ABSTRACTS OF CHEMICAL PAPERS. ABSTRACTS OF CHEMICAL PAPERS PUBLISHED IN BRITISH AND FOREIGN JOURNALS. Physical Chemistrg. Researches 0th the Spec$c Heck Demitits am1 Expamions of some Liquids. By C. MARIGNAC.* PARTI.-SPECIFICHEATS.The specific heat of aqueous solutions is estimated as follows. A large sized mercurial thermometer with a spirally coiled tube for a reservoir is heated in an oven to a few degrees above the point required. On being taken out it is brought near to the calorimeter in which it is immersed the instant the mercury in the stem has fallen to the desired point. The calorimeter contains the liquid the specific heat of whish is to be estimated and the quantity of liquid employed is regulated so that the intro-duction of the heated thermometer produces in every experiment sensibly the same elevation of temperature.Under like atmospheric conditions all exterior disturbing causes thus influence the temperature of the calorimeter to the same extent in every experiment and have no influence on the result. All corrections may therefore be dispensed with. To ensure these like conditions the experiments performed on each solution are made to alternate with the parallel experiments on water and are thus strictly comparable with these latter. The quan- tities of liquids used am inversely proportional to their specific heats. For saline solutions a silvered brass calorimeter is employed; for strongly acid liquids a thin glass vessel is substituted. The specific heat of more volatile liquids is estimated by enclosing them in a thin glass bulb containiiig a small bEt sensitive thermometer and employing this bulb instead of the large mercurial thermometer as the source of heat In these cases the calorimeter of course always contains the same amount of water and the quantity of liquid nsed in the bulb is so adjusted that it has always the same capacity for heat and therefore produces the same elevation in the temperature of the calorimeter.The experiments as in the previous case being compara- tive all corrections for loss by radiation &c. are here also dispensed with Different experiments made by the foregoing methods with one and the same liquid give extremely concordant results. In what follows C stands for the nioleculw heat of tlre various liquids employed 1% for the number of moiecules of wiiter to one molecule of the substance dissolved.SuZplmric acid H20.,SO + ndq.-The acid employed had been purified by dist,illation and brought to tho monohydrate by repeated * Phil. Mag. [4] xli 134. PHYSICAL CHEMISTRY. congelation. Experiments made by tlic first method lead to the follow-ing empiricai formula for the calculation of C :-334.8 2882 7262 C = 18%+ 8.58 +-__ + -. n rb2 TL3 The formula is inapplicable to solutions containing less than 5 mole- cules of water. The specific heat of the monohydrate was found to be 0.3315 for temperatures between 16" and 20". Some experiments made by the second methoh on mixtures with less than 5 molecules of water gave the following results for the specific heat between 20" and 56" :-Specific heat.Noleculsr hat. Monohydrate .................. 0.3363 33 With 1molecule of x-at;r ........ 0.4411 51.2 79 ?Y 77 3 ........ 0.5056 76-8 77 77 7) 5 ........ 0.5833 109.7 These results agree well with those of the first series and also confirm the curious fact established by Pfaund lei- that the first equivalent of water added to monohydrated sulphuric acid increases the molecular heat by a quantity precisely equal to that of the water added while fbr every further dilution there is a considerable loss of molecular heat. Sodium suZphate Na,O.SO + 1~ hq.-Experiments on solutions with 50 100 and 200 iimlccules or T>atcr respectively lead to the followine formula for C : " 4094 98000 C = 1%-16.34 + -~ TL I? -The formula becomes inaccurate in the case of weaker solutions.For solutions containing more than 200 molecules of water the specific heat is less than that of the water alone; the specific heat is always diminished by the addition of water. Sod~u~.lt-lLycl~,oge1L sulplintc %} Q.SO + ?L Aq.-The empirical for-mula for C is 1292 ll500 c = 18,b 4-11.65 + --5"L 2 A comparisonof the molecular heats of solutions of sdphate ofsodium bisulphate and of sulphuric acid of corresponding strengths shows that the molecular heat of bisulphate solutions is always above the mean of the molecular heats of the neutral sulphate and of sulphuric acid. Thc mixing of these two substances produces a lowering of temperature.HydrochZo& mid HC1 +n Aq.