摘要:

160 HUNTER ON THE ABSORPTION OF XI.-On the A bsopption of IGpours by Charcoal. By JOHN HUNTER M.A. F.C.S. Chemical Assistant Queen’s College Belfast. TKE paper which I had the honour of laying before the Chemical Society early’last session contained the results of a series of experimentg on the absorption of vapours by cocoa-nut char- coal. Since that time I have determined a large number of absorptions which are given in the present paper. In con- sequence of the difficulty of using a liquid having a much higher boiling point than oil of turpentine in the apparatus pre- viously described it was necessary to adopt an altogether different method which would enable me to observe the absorp- tion of vapours heated in a bath of paraffin. For this purpose a copper vessel A was employed into which the absorption tube B was introduced by means of a tightly-fitting cork.The neck into which the cork was fixed consisted of a cone-shaped double chamber which allowed the melted para5 to flow in between the two surfaces so as to protect the cork from being destroyed by the heat of the gas. The sides of the vessel ex- tended below the bottom in ordcr to prevent the flame flaring up on the outer surface. The heat was applied to the bath by VAPOURS BY CHARCOAL. means of a hollow ring supplied with gas-jets which fitted on the stand F. The lower extremity of the absorption-tube dipped into a carefully graduated glass vessel C filled with mercury. n In performing an experiment the graduated absorption-tube B was first introduced into the paraffin bath A and securely fastened by means of the cork; it was then filled with mercury and inverted in the glass vessel C.The level of the mercury in C was observed the capsule containing the liquid whose vapour-absorption was to be examined introduced into the tube B and heat applied to the copper vessel. When the desired temperature was indicated by the thermometer D sus-pended in the paraffin bath the mercurial level in C was again read and the charcoal introduced as in the former experiments. AS the absorption proceeded the mercury was depressed in C and when this remained constant the level was again observed. The value of the divisions of the absorption-tube B being known the difference in height of the mercury in the tube and bath could be determined and the absorption deduced by a simple calculation.In the following tables containing the vspour-absorptions at varioura temperature@ it will be noticed that from 1%ioC. to HUNTER ON THE ABSORPTION OF 200"C. one volume of cocoa-nut charcoal absorbs 110.7volumes of vapour of aniline 102-0of carbolic acid and 101-1of hydride of beneoyl. I have examined thi3 absorption of several vapours by meam of the apparatus described in a former paper and found that aldehyde acetic ether and acetone are absorbed respectively 138-7 116.0 and 104.6 at looQC. by one volume of cocoa-nut charcoal In the tables v represents the number of volumes of the vapour absorbed by one volume of cocoa-nut charcoal at the temperature and pressure at which the experiment is performed.T and Fare the initial and final temperatures; p and p the pressures deduced by subtracting the difference in level from the height of the barometer. ANILINE. V T T P P 113.6 ,.,. 1906.6 20?*8 .... 6043 587.0 1089 .... 200'0 20Z05 .... 602.3 600.8 1105 .... 194.0 193.0 .... 603.2 588.2 Mean..... 1.10:7 .... 196.8 199'1 .... 603'3 692.0 CARBOLIC ACID. 106.2 .... 195.3 197-5 ,... 596.8 592.3 100.0 .... 195'0 191.0 .... 604.3 585.4 100.0 .... 103.5 193-5 .... 590.1 5'17'4 Mean.. ,. 102.0 .... 195'3 194.0 .... 597.1 585.0 HYDRIDE OF BENZOYL. 101.8 .... 195.7 198'0 .... 551.8 542.9 100.0 .... 192.5 191.0 .... 577.8 568.5 101.6 .... 202.0 2005 ....582.8 573.3 Mean.. .. 101.1 .... 296.7 196.6. .. .. 670.8 561.5 BXJTYRIC ACID. 83'0 .... 195'3 19$5 .... 591.1 676.4 83.3 .... 197.0 199.2 .... 592.8 677.6 88.8 .,.. 199-2 199.3 .... 675.1 556.9 82.1 .... 197.7 197.0 .. .. 585'6 5'70.1 Mean.. .. 84.3 .... 197.3 197.5 ..,. 588.1 570.0 BUTYRIC ETHER. 72.0 .... 201-0 199.q .... 596.3 591.4 75.0 .... 198.7 197.0 . . .. 605.9 600'0 7'1.7 .... 192.0 191.5 .... 599-6 590.8 Mean ... '14.9 .... 197.2 195.8 ..,. 600.6 594-1 VAPOURS BY CHARCOAL. 163 OIL OF TURPENTINE. V T T P P 50.1 .... 19t-7 19h .... 584.0 576'3 45.5 .... 195.4 195-0 .... 597.5 593.8 48.4 .... 192.7 192.7 .... 582.5 673.6 Mean .... 48.0 .... 195'3 193.0 .... 588.3 581.2 VALERIANIC ACID .40.9 .... 198.0 198.0 .... 575.5 569.5 41.3 .... 198.0 197.0 .... 591.3 581.1 41.4 .... 197.5 107.0 .... 577.8 573.1 Mean .... 41.2 .... 197.8 197'3 .... 581.5 574.5 ALDEHYDE. 61.6 .... 155.0 157.2 .... 698.0 695.0 6'7 7 ..I. 153.5 155.5 .... 673.0 675.1 67.9 .... 159.7 156.5 .... 689.3 699.8 69'4 .... 154.0 151.0 .... 679.3 677-8 Mean .... 66.6 .... 1543 155.0 .... 683.9 686-8 136.9 .... 1.00.0 100.0 .... 688.0 673.5 137.5 .... 100.0 100.0 .... 689.5 682.5 141.7 .... 100.0 100.0 .... 684.0 686.5 Mean.... 138.7 .... 100'0 100.0 .... 687'1 680.8 ACETIC ETHER. 72.7 * .. 154.0 155.0 .... 697.6 688.5 72.4 .... 155.5 154.5 .... 691-0 672.5 69.4 .... 153-0 151.2 .... 686.5 675.0 Mean .... 71.5 .... 154.1 153.6 ....691-7 678.7 118.0 .... 100.0 100-0 .... 695.2 6779 112.8 .... 100'0 100.0 .... 675.5 663.2 114.5 .... 100.0 100~0 .... 660.5 662.5 119.0 .... 100-0 100.0 .... 674.3 658.0 Mep.... 116.0 .... a 00.0 100.0 .... 676-4 665'2 ACETONE. 63.5 .... 156.5 156.0 .... 694.7 674.7 59-9 .... 155.5 157'0 .... 688'8 6 74.3 73.7 .... 157.0 158.0 .... 692.0 666.5 75.2 .... 155.0 156.3 .... 688.8 669.3 Mean .... 68.0 156.0 156.8 .... 691-1 671.4 100.8 .... 100.0 100-0 .... 665-5 649-4 102-6 .... 100.0 100'0 .... 655.7 648.7 108.0 .... 100*0 100.0 .... 644-6 643-5 101'3 .... 100.0 100'0 .... 650-5 627.0 105-0 .... 100 0 100.0 .... 644.8 631'3 109'0 .... 100.0 100.0 .... 661.7 650-2 105.3 .... 100'0 100'0 .... 660.0 644.8 Mean .... 104.5 ....100'0 102.0 ..a. 654-6 G4V9 M'LEOD ON A NEW FOR31 OF ASPIRATOR. NITROES ETHER. V T T P P 60.1 .... 10"O.O lo"O*O .... 666.2 661-2 64.7 .... 100*0 100*0 .... 661.2 671.7 68.7 .... 100.0 100*0 .... 655.0 655'0 82.4 .... 100-0 100.0 .... 656.5 656'5 62.2 .... 100'0 10WO .... 6655 658.5 Mean .. 63.5 .... 100.0 100.0 .... 660.8 660.6 HYDROCHLORIC ETHER. 63.0 .... loo-o 100.0 .... 673.1 678.6 56.8 .... 100.0 100*0 .... 668'6 655.6 60-5 .... 100.0 100-0 .... 6'74.3 671.8 56.9 .... 100.0 100.0 .... 671.5 662.5 64.7 .... 100.0 100.0 .... 675.3 673.8 Mean .. 60-4 .... 100-0 100'0 .... 672.5 668.4 FORMIC ACID. 30.4 .... 155.0 160.0 .... 7om 697.8 31.5 .... 155-3 157.5 .... 695-0 688.5 30.7 ....156.0 157.5 .... 687.5 681.0 Mean.... 30.7 .... 156.4 158-3 .... 696.7 6wi AMYLENE. 16.6 .... 155.0 156.0 .... 662-5 656.0 22-6 .... 155.0 154.7 .... 640.3 643.3 16.2 .... 156.0 156'0 ..... 655.0 658*0 Mean.... 18.4 .... 155.3 155.5 .... ~2.6 652.4 PERCHLORIDE OF CARBON. 8.2 .... 154:O 1540 .... '706.0 702.5 4.1 .... 3 545 1.i4-5 .... 692.2 685.7 3-8 .... 155.0 155'0 .... 696.8 695'3 Mean. .. 3.7 .... 154.5 154-5 .... 6~3 694.5 8'2 .... 100*0 100'0 .... (i81*2 687.7 7.8 .... 100.0 100 0 .... 678.7 679.2 7.9 .... 100*0 100.0 .... 687.5 690.5 Mean.... 7-9 .... 1OO:O 100*0 .... 682.4 635'8

