may be used, and for temperatures about 100 C. water is suitable. The centre of gravity of the apparatus is on the axis 0. Any alteration in the temperature will destroy the equilibrium and cause movements of the apparatus, the extent of which is controlled by the stops x and y. All that is required is to connect the movements with a heating or cooling apparatus. C. A. M. Comparison of Redwood s and Engler s Viscosimeters. W. Meissner. (Chem. Rev. Fett Ind., 1913, 20, )-Practical tests with standard instruments have been made, and the results compared with those calculated by means of the author s formulae (ANALYST, 1912, 37, 223). The relationship between the two

6 APPARATUS, ETC. 399 viscosimeters was found to vary with the temperature. The ratio between the Redwood values and the Engler degrees, which at 20" C. deviated from unity by amounts up to 11 per cent., was found to be about 6 per cent. greater at 50" C. than at 20" C. The explanation is that at 50" C. there are differences in temperature between the different parts of the apparatus, but it has not yet been ascertained in which type of viscosimeter the influence of these differences is the greater. C. A. M. Precision Viscosimeter for Measurement of Relative Viscosity and the Relative Viscosities of Water at O", 18", 25" and 50" C. E. W. Washburn and G. y. Williams. (J. Amer. Chem. SOC., 1913, 35, )-An improved viscosimeter of the Ostwald type is described. Its water-constant at a given temperature is not changed by cleaning with hot mixtures or by subjecting the viscosimeter to large variations of temperature. The water-constant (about 580 seconds at 25" C.) can be repeatedly reproduced to about 0.03 second under a given set of conditions. For effective pressures within the limits 130 and 300 mm. of water the deviations of the viscosimeter from Pouseuille's law is less than 0.03 per cent. The relatively large size and flattened shape of the lower bulb of the viscosimeter have the effect of reducing to negligible proportions any error due to small inequalities in the volume of liquid taken for the test. The normal charge with this instrument is 65 c.c., and an error of 1 C.C. in the measurement has so little effect on the mean head of liquid during the experimental interval that the time of flow varies no more than 0.05 per cent. A single instrument of this type can be used for a large temperature range, because its dimensions do not vary with varying temperature. The quartz viscosimeter is made by the Silica Syndicate, London. The relative viscosities of water at 0", 18O, 25", and 50' C. are given as qls/qo = , q25/qo = , and qso/q0 = , with a probable error of k 0.03 per cent. In obtaining these results the authors made use of chronometric apparatus permitting periods of time up to one hour to be recorded within 0.01 second, and of thermostatic appliances permitting temperature regulation to within a few thousandths of 1" C. These appliances are described in the paper, which also includes a statement of the reasons which determined the choice of the exact form and dimensions of the viscosimeter. G. C. J.