-In this case C = 1% -28.39 + 1.10 I 268 n n2 The specific heat of hydrochloric acid solutions even of the most concentrated is always less than that of the water itself which they contain. ABSTRACTS OF CHEMICAL PAPERS. Sodium Chhide NaCl + 12 Aq.-The formula is C = 18u -20.45 + 481 2100 -_. 1L 722 Addition of water to a solution of chloride of sodium always occasions a diminution of the molecular specific heat. A solution containing about 18 molecules of water has the same molecnlar heat as the water which it contains ; in more dilute solutions the molecular heat is less than that of the water contained in them. Szcgar C12,H2201, + 1% Aq.-The experiments lead to the conclusion that the molecular heat of sugar in the liquid state is 147 and its specific heat 0,430.The molecular heat of any solution of sugar will then be the sum of the molecalarhents of the water and the sugar they coiit ain . Soliitions in Sulyhiile of C~ir-bov Specific heat of snlpliide of cai*ti.b011. . . . . . .. 0.238 Molecular heat . . .,. . . . ,..... :... . 18.1 Solutions of the following substances in sdphide of carbon were examined namely sulpl~u~, phosphoi-us bromine and iodhe. The experiments show that the diminution of specific heat resulting from solution or from dilution is either not observable at all or is sliglit (sulphur and phosphorus). The molecular heat of these solutions above all never becomes inferior to that of the solvent alone.Geizeral Obse~~ations.-According to Kopp and R'egnault the molecular heat of a compound and of an alloy is always nearly equal to the SLIM of the molecular heats of its constituents. As regards aqueous solutions it appears however that while solutions of sugar and ammonia are in conformity with Kopp and Regnault's approxi- mate law the molecular heat of mixtures of alcohol and water is always above the sum of the molecular heats of its constituents. In the case of most salirie solutions 011 the other band A diminution of molecular heat tnkes place. If all solutions behaved in a similar manner this anomaly might be simply due to the difference in physical condition between the solid and the liquid state; but as various solutions behave very differently it must be due to a chemical cause.Thus we may assume that every change of temperature involves a change in the chemical constitution of the solution such chemical work being either a source of absorption or of disengagement of heat. This of necessity augments or diminishes that which must be transmitted to the solution to change its temperature and consequently the heat alters its appa-rent specific heat. Pfaund le r who has previously" expressed this same idea has more recently? even proposed the study ofthe specific * 3.pi'. Chem. vo1. ci p. 507. + Zeitschr. f. Chemie [2] vi p. 66. PHYSICAL CHEMISTRY. heats of solutions and their elements as a means of determining the degree of dissociation produced in them by heat.It appears useful to enunciate or recall these theoretic ideas at the present time even though it may be difficult to explain the opposite effects observed in mixtures of alcohol and of sulphuric acid with water by this hypothesis of a change in the chemical constitution of the solution according to temperature A. D. On the Spectra of Carbon. By W. MARSHALL D,Sc.* WATTS THISpaper is the sequel to one which appeared in the “ Philosophical Magazine,” for October 1869. The author gives the readings of the lines obtained by passing the spark from an induction coil through carbonic acid or carbonic oxide a Leyden jar being included in the circuit. These readings he converts into wave-lengths by means of an interpolation curve founded on the observation of twenty lines whose wave-lengths are given in An g str om’s map.s. w. On the Examination of the Bessemer Flame with Qoloured Glasses ad with the Spectroscope. By J. M. SILLIMAN.? PROFESSOR 81LLIMAN treats his subject under two headings-lst the examination of the Bessemer flame with coloured glasses ; and 2nd with the spectroscope. The results of the first part are confirmatory with slight variations of Rowan’s observations. The author in his experiments used three coloured glasses two light yellow and one blue through which the sunlight appeared of %I deep purplish-blue tint. In the second part after narrating the work done by Roscoe and Lielegg the writer describes his own instrument and the order observed in his work. The instrument is provided with a single equiangular prism and a reflected scale.In the course of his experi- ments he made the important observation that a mwement of the eye before the eye-glass occasioned a similar movement of the lines of the spectrum along the scale on which their position could be made to differ more than half a degree. To obviate it however the position of the eye before every reading was adjusted SO as to bring the sodium line always on 50”. He has failed to find some of the lines given by Lielegg but has detected others not given by him. The lines of which Professor Silliman gives readings are thirty-three in number :-1st Period 23&,35 50 135. 