ISSN:0368-1769    

DOI:10.1039/JS8672000160

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

M‘LEOD ON A NEW FOR31 OF ASPIRATOR. XJL-On a ib2zu PorrtL oj Aspirator. By HERBERT MCL~0~. THEapparatus consists of two principal parts A the aspirator proper and B the reservoir from which the aspirator is re-plenished with water ‘The Woulfe’s bottle B is connected ky M'LEQD ON A NEW FORM OF ASPIRATOR. the tube c to the water supply the pressure on which should be as constant as possible; to the other necks of tllis bottle art fitted a small tube d open at both ends and just passing through the cork and a rather wide syphon e E1 the shorter limb of wliic5 reaches nearly to the bottom of the bottle the longer limb being placed in n wide tube f,extending downwards to a dietarice that will presently be indicated returning upwards and terminating in one of the uecks of the Woulfe's bottle A.The middle neck of bottle A is fitted with a cork carrying two tubes one g reaching to the bottom of the bottle and the other It passing just through the cork and being bent twice art right angles at about two decimeters above tlie neck of the bottle and dipping into a small quantity of water in a test tube. The third neck of bottle A is pro-vided with a syphon i having a long limb from wliich the water is discharged. The length of the long limb of this syphon must be determined by the amount of suction required. The distance between the bend of the tube,f and the neck of the bottle A the length of g above the cork and the distance between the bend of h aid the surface of the water ill the test tribe should all be about two decimeters greater than the length of the long limb of tlie syphon i.To use the apparatus water is admitted into the bottle B through c ;as soon as the bottle is filled the syphon e is started wliich empties the bottle ; the water flowing through .f' into A the air which this vessel contained being expelle 3 through h and passing t>hrough the water-valve in the test-tube. When h is filled the syphoii i is set in action and the water contained in A is replaced by air aspirated tlirough y. In the mean time the reservoir B i8 being filled. It will be seen from this description that the aspiration is intermittent. The time of inaction may be climinished by regu-"OL. sx. N 1 mi CHAPMAN ON SOME REACTIONS lating the flow horn the syphon i (by a Compression cock) in such a manner that A is emptied just before B is filled.But the aspiration may be made perfectly constant by connecting the tube g with a bell-jar standing in water and regulating the aspiration by a stop-cock placed between the bell jar and the rtppwatus through which the air is being drawn in t.his case the water will be rkise-d in the bell-jar during the exit of water from A and will sink and $0continue the aspiration whilst the bottle A is being refilled. The quantity of gas aspirated in any length cf time may be readily determined by first ascertaining the amount aspirated during each exhaustion and then by observing the time between each overflow of the syphon e.This interval \dl be found very constant and the number of exhaustiona which have taken place between any two given times may readily be calculated and from these data the amount of air aspirated. The apparatus may be employed either for slow or for rapid aspirations. Tlie one already constructed aspirates half a litre tit each exhalistion; with a narrow ayphon at e it may be worked as slowly as once in 30 minntes and with a pide syphon as quickly as once in 30 seconds. With a larger apparatus a more rapid aspiration could no doubt be obtained. This aspirator has the disadvantage of employing a larger volume of water than it aspirates of air and its arrangement is rather complcx; hit on the other hand it is composed of' m;~t,eriillswhich every chemist hag at hand and it furilishes weans of measuring the qnnntities of gas wpiritted.

ISSN:0368-1769    

DOI:10.1039/JS8672000164

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

1 mi CHAPMAN ON SOME REACTIONS By ERNESTTHEOPITRON CHAPMAN. IN a paper yublislied in the Journal of this Society August 1866 “ On some Decornpositions of Nitrite of Amy],” I stated t,lrat tlie nitrite is rtt\compusccl by hydriodic acid iodide of nrnyl and iiitric oxide Ixhg fi,i.iiicd ;hit 1have since determined txact’ly tlie nrr~ouiitof ~iit~ric: oxide litwratrtl in tliis rc.nc*tion and fiud that it falls far short of that required on the assump- OF HTIIRXODIC AICID. tion that all the nitrogen is liberated in this form. (;5HllN02 contains 11.966 per cent. of nitrogen aiid should tlierefoie yield 25.64 per cent. of NO. I have as will be seen below only been able to obtain about 18 per cent. These qiiaiitittb-tive experiments were performed in the apparatus figured below.b is a stop-cock bulbtube connected with an app;watris genera tirig hydrogen. Its tube piisscis through the cork an; 1 iucnrly t,o the bott,orn of the flask c which contains stroll4 liydriodic acid. cl d is a witlc tirbt sealed at the bottoiii iind having a small liole at e. tl is in coruiection with a potidi apparatus containing caustic potash. This is coimectecl with i~ chloride-of-calcium tube and this again with another potah -apparatus containing protochloride of iron. Finally td iis second potash-apparatus is in connection with a small tube containing caustic potash in small lumps. To use the apparatus it is first completely filled with hydrogen and the strong hydriodic acid in c gently warmetl. The stop-cock is then turned 06the tube a is removed from the bulb and the hlb filled with carbonic acid.A weighed quantity of the nitrite is then introduced into the bulb and tlie hydrogen-tihe at once replaced. The apparatus now contains no air so that the nitric oxide cannot be oxidized after it is once formed. The 8top-cock is then turned on and the nitrite of amyl allowed to run iiito the tube. It does not immediately ruu into the Iiydriodic acid but if the stop-cock be iinmediately closed remains suspended in the tube. It is allowed to pass very slowly into the hydiiodic acid by cautiously opening the stop-cock. Nitric oxide is at oqce evolved and escapes through the small aperture e which is now exactly on a level with the surface of the hydriodic acid the hydrogen with which tlie apparatus was filled having forced the hydriodic acid ,which wu originally above the aperture into the wide CHAPMAN ON SOME REACTIONS tulne d.The gas escapes in a series of very small bubbles and is of course thoroughly washed by its ascent through the column of liquid in the tube. It passes through the potash and finally into the solution of protochloride of iron where any nitric oxide is of course immediately absorbed. When all the nitrite has been forced into the hydriodic acid the bulb b is heated and hydro- gen gas again transmitted through the liquid. In this way the last traces of nitrite are forced to pass into the hydriodic acid. The hydriodic acid itself is then heated almost to boiling and the first set of potash-bulbs are surrounded by hot water the stream of hydrogen being still continued for a few minutes.The chloride-of-iron bulbs with their accompanying potash tube are then detached and weighed. As they have been weighed previously the difference in weight shows at once the amount of nitric oxide absorbed. In one experiment (A) $036 of nitrite gave -1476 of NO. Therefore 18-37 per cent. of NO. The hydriodic acid remain- ing in the flask was treated with excess of caustic potash and distilled into a standard solut'ion of sulphuric acid as it was probable that ammonia had been formed. This was found to be the case and from the amoiint of sulphuric acid neutralized it appeared that 0.0326 of NH had been produced.If we calculate from these data. the total amount of nitrogen present we obtain the following results :-From the nitric oxide .... O.OCi888 From the aminonia ...... 0.02684 Total nitrogen found .... 0.09572 Therefore the total percentage of nitrogen found is 11.91. In a second experiment (R) conducted in precisely the same manner -9646 of nitrite furnished -1708 of NO and -0415 of NH,. We had therefore 17.706 per cent. of NO. Calculating from theae results we find,- From the nitric oxide .... 0.07971 From the ammonia ...... 0-03418 0.11389 Therefore the total percentage of nitrogen found was 11.81. The theoretical percentage of nitrite is 11.966. OF HYDRIODIC ACID. That this method of estimating nitric oxide is trustworthy I have proved by actually liberating a known quantity of nitric oxide fiom its solution in perchloride of iron and estimating it in the manner described in the foregoing section.Though somewhat foreign to the subject the details of the following experiment prove beyond all question the soundness of this statement. I mentioned in the paper already quoted that nitrite of amyl is decomposed by sulphuric acid valerianate of amyl water nitric oxide 2nd sulphurous acid being produced. Thus :-2C,HllN0 + H,SO = 2H,O +SO + 2N0 + C5H9(CSHll)0,. I have determined the amount of protoxide liberated under these circumstances. The apparatus employed was in every respect similar to that already described sulphuric acid being substituted for hydriodic acid.At the close of the experiment waterwas added to the contents of the flask by means of the bulbtube thereby diluting the sulphuric acid and liberating the nitric oxide which the concentrated acid would otherwise have retained. In order to prevent an undue rise of the acid in the wide tube d the flask was tilted during and after the addition of the water. In this manner -7962 of nitrite caused an in- crease of the weight of the second set of potash-bulbs of *1998. This corresponds to 25-09 per cent. of NO or 11.71 of N the theoretical numbers being respectively 25-64 and 11.966. With these data before me it appeared worth while to attempt the conversion of nitric oxide into ammonia. With this object the nitric oxide was transmitted through boiling concentrated hydriodic acid.It was slowly absorbed and iodine was liberated. To prevent this a little phosphoriis was added. The contents of the vessel were then poured off from the phosphorus and excess of potash added. The smell of ammonia was hn-mediately perceptible. It was distilled into dilute fiulphuric acid and the distillate evaporated down to a small bulk and strong alcohol zdded. This at once occasioned a precipitate of sulpha,te of ammonium It appeared to me to be of interest also to determine the action of hydriodic acid on the nitrntm of the alcoliol radicles This action is much less energetic thin the corresponding action on the nitrites. The nitrates are riot attacked in the cold by hy- &iodic acid of sufficient strength to decompose the nitrites instantly. On boiling however the nitrates are pretty easily attacked nitrate of methyl much more readily than the corres- ponding ethyl-compound. The products in both instances are nit)ric oxide ammonia arid an iodide of the corresponding alcohol radicle.