2nd Period 23+ 35 43 44 a&, 45&,46 4’74 484 50 52 53 56 564 6lQ 62 62+ 63 65 66+ 67$ 70 72 120 135.* Phil. Mag. [4] xli 12. t. Phil. Mag. [4] xli 1. ABSTRACTS OF CHEMICAL PAPERS. 3rd period 23$ 35 43 4A 443 454 46 47& 484 50 514 52 53 56 564 57 61$ 62 624 63 65 66* 67 67+ 70 72 100 102 103 105 108 135. Amongst the dark bands the most intense were- &-46 51-55 56-58 62-64& others at 33-344 36&,37& 38&,40 68 7.2. The author discusses at some length the theory adopted by Wed-ding that the aboence of the spectrum at the beginning and end of the blow is due to the small quantities of the bodies volatilized and inclines to consider that in the ease of the manganese spectrum the lack of sufficient flame may accouut for its sudden disappearance at the termi- nation of a blow. In conclusion the author suggests the use of more delicate instruments and augurs much good to the science of spectrum analysis by careful observations of the Bessemer flame.S. W. 018 the Exarnimtion of the BCessemey Flame Iruitli Colowred Glasses aid PARKEX.* un'th the SpectroscoTe. By J. SPEAR THEcombination of coloured glasses used by Mr. Parker in his in-vestigation consisted of one light cobalt-blue and one amber coloured. He does not approve of a deep blue glass as the flame under such cir- cumstances merely shows varying shades of crimson. With regard to the utility of using coloured glasses the author considers that they me of advantage to the inexperienced and tend to preserve the eyes but that the skilled workman is able to detect the change with surprising accuracy with the naked eye.In his spectroscopic examination Mi*. Parker made use of a direct vision instrument of five prisms. The spectrum obtained by him does not vary from that obtained by other investigators. The presence of an absorption-band is considered by him as merely owing to the effect of contrast. He thinks that the first group of green lines and the prominent red group cannot be referred to manganese. He has obsemed the most promiqent bright lines especially the two green groups when the metal is poured out of the converter into the ingot- mould a large flame appearing simultaneously. The writer thinks the spectrum in this case " is caused by the graphite with which the moulds are lined to fill up any cracks or cremces. and thus facilitate their ready separation from the ingots and must therefore be due to the combus- tion of carbon by the air carried down with the stream of metal at an intense white heat."? 8.w. * Chem. News xxiii 25. .t. Observations on the two preceding papers hsve been published by Dr. W.M. Watts (Chem. News xxiii 49). PHYSICAL CHEMISTRY. On the Electmnotive Fowe on Contact of Di'eyent Metals. By E. EDLUND.* INzt previous paper the author has shown that if a voltaic current tra- verses an electromotor in the same direction as the current produced by the electromotor itself an amount of heat is absorbed in the electromotor which is proportional to the electromotive force multiplied by the intensity of the current. If the current is in the opposite direction a quantity of heat is produced which is proportional to the same product.For the same intensity of current the quantikies of heat absorbed or produced in various electromotors are therefore proportional to the electromotive forces. If then a current is traversing a conducting wire consisting of two different metals there must be an alteration of temperature at the place of junction because there exists at that place an electromotive force. Now experiment has shown that heating or cooling occurs at the place of contact between two metals when a voltaic current traverses it and that this alteration of heat is as theory requires proportional to the intensity of the current. Hence the measurement of the quantities of heat absorbed or produced by the voltaic current gives a determination of the magnitude of the electro- motive forces produced by the contact of the metals.Now the quantities of heat produced by the passage of the current are of two sorts. Firstly heat is produced owing to the voltaic resist- ance of the wire in quantity proportional to the square of the intensity of the current ; while secondly an amount of heat proportional to the