ISSN:0368-1769    

DOI:10.1039/JS8672000166

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

By J. ALFRED WANKLYN,Professor of Clieniigt8ryat.the London Institution. A CLOSEagreement I,etween the results of an elementary analy- fiis and the theoretical percentages of carbon and hydrogeii required by a compoiind is often but a poor guarantee of the p~irityof that compound. Pure acetic ether and acetic ether mixed with aa much as 10 per cent. of common alcohol would give very nearly the same results on combustion. For 10 per cent of alcohol the difference in percentage is 0.23 of carbon and 0.4 of hydrogen. There is a similar difficulty in detecting amylic alcohol in acetate of amyl by means of a combustion. Pure acetate of amyl and acetate of amyl contaminated with 10 per cent. of amylic alcohol difler in percentage by only 0.37 in the carbon and 0.28 in the hydrogen.Indeed it seems that this very case has actually occurred in practice. The boiling point of acetate of' a'myl used to be given at 133"C. In reality as I showed some time ago the true boiling-point of the pure acetate is 140°C.-a result which has been recently confirmed by other experimenters both in this country and in France. Having had occasion to prepare a number of the compound ethers in a high state of purity I have employed a titration as the test of purity and have found it to be both rapid and easy of execution and precise in its results. Berthelot has also as is well known employed a titration-method in some of his re-searches on the ethers. The method of proceeding which I have employed is very simple. I take an alcoholic solution of caustic potash and having determined the strength of it by means of standard acid digest the ether which I wid1 to titrate with a given volume of this solution of potash.When the ether has been OF THE COMPOUND ETHEnS. 171 decomposed by the potash I determine the residual potash still imused by the ether. The difference between the potash origi-nally caustic in the volume of solution and the potash found caustic after digestion with the ether is the quantity of potash neutraliaed by the ether. The strength of the standard sulphuric acid which I use is about 4 per cent. and the alcoholic solution of potash about 6 per cent. I believe however that a higher degree of accu-racy would be attainable by having the solution still stronger.The standard sulphuric acid was made by diluting pure sul- phuric acid with water and afterwards determining the strength of the dilute acid by precipitation with chloride of barium. The standard acid was also verified with pure carbonate of soda and with oxalic acid. A burette which had been carefully cali- brated was used for measuring out the standard acid. The alcoholic solution of potash wa~prepared by dissolving potash in pure alcohol of about 85 per cent. Experiments showed that neit,her a fortnight's keeping in a stoppered bottle nor a short digestion at 100' C. altered its strength. The quantity of' alcoholic solution of potash taken for a titration was measured in a small flask with a very narrow neck on which a mark had been made with a file.The temperature of the potash- solution was observed. The capacity of the measuring flask up to the file-mark was about 50 cubic centimetres. The digestion of the weighed quantity of ether with the alcoholic potash is managed in a flask with a long neck. In general the cornpound ethers decompose with great ease and rapidity ; if necessary they might be sealed up in a digestion- tube and heated in the water-bath. All the examplcs about to be given are examples in which the digestion was managed without the employment of sealed tubes. Tlie complete clisap- pearance of the smell of the compound ether is in many C~SCW a good criterion of the termination of the decoiupofiition f.)y the potash. In titrating the solutions with the standard acid a peculiar method of reading the point of neutrality was followed.When sulphuric acid is added gradually to an alkaline solu- tion the following changes in the action on litmus paper are obseivable :-At first the colour with litmus is blue. By-and-Lye the blue colour fades and then on adding another drop of dilute sulpliuric acid the colour is distinctly red. Now in read- 172 WANKLYN ON THE TITRATION OF THE COMPOUND @THF,RS. ing off the quantity of standard sulphuric acid necessary for saturation several plans may be taken. The utmost point at which litmus-paper remains distinctly blue may be read and the earliest point at which a distinct red appears may be read. The mean between these two points may then be marked down as the required point of neutrality.The utmost point at which a distinctly alkaline reaction is preserved may be marked down or the earliest point of distinct redness may be taken. Of these three methods I prefer the second for titrations involving organic acids and have employed it in the following examplea In determining the quantity of standard sulphuric acid ae-cessary to neutralize tlre volume of alcoholic potash I have read off the utmost point of distinctly alkaline reaction and in afterwards reading off the quantity of acid required to neu- tralize the residual potash I have also read off the utmost point of distinctly alkaline reaction. By this device the difficulty of the exceedingly faint acid reaction of the organic acids is eluded.Benzoate of EtliyI. I. 6,166 grm. taken ; volume of alcoholic potash neutralised 62.1 c. c. of standard acid ; residual potash after the action of the ether neutralised 10.2 c. c. of standard acid; 1 c. c. of standard acid corresponds to 0.03062 grm. of potassium. From these data 100 grm. of benzoic ether neutralise 25.77 grm. of potas-sium. 11. 4.1580 grm. of benzoic ether taken; result 100 grm. of benzoic ether neutralise 25.78 grm. of potassium. Theory requires '26.06 grm. of potassium. Butyrate of EtlLyL-I. Ether taken = 2.020 p.; result 100 grrn. neutralise 34.10 grm. potassium. 11. Ether taken = 2.009 grm.; result 100 grm. rieutralise 33-98 grm. potasgium. Theory requires 33.70 grm. potassium. TLnlerinnate of Ethy1.-I. 3.4530 grm. taken; result 100 grm. neutralise 30.15 grz. potassium. 11. 2.5181 grm. taken ; result 100.grm. neutralise 30.77 grm. potassium. Theory requires 30-08 grm. potassium. -Diethoxalate of Ethyl.-'CO(C,H,O) .-2.7580 grm. iC(C,H,)(C,H,)(HO) taken ; result 100 grm. neutralise 24.20 gym. potassium. Theory rcquires 24.44 grm. of potassium.

ISSN:0368-1769    

DOI:10.1039/JS8672000170

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

173 XV.-Quantitative Analysis by ‘‘Limited ’’ Oxidation Examples. Lactic Acid and Diethoxalic Acid. By ERNESTT.CHAPMANand MILES H. SMITH. ITwas shown on a former occasion’ that the products obtained when organic bodies are gently oxidized are the representatives o€ the radicals contained in the bodies operated upon. It was also shown that the fatty acids are unattackable by a solution containing eight per cent. of bichr0mat.e of potash and a suit-able quantity of sulphuric acid. It is possible to effect this gentle or limited oxidation in a precise manner and in point of fact to make accurate quantita- tive analyses of organic substances by employing it. The following research affords an example of quantitative analysis made by the process of gentle oxidation.Many years ago Liebig showed that lactic acid when treated with binoxide of manganese and dilute sulphuric acid yields car- bonic acid and aldehyde. With bichromate of potash and dilute sulphuric acid the results are the same. We have determined the amount of carbonic acid liberated by a definite quantity of lactic acid when treated with bichromate of potash and sill- phuric acid. With this object lactate of baryta was formed. A weighed quantity of it was oxidized and the carbonic acid thereby liberated was determined. Repeated determinations were made with the view of ascertaining the most accurate method of making these estimations. The apparatus finally adopted was as follows :-A flaak which had a tube joined on to its neck was connected with a Will and Varrentrapp’a nitrogen-apparatus containing concentrated sulphuric acid.This again was connected with a Liebig’s bulbapparatus charged with potash and tlxis in its turn with a small tube filled with lumps of caustic potash. The neck of the flask was closed by a perforated co& through whicli passed the stem of a stop-cock bulb-tube. The nitrogen apparatus containing sul-phuric acid was surrounded with cold water. To use the * Chapman and Thorp Chem. SOC.J. Dec. 1866 [2J iv 477 “On the relation between the products of gradual oxidation and the molecular constitution of the bodies oxidized.” VOL. xx. 0 174 CHAPMAN AND SMITH'S QUANTITATIVE ANALYSIS apparatus the potash-bulbs and their accompanying potash tube are first carefully weighed and then connected with the apparatus.A known weight of the lactate or other substance is introduced into the flask which is then closed with the cork and stop-cock bulb-tube. About 150 C.C.of 10 per cent. bi- chromate solution* are then poured into the apparatus through the bulbtube the stop-cock turned off and the contents of the flask heated in the water-bath. A gentle continuous evolution of carbonic acid takes place; this of course bubbles through the sulphuric acid and is absorbed by the potash. In the course of twenty minutes or so the potash begins to be sucked back into the large bulb of the potash-apparatus exactly as in a combus- tion. When no more bubbles pass through the sulphuric acid the water-bath is removed and as Soon as air begins to be drawn through the potash-apparatus the stop-cock of the funnel tube is opened and air drawn through the apparatus by nzeans of an india-rubber tube attached to the potash bulbs.The bulbs are then detached and re-weighed. The difference in weight of course gives the amount of carbonic acid which the substance has evolved. Slight deviations from the method here described have generally entailed great falling off in accuracy. Thus :-if the sulphuric acid be not surrounded by cold water the 160-lence of its action on the aldehyde &c. is BO great that a little sulphurous acid is liberated. This also happens if the flask be boiled instead of being heated in the water-bath. The ab- sorbent' action of the sulphuric acid upon the steam causes so high a temperature in spite of the cold water that the aldehyde decomposes it and an increase in weight in the potash-bulbs is the result.It; to avoid these evils chloride of calcium be sub- atituted for sulphuric acid a portion of the aldehyde pasaas into the potash bulbs thereby occasioning an increase in their weight. But if the method we describe be adopted the results are almost a8 accurate as those of a combustion A -9042 lactate of baryta gave -2574 CO,. ?1 B 1.0242 , ,) ,2880 , Calculating from these data we find that the lactate has fur- nished the following percentages of carbon as carbonic acid * 100 grnmmes of bichromate and 125 of mlphuric acid introduced into a litre measure and the measure filled up with water.BY (( LIMITED ” OXIDATIOfi . Theoretical A B percentage. 7-76 7-69 7.62 Under (‘theoretical percentage ” we have placed one-third of the total carbon of the compound. The other two-thirds of the carbon are converted first into aldehyde and then into acetic acid. This is proved by digesting a known weight of lactate of baryta with a mixture of bichromate of potash and dilute sul-phu-ic acid (10 per cent. solution)” in a sealed tube for about 1%hours at 100”C On opening the tube gas escaped but no smell of aldehyde could be detected. The contents of the tube were transferred to a small flask and treated with zinc and sul-phuric acid. The object of this treatment was to reduce the chromic acid and thereby prevent its having any action during the subsequent distillation.The flask was connected with a Lie big’s condenser and its contents distilled to dryness. Water was then added to the residue in the flask and this also dis-tilled to dryness. The two distillates were mixed the condenser washed out and the washing added. The distillate was then treated with carbonate of baryta and boiled for some time in a flask. The baryta-salts so obtained were filtered from the excess of carbonate the latter well washed and the wash- ings added to the filtrate This latter was evaporated to a small bulk and then filtered from a little carbonate of baryta which had separated the filter and carbonate being both well washed and the washings added to the filtrate which could now contain nothing but soluble baryta-salts.It waa evapo-rated to dryness dried at 150”C. and weighed. Treated in this way 1.0166 grammes of lactate of baryta yielded -8198 grammes of the new baryta-salt or 80.64 per cent. Theoretically it should yield 80.95 per cent. A portion of this salt was tested for formic acid but this acid was absent. In another portion the percentage of barium was determined 535‘2 of substance yielded. 4892 Ba,SO, percentage of barium 53.70. Acetate contains 53.726. NOW as the general formula of the acids of the acetic series is (CH,),O, and as this formula holds good not only for any one of these acids but also for any mixture of thein it follows that if we can determine the amount of oxygen in such a mix-* When we speak of a aolutlos of such 8 percentage we always refer to the bichromate of potash not to the chromic acid.02 176 CHAPMAN AND SMITH’S QUANTITATTTE ANALYSIS ture of acids and subtract it from the weight of the acids or acid the remainder will have the composition CH,. We cannot however directly determine the oxygen; but all the acids of this series contain one eq. of replaceable hydrogen. Now this can be determined with the greatest ease. It is only necessary to convert the acids into salts and then determine the amount of base. The baryta-salt is one of the best to employ for this purpose because in this case the base can be determined very rapidly and the salts themselves can be obtained easily in a state of perfect dryness and neutrality.Taking the above example we find that 100 parts of lactate of baryta yield 80.64 of baryta-salt of the acids of the acetic series. These 80.64 parts contain 53.70 per cent. of barium or 80*64 ’53*70 = 43.304 parts of barium If 43.304 represent 100 one eq. barium .632 will represent one eq. hydrogen and 20.23 two eq. oxygen. Subtracting the barium and oxygen from the total baryta-salts and adding the hydrogen we obtain the amount of CH,. 80.64-(43.304 + 20.23) + -632 = 17.738. Now CH contains $ths of its weight of carbon which is there- fore 17*738 CH2 ’ = 15.21. This numberrepresents theper- 7 centage of carbon existing in the acetous form in the lactate. This result confirms the formula for lactic acid proposed by Frankland and Duppa.They regard this substance as oxalic acid in which one atom of oxygen has been replaced by methyl and hydrogen. Lactic or hydromethoxalic Oxalic acid. acid. Analysis of Lactate of Baryta. Found. Theory. I. 11. 111. h Carbon existing as oxatyl .... 3-76 7-69 -7.62 Carbon existing in the acetous form .............. ..... -15.21 15-24 With the concurrence of Messrs. Frankland and Duppa we have studied the action of the chromic solution on diethoxalic acid. BY "LIMITED " OXIDATION. We have effected an improvement in the preparation of the diethoxalate whereby much time is saved and a somewhat larger yield obtained. We employ freshly granulated zhc granulated as finely as possible and the mixture of iodide of ethyl and oxalate of ethyl in the same proportions as those given by Frankland and Duppa ;but in addition to this we add a small quantity of mixed-zinc-ethyl and ether.The zinc is dried on the sand-bath and introduced into a flask large enough. to contain about three times the volume of the liquid to be operated upon. The mixed ethers which have been very carefully dried are poured on the zinc while it is still so hot that the first portion boils on coming in contact with it. The mixture of zinc-ethyl and ether is then added and the flask at once placed in the cold water-bath and connected with an inverted Liebig's condenser. The water-bath containing but little water is then slowly heated till the mixed ethers begin to drop back by which time the action will have started.The water is then syphoned off In three preparations made in this way we have never found the reaction get too brisk. In about an hour and a half the reaction almost stops it is completed by heating in the water-bath. When the flask is somewhat cool though not cold as much tepid water is added as will allow of the contents of the flask being well shaken up together. The water and as much of the solid matter as can be easily removed with it are transferred to a wide-mouthed tin can. More tepid water is added to the residue inthe flask and in this way the whole contents of the flask are transferred to the tin can. The can is then heated over the naked flame. The distillate generally divides into three layers We add about 40 C.C.of ether to it and shake if up. The top and bottom layers unite and can easily be decanted from the watery part. After the oily layer has been decanted it is distilled and that portion of it which comes over below 120Ois again agitated with the watery part. It is again separated and treatedin the same manner as before. Three of four such operations are enough to obtain almost all the diethoxalic ether The fraction of higher boiling point is then dried and fractionally distilled when most of it is found to boil at 175"C There is only a very small quantity of liquid of higher boiling point not more than a drop or so. We subjoin the details of four operations :-lat. 600 grm. of mixed ethers (iodide of ethyl 409 grm. 178 CHAPMAN AND SMITH’S QUANTITATIVE ANALYSIS oxalate of ethyl 191 grm.) treated as directed by Frankland and Duppa yielded 82 grm.of the pure ether; the digestion lasted 15 hours. (The yield obtained by them and mentioned in their paper is almost the same viz. 86 grm. from the same mixture.) 