intensity of the current is either absorbed or produced at the point of contact of the two wires. Now let s be the intensity of the current and vz and R two constants then s2m will be the heating effect due to the voltaic resistance and A s77 the heating or cooling due to the action at the point of contact of the two metals.Further suppose the index to have moved A + a divisions with the current passing in one direction and A + a' division with the current passing in the opposite directions. We shall have Sam & sn = A + a s2m SIL = A + a' and 2s12 = ci -a'. The difference between the two stationary positions of the &leg when the current passes in opposite directions is thus a measure of the heat produced or absorbed at the point of contact of the two metals. Experiments made on this principle gave the following electromotive series Bismuth argentan (German silver) platinum copper and iron -silver and zinc being undecided. The relative numerical values are :-* Phil. Mag. [4] xli 18. ABSTRACTS OF CHEMICAL PAPERS. 100 Bismuth-copper ................141.3 Argentan-copper ................ 15.57 Platinum-copper ................ 7.37 Copper-iron .................... 17.83 Experiments were next undertaken in order to ascertain the thermo- electric relations of these combinations. The results when calculated for a difference of temperature of 10" and a conductivity =100 yielded the following deflections of the magnetometer :-Bismuth-copper the deflection ........ 92.27 Argent an-copper ........ 23.18 l? Platinum-copper ,> ........ 8.23 Zinc-copper ........ 0.90 ?I Silver-copper 9 ........ 0.63 Copper-iron ........ 24.93 97 The thermoelectric series of these metals is therefore the following Bismuth argentan platinum zinc silver copper and iron. In the former series the position of silver and zinc could not be determined owing to the slight effect produced by their combination with copper ; the other metals are however in the same order in both series.If the numbers in both series be calculated so as to be equivalent for one of the combinations-copper-iron for example,-we obtain-Thermoelectric Electromotive series. series. Bismuth-copper.. .... 92.27 197.6 Argentan-copper .... 23.18 81.77 Platinum-copper .... 8.23 10.30 Zinc-copper ........ 0.90 - Silver-copper........ 0.63 - Copper-iron ........ 24.93 24-93 The combination bismuth-copper was once more examined in regard to its thermoelectric and electromotive forces ; the results agreeing substantially with the above. It will thus be seen that although the number for the combinations argentan-copper and platinum-copper are nearly equal in both series yet as shown by the combination bismuth- copper the electromotive and thermoelectric forces are not proportional to one another.According to Seebeck thesemetals have the following order in the electric tension series :-silver platinum copper iron bismuth and zinc. There is thus no similarity between this series and the other two ;and hence it is highly probable that the electrical tension does not depend exclusively 011 the contact between the two metals but on the layer of gas or water which is condensed on their surfaces. On the other haQd the metals which in contact with each other produce the PHYSTCAL CHEMISTRY. greateah electromotive form also produoe the most powerful thermo- electric current when the place of contact is heated; but these thermo-electrical currents are not in all combinations proportional to the corresponding electromotive forces.A. D. On some Hydro- and Themno-electric Forces reduced to the Siemens’ Unit Resistance and weber’s unit of Current. By T. KOHLRAUSCH and M. A. AMMA”.* THEelectromotive forces me expressed accordingto Ohm’s law o =wi; where the resistance w is expressed in Siemens’sunits the intensity i in the magnetic unit of Weber. The electromotive forces thus measured qre given as Siemens-Weber. Hydro-eZectric circuits measured by tangent compass- 1. Grove’s element (sulphuric a,cid 1.06 sp. gr. zinc freshly mal-gamated) = 19.98.Siemens-Weber. 2. Daniell’s element (sulphuric acid and zinc as above) =11.71 Siemens- Weber. 3. Copper-zinc elemen4 (sulphuric acid and zinc as above) = 1082. Siemens- Weber. Thernm-electric circuits measured by Poggendorffs compensation method. The metals were hmd-drawn wires of about 1millim. diameter one junction having a temperature of about 16” C. the other one of to higher the eloctrornotive force e (in Siemens-Weber) is found. For German silver and copper- e = 0*0001549t+ 0*000000291t2. For copper and iron-e =0*0000969t+ 0~0000000149t2. F0r German silver and iron-e = 0.0002476t + 0~000000196ta. The values of e thus caclulated agree very closely with those found by direct observation. A. R. Polarization of Metallic 8zcrfaces in Aqueous Solutions a mew 2MetTLoc-j of obtaining Elwtricity from Mechanical Force afid certain relations between Electrostatic Induction and the decompositiow of Water.” By C.3’. VARLEY.