2nd. Same quantities treated as tlescribed above with only three grm. of mixed zinc-ethyl and ether (containing about 30% of the former) yielded 91 grm. Digestion lasted about 5 hours. 3rd. Same quantities about 15 grm. of the mixed zinc-ethyl and ether being added yielded 109 grm. Digestion lasted 2 hours. 4th. Same quantities + 65 grm. of ether and zinc-ethyl yielded 118 grm. Digestion lasted 2a hours. Three parts of zinc-ethyl should theoretically yield about two of the ether.We will therefore subtract the amount of diethoxalate of ethyl which might have been produced by the zinc-ethyl and then the results stand thus :-1st operation 15 hours no zinc-ethyl yield 82 gr. 2nd 9 5 1P* 90 9 ,9 97 97 3rd 9 2 I 5 ? 1059,, 97 7 4th 7 2a 9 224 3 * 7 104 77 91 From this it would appear that a small quantity of zinc-ethyl greatly promotes the action but that no advantage is gained by using a large quantity. A very small trace of water impedes the action even though there is more zinc-ethyl present than would decompose it. In fact if the zinc be allowed to get cold it becomes damp enough to delay the action for an operation in all respects resembling No. 3 but in which the zinc had been allowed tostand all night in the flask the mouth of which was covered with paper lasted 9 hours.We have nothing to add to the account of the physical pro- perties of this ether given by Frankland and Duppa. It has been titrated by Professor Wanklyn and 100 parts of the ether neutralized an amount of potash-solution corresponding to 24-20 parts of potassium. Theory would require 24-44 It was therefore pure. We prepared the acid by decomposing the ether with solution of caustic potash both with and without alcohol. The pro- ducts of both operations were evaporated down to a small bulk BY "LIMITED " OXIDATION. excess of dilute sulphuric acid added and the mixture agitated with ether. The ether employed for this purpose should be free &om alcohol for the reason given below.When the ether has become charged with the acid it is decanted and dried over chloride of calcium. The ether is then for the most part distilled off in the water-bath and the thick syrupy solution thus obtained is placed over sulphuric acid and allowed to stand some days. The product is a dry white mass of crystals consisting of pure diethoxalic acid. If the ether employed contained alcohol the product would be contaminated with chloride of calcium. When diethoxalic acid is treated with bicliromate of potash and sulphuric acid and the mixture gently warmed a peculiar smell is produced and gas is evolved in abundance. This gas proved to be carbonic acid. A determination of its quantity would we thought throw light on the nature of the reaction.For this purpose we did not employ the same apparatus as that before described because with the greatest care one is apt to lose many determinations from the sucking back becoming very violent and also because with it we could only use small quantities. In the apparatus about to be described the carbonic acid is determined by loss. It will be readily understood by a refer- ence to the figure on page 180. A is a large bulb pipette one limb of which descends into the flask B and the other is bent at right angles and closed by a piece of india-rubber tube contain- ing a removable glass plug. The flask B has a tube let into the side of its neck. This tube is connected by a long india- rubber tube with a glass tube passing through the cork aud descending almost to the bottom of the long-necked flask C.Another tube just passing through the same cork is connected with the pipette D the long stem of which passes into the flask E. The cork of this flask has another aperture open to the air. E contains sulphui-ic acid. The point of D dips just so far into this acid that on sucking the air out of it it cannot be completely filled by the acid. The flask C is empty. When the apparatus is in use C is surrounded by cold water. It serves to condense steam and the uapours of any organic liquids. B contains tbe substance to be operated upon and A the bichromnte solution. The total weight of the apparatus when charged is about 420 grammes. It is weighed upon a 180 CHAPMAN AND SMITH’S QUANTITATIVE ANALYSIS balance capable of carrying a kilogramme and also capable when loaded with 500 gramrnes in each pan of indicating half a milligramme.The pipette A was charged with bichrornate solution by immersing its point in the liquid and sucking out the air. A known weight of diethoxalic acid was dissolved in water in B the apparatus put together and weighed. The bichromate aolution was then run into the flask by removing the glass plug. As sooii as it had all run in the plug was replaced C immersed in cold water and B gently warmed. Carbonic acid was at once evolved. The evolutioii lasted about ten minutes. The contents of the flask were then boiled rather sharply care being taken however not to overtask the condensing powers of C in fact the top part of it continued cool during the whole opera- tion.After a few minutes the boiling was discontinued the glass plug removed and a current of dry air forced through the apparatus. It was then cooled air being allowed to enter which had been previously -dried by passage through a chloride- of-calcium tube. The whole apparatus was then dried and transferred to the balance-case arid allowed to remain there for an hour. It was then reweighed. The loss of weight of course indicated the amount of carbonic acid. BY " LIMITED " OXIDATION. Weight of diethoxalic acid employed. . . . 3.1375 grammes. -_I Weight of apparatus before the operation 419.153 , 99 99 99 after 418.107 , Weight of carbonic acid evolved .. . . . . 1.046 99 Therefore percentage of carbon 9.093. Diethoxalic acid con-tains 6 eqs. and 54.55 per cent of carbon. By the proportion 54-55 6 9.093 x x = 1-0002 we learn how many eqs. of carbon are evolved in the form of carbonic acid. According to the theory of its composition put forward by Frankland and Duppa this substance contains 1 eq. of oxatyl and should t.herefore liberate one-sixth of its carbon as carbonic acid. 'gH5 HO = C,H,,O,. { :kJ We have therefore shown that one equivalent or 4th of the carbon has been liberated in the form of the characteristic oxidation-product of oxatyl viz. carbonic acid. This in itself is a strong corroboration of the correctness of the above hypothesis. At the end of the above operation the flask C contained in addition to water about 2 C.C.of a slightly yellow volatile mobile and fragrant liquid. A few grammes of diethoxalic acid were heated in a small distilling flask with excess of bichromate of potash and sulphuric acid. In this way more of the same liquid was obtained. It was dried over chloride of calcium and its boiling point taken. It boiled quite constantly at 101" and had the peculiar smell of Wanlrlyn's propione. The next point was to determine how much of this liquid was produced. With this object 14-3grm. of diethoxalic acid were introduced into a small retort the neck of which was dipped under the surface of solution of caustic potash contained in a small receiving flask. The object of the potash was to absorb the carbonic acid and thus prevent the loss which would have occurred had this gas escaped saturated with the vapour of organic liquid.Excess of the 10 per cent. bichromate solution was then added to the diethoxalic acid in the retort and the whole gently warmed and finally boiled. When about a tenth of the contents of the retort had distilled over the operation was stopped and the contents of the receiver saturated with carbonic acid care being taken not to pass more carbonic acid 182 CHAPMAN AND SMITH'S QUANTITATIVE ANALYSIS than was immediately absorbed. The oily layer floating on the surface was decanted and placed over chloride of calcium. The solution of carbonate of potash was partially distilled and the distillate saturated with chloride of calcium when a small quantity more of' the oily liquid rose to the surface.This was decanted and added to the main product. When it was judged that the liquid was dry it was distilled tlirongh a wry small condenser into a tared flask and weighed. The weight was 9-40 grm. We had therefore obtained 65.7 per cent. of the weight of the diethoxalic acid in the form of this liquid. As proved below the liquid is propione. We should theoretically have obtained 65.15 per cent. of it." More of the substance was prepared without any special precaution being taken to collect the total product. Even under these circumstances the yield is &om 58 to 60 per cent'. of the diethoxalic acid employed. It is i:ot however necessary to prepare diethoxalic acid.The ether need simply be decomposed with caustic potash the alcohol distilled 06 and the crude potash-salts so obtained treated directly with the oxidising mixture when the propione may at once be distilled off. Carefully dried over chloride of calcium this substance is colourless or f&intly straw-coloured. It has a peculiar but very fragrant smell. It boils quite constantly at 101. Its specific gravity (water at 4O C. = 1) is at 0" C. $145 at 15'C. 08015. It is not easily attacked by oxidising agents as is indeed sufficiently apparent from the large yield obtained. When distilled with water it all comes over with the first few drops leaving the water quite tasteless. It is soluble in about 24 parts of water much less so however in saline solutions.It appears to be quite insoluble in a saturated solution of chloride of calcium. It is of course miscible with alcohol and ether in all proportions. It was oxidised by prolonged diges- tion in a sealed tube with the 10 per cent. bichromate solution. 2.1848 grm. of the substance were digested with excess of the oxidising golution for 15 hours in the water-bath. The tube was then cooled and opened. No gas whatever escaped. The contents of the tube were transferred to a small distilling flask and treated precisely as described when speaking of the pro- ducts of oxidation of lactic acid. The distillate was converted into baryta salts and the salts dried at 150" C. and weighed. Weight 6.635 gram. The percentage of barium in these barium-salts was deter- * This slight erceas was doubtless due to moisture.BY '' LIMITED " OXIDATION. mined by conversion into sulphate. 0.5421 of the substance gave 0.4720 Ba,SO,. Therefore the percentage of barium was 51.19. The remainder of the salt was dissolved in water. It did not form a perfectly clear solution. As it was intended to fractionate the acid8 in this salt and as the baryta-salt is ex- ceedingly inconvenient for this purpose excess of sulphate of potassa was added and as much standard sulphuiic acid as would combine with about one-fourth of the barium. Of course the whole of the barium was precipitated as sulphate and the acids were obtained in the form of potash-salts and free acid.They were filtered from the sulphate of baryta and the free acid distilled off. The remainder of the salts were fractionated in the manner describedin a former paper,* with the following results:- I I Per cent. Theoretical per Salt to which Substance taken. Bassol found. Ba found. cent. Ha. this corresponds. 48.41 Propionate Intermediate Mixture-3rd , -3589 .3170 51 -94 -, *6290 '5555 51 *96 -&h ) -4201 -3845 53 .81 53 -726 Acetate From the first fraction in the foregoing table it appears that propionic acid is one of the products; from fractions 2 and 3 that no acids higher in the series than propionic acid are present; finally from fraction 4 that acetic acid is present. This fiactionation taken in conjunction with the fact that the percentage of barium from the mixed salts is very close to that required by a mixture of acetate and propionate of baryta in equivalent proportions justifies us in assuming that the mixed salts really had this composition.The theoretical percentage of bariumin the mixture C,H,BaO + C,H,BaO is 50.93. We obtained 51.19. The total amount of the mixed salts obtained was 97 per cent. of the theoretical quantity calculated on the assumptions that the above is the formula of the mixed salt and that one eq. of propione yields on oxidation one eq. of acetic and one eq. of propionic acid. However the above ex- periment had not been conducted absolutely wit,hout loss. It was therefore repeated with the greatest possible care upon a smaller quantity of propione.* Chapman and Thorp Chem. SOC. J.#Dec. 1866. 184 CHAPMAN AND SMITH’S QUANTITATIVE ANALYSIS Digested in the water-bath with the chromic solution for eight hours and treated precisely in the same manner as in the estimation of acetic acid in the lactate *4362 of propione yielded 1.3542 of mixed salts or 99.28 per cent. of the theoreti- cal quantity. A portion of these salts was carefully tested for formic acid which was absent. In another portion the per- centage of barium was determined. -4908 of the mixed salts yielded -4252 of sulphate of baryta therefore 50.94 per cent. of Ba. As above remarked the theoretical percentage for these mixed salts is 50.93. Calculating from these data in the manner previously des- cribed we fbd that 100 parts of propione have yielded 310.5 of the mixed salts As these salts contain 50.94 per cent.of Ba we have to subtract this percentage from them (that is to say 158-14) and to add to them an amount of hydrogen equivalent to this amount of barium and also to subtract twice the equiva- lent amount of oxygen; the remainder will be as already proved CH,. Amount of mixed salts .................. 310.5 Amount of H. eq. to Ba.. ................ 2.31 312.81 Ba + 0,= ............................ 232.03 Amount of CH ...................... 80.78 CH x 7 6 -C........................... 69.24 According to ow oxidation therefore propione contains 69-24 of carbon. By calculation it shdd contain 6976. We are perfectly confident that with care even a better result might have been obtained.The next thing to be determined was the amount of oxygen required to effect this oxidation. This result was approximately obtained by precipitating the sesquioxide of chromium which had been reduced fi-om chromic acid by the action of ill known weight of propione. We say approximately because the estimation is attended with some little difficulty. In the first place ammonia is inadmissible as a precipitant because it would precipitate not only the sesquioxide of chromium but also some chromate of chromium. We are therefore compelled to use BY "LIMITED " OXIDATION. potash but potash adheres so tenaciously to the sesquioxide that it is practically impossible to remove it by washing.m3435 of propione was digested for ten hours with 46 C.C. of the standard chromic solution. The tube was then cooled and opened No gas was evolved. The contents were transferred to a dish boiled and excess of caustic potash added. The precipitate produced was pure pale green. It wag washed first by decan- tation and then on the filter until the washings did not in any way affect neutral nitrate of silver did not change the colour of litmus and left no appreciable residue on evaporation. The pre-cipitate was then dried ignited and weighed. Weight *6668. On treating this with water some chromate dissolved. The whole contents of the crucible were boiled with strong hydro- chloric acid and a little alcohol. Ammonia was then added and the fluid again boiled.The precipitate was then filtered 0% washed dried ignited and weighed. Weight -6332. This pre cipitate on treatment with water again coloured it yellow thereby showing that it still contained chromate. The amount was however very small. The latter number is therefore assumed to have been very nearly the true weight of the ses- quioxide. Calculating from these data we find that 100 parts of propione had required 57.83 parts of oxygen to convert it into acetic and propionic acids. Calculating from the data given on a previous page we find that 100 of propione yielded 154.7 of the mixed propionic and acetic acids. Now these acids would contain 73.14 of oxygen. But the amount of oxygen employed was 57.83; therefore the propione must have con-tained oxygen.On subtracting one of these numbers from the other we obtain 15-31 as the amount of oxygen contained in propione. The theoretical quantity would be 18.6. This nnm- ber wide as it is of the mark proves distinctly that acrylic acid is not among the oxidation-products of propione ; for if it were we should have required a far higher percentage of oxygen than 57-83 to oxidize propione. The theoretical quantity is 55.8. The quantity required if acrylic acid were produced would be 74.4. From the nature and amount of the acids obtained it is evident that propione contains 5 eqs. of carbon. From the relation subsisting between the amount of acids and the amount of oxygen required to produce them it is evi-dent that the propione requires 3 eqs.of oxygen to convert it into acids of the acetic series. It is further evident that the 186 CHAPMAN AND SMITH'S QUANTITATIVE ANALYSIS ETC. propione can have lost no hydrogen during its oxidation. Had it done so more oxygen would have been required to oxidize it. Such being the case it is evident that the amount of hydrogen found in the form of the acids of the acetic series is the total amount contained in the compound. We therefore subjoin a comparative statement of the composition of propione as deter- mined by a careful Combustion by limited oxidation and by calculation. Combustion Limited Calculation. I. oxidation. C,. ....... 69.58 69.24 69.76 H, ...... -11.49 11-63 o... ..... -18-61 c 1oo*oo I. ,1662 grammes of propione burnt with chromate of lead gave 0424grammes CO,.The foregoing analytical results relating to diethoxalic acid are collected and exhibited in a tabular form in the following atatement Oxidation of diethoxalic to water carbonic acid and propione thus :-c(c,He) (Ho) + 0 = H20 + CO + C(C,H,),O. {CO(k$ 100 parts of diethoxalic acid gave 33.37 parts of carbonic acid. Theory 33.33. 100 parts of diethoxalic acid gave 65.7 parts of propione (weighed as propione). Theory 65-15 Oxidation of propioiiic to propione and acetic acids thus :-Propione. C(C,H,),O + 0 = C,H60 + C,H,O,. 100 parts of propione gave 310.45 parts of baryta-salts (pro-pionate and acetate). Theory 312%. The percentage of barium found in the mixed baryta-salt was 50.94.Theory 50.93. A satisfactory separation of the propionic and acetic acids was made. and it was proved that no other acid was present. From these data we give the following analysis of dieth-oxalic acid. STENHOUSE ON THE PREPARATION OF BERBERINE ETC. 187 Found. Theory. Carbon existing as oxatyl weighed in the form of CO,. .. . ..... . . . ...... . ,.... 9.10 9.09 Carbon existing in the propylic form weighed as propionate of baryta.. .... 27-29 27.27 Carbon existing in the ethylic form weighed as acetate of baryta ... . . . .. 18.20 18.18 We conclude that were any chemist called on to deduce the formula of diethoxalic acid from the data given above he could only arrive at a. formula practically identical with that proposed by Frankland and Duppa fkom synthetical evidence.Laboratory of the London Institution.

ISSN:0368-1769    

DOI:10.1039/JS8672000173

出版商:RSC    

年代:1867

数据来源: RSC

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STENHOUSE ON THE PREPARATION OF BERBERINE ETC. 187 XVL-On the Preparation of Berberine from Coscinium Fenestratum. STENHOUSE, By JOHN LL.D. F.R.S. &c. THEplant Coscinium fenestratitcm belonging to the natural order MenispemaceE is a large rope vine and is very abundant in the forests of Ceylon and other parts of India. As is well known berberine was extracted from it by Mr. J. D. Perrins many years ago," and I find that when treated by the following pro- cess it yields fiom 1Q to 34 per cent. of pure berberine accord- ing to the quality of the wood which probably depends very much on the season at which it is collected. One part of acetate of lead is dissolved in 3 parts water and to the boiling solution 1part of very finely ground litharge is added in small portions and heated until the whole forms a thick pasty mass; 20 parts of the finely ground columbo wood (coc.,fen.) is boiled with the subacetate of lead thus obtained previously diluted with 100 parts of water. After about three hours' digestion the mixture is strained through a bag-filter and the partially exhausted wood is hebted twice with the Fame quantity of water these weak liquors being used instead of wat'er in the extraction of fresh quantities of wood. The first and strongest liquor (after adding a little finely powdered litharge) is concentrated until on cooling berberine crystallises out in dark brown tufts of needles. The motl2er-liquor from * Phil. Mag. [4] iv 99. 188 STENHOUSE ON THE PREPARATION OF BERBERINE ETC.these crystals is strongly acidulated with nitric acid and allowed to stand for 24 hours when the remainder of the berberine present is precipitated as nitrate which is very insoluble in solutions containing a slight excess of nitric acid. The nitrate thus obtained may be converted into berberiiie by boiling with about 10 times its weight of water adding an excess of ammonia and allowing it to cool; but it is more advantageous to substitute hydrate of calcium for the ammonia in decomposing the nitrate as berberine does not seem to be acted upon even by long boiling with hydrate of calcium whereas ammonia potassa and sodib all decompose it more or less with formation of a dark brown substance. In order to purify the crude berberine obtained by the above process it is dissolved in boiling water and subacetate of lead added as long as any precipitate is produced.This solution filteredwhilst hot almost solidifies on cooling to a mass of yellow needles which however still contain lead and organic impurities. They are collected on a cloth filter pressed dissolved in boiling water and sulphurett'ed hydrogen passed through it. The hot rsolution after filtration to separate the precipitated sulphide of lead which carries down some organic impurities is acidulated with acetic acid and allowed to cool. The bright yellow needles of nearly pure berberine are collected pressed and dried at a gentle heat. If required quite pure they may readily be obtained so by one or two recrystallisations from boiling water.Berberine is insoluble in benzol and bisulphide of carbon. The berberine in this wood seems to be combined with an organic acid forming a salt soluble with difficulty even in boiling water. So that by treating the wood with water alone a clear yellowish brown solution is obtained which becomes turbid and opaque on cooling; if this be now precipitated by subacetate of lead and evaporated it yields but a very small amount of berberine for the quantity of water employed. By boiling the wood however with subacetate of lead almost the whole of the berberine is at once extracted. This process of boiling with subacetate of lead will no doubt be found equally applicable to the extraction of berberine -from any of the other plants in which it is found. Theine.-I have successfully applied the above process to the extraction of theine from tea.

ISSN:0368-1769    

DOI:10.1039/JS8672000187

出版商:RSC    

年代:1867

数据来源: RSC

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XVIL-On the Amount of Carbonic Acid contained in Sea-Air. By T. E. THORPE,Dalton Scholar in the Laboratory of Owens College Rlnnchester. THEexistence of carbonic acid in the air of the land was first demonstrated by &lacbride,* of Dublin so far back a8 1764 but its invariable presence in the atrnosphere of the 8ea wa8 not proved by experiment until 1836. The experiments of Saussure Boussingault AnguB Smit,h and others furnish exact knowledge concerning the distribution of the carbonic acid contained in the air of theland together with the causes and limits of its variations due to differing circumstances of situation and weather determina-tions of its amount in the air over the sea under as far as possible similar conditions are alone wanting to render the history of this particular constituent of our atmosphere toler- ably complete.In his well known memoir on the carbonic acid of the atmosphere the younger Saus suret clearly showed the influ- ence which large bodies of water exert on the proportion of this gas in the air. Thus fi-om simultaneous observations he found that air taken near the middle of the Lake of Geneva contained on the average slightly less carbonic acid than the air of the land taken at a short distance from the bank the ratio of the amounts of oarbonic acid at the two stations being as 95 to 100. This abstraction of carbonic acid by the waters of the lake night with all probability have been foreseen in fact Vogelf had previously obtained a similar result and deduced a like conclusion from a comparison of the turbidities produced in baryta-water by the air of the Channel and of Dieppe.To such an extent was this action supposed to occur that it was formerly believed the air over the open sea would be found to contain absolutely no carbonic acid ; indeed Xriiger 5 was unable to detect'its presence over the Baltic; Emmet and D a1t on,ll however thirty years ago conclusively showed that it is invariably present even in the air of' mid-ocean. * Experimental Essays 1764. .1. Ann. Ch. Phys. xliv 1830. $ Ann. Phil. N. S.,vi '15. 8 Schw. J. xxxv 379. II Phil. Mag. (41 xi 225. VOL. xx. P 190 THORPE ON THE AMOUNT OF CARBONIC ACID The only series of determinations hitherto published of the amount of carbonic acid contained in the air above the ocean are those of Lewy.* At the request of the French Academy Lewy in 1848 collected the air of the Atlantic at different times during a voyage from Havre to Saata Marta and deter- mined the proportion of its three principal constituents in the eudiometric apparatus of Regnault and Iteiset.The -following table shows the results of these determi-nations :-TABLEI. Lewy'a Analyses of tlre Air of the Atlantic Ocean. Each result the mean Of Dee. Temp remp Lat. Long u three analyses. Hour. of of Wind. Sky. w.0 8E 1847. Air. Sea. N. Paris d $2 -L- z-3 CO,. Oxygen Nitrogen --I .I eaguer 1st 11.30 a.m. lt%C 5.S.E. Cloudy 4730 16o.d 55 4.881 2105'170 7889,949 Left Havre on Nov. 25th. Weather con-tinued wet whilst in the Channel.4th 3.0 a.m. 13.0 N.W. UnclnucTed 