~ THZauthor describes an apparatus by which he obtains electrio currents from polarized surfaces of mercury ; by a mechanical arrangement he ahm fhe rehkive amount of the polarized surfaces of the elements of # Phil. Mag. [4] xli 15’7. + Proc. Roy. SOC. xix 243. VOL. XXIV. K ABSTRACTS OF CHEMICAL PAPERS. the battery and by such change obtains electrical currents. Thesecond part of the paper refers to the electrostatic capacity of platinum plates in dilute acid and water. C. G. '(On a constant form of Daniell's Battery." By Sir WILLIAM THOMSON.* THEauthor employs the following form of element.:-The ce!l is of glass ; in form cylindrical or rectangular with a flat bottom. The depth may be 10 centimetres or more where perma- nence and ease of management are of more importance than very small internal resistance. A disk of thin sheet copper is placed at the bottom of the trough; to this is soldered or riveted a copper wire insulated with gutta-percha passing up vertically through the liquid ; and with this the zinc of another element can be connected. A grating of zinc to which is attached a suitable electrode is supported in the upper part of the jar. A glass tube (the charging tube) a centimetre or more in internal diameter expanded to a funnel at the top is supported so as to rest with its lower open end about one centimetre above the copper.A glass siphon with cotton-wick core or a capillary glass tube is placed so as to draw liquid gradually from a level about a centimetre and a half above the copper and to discharge the same at a level slightly higher than the upper surface of the zinc grating. The jar is then filled with semi-satnrated solution of zinc snlphate. To put the cell in action finely broken crgstals of copper sulphate are placed in the funnel at the top of the charging tube. The liquid stratum below the aperture of the tube thus becomes saturated with copper sulphate. The cell is now ready for use and may be kept so by occasionally pouring in fresh water or water onequarter saturated with zinc sulphate at the top of the cell to replace the liquid removed by the siphon from near the bottom.The author recommends the use of specific gravity bulbs kept floating in the liquid to show with precision whether the liquid added from time to time should be pure water or water more or less saturated with zinc sulphate. The best results are obtained when the liquid in contact with the zinc is a little less than half saturated with zinc sulphate. The siphon extractor mast be arranged to carry off all the water of crystallisation of the copper sulphate decomposed in the cell and enough of water besides to mrry away as much zinc sulphate as is formed in the use of the battery. C. G. * Proc. Roy. Soc. xix 253. INORCIANIU CHEMISTRY. On Solutims for Electrodeposition of Copper and Brass.By W. H. WALE”+. A SOLUTION containing one pound of cupric sulphate and one pound of sulphuric acid to the gallon of water deposits the metal in a solid compact mass with a somewhat botryoidal surface. The addition of 1 ounce of zinc sulphate (as recommended by Napier) annuls this botryo’idal form and renders the deposit tough compact and even. From a solution containing a greater proportion of zinc sulphate the metal is deposited in tufts of needles standing at right angles to the surface of the metal. Ordinary electro-brassing solutions show the same peculiarity’in even a more marked degree and this makes it im-possible to produce a good deposit of more than 0.01 to 0.03 inch in thickness. This form of deposit is owing chiefly to a copious evolution of hydrogen taking place during its formation.However the author has found that by employing a solution containing both the oxides an2 the cyanides of the constituent metals together with some neutral ammonium tartrate this evolution of hydrogen may usually be avoided or should it nevertheless take place to a slight extent it may be entirely stopped by the addition of some cupric ammonide. Such a solution yields brass of a uniform character and the deposit which may be obtained of any thickness desired is tough and has a compact even texture. aS there is no evolution of hydrogen no electric force is wasted and perfect results may be obtained with a single Wollas- ton’s or Smee’s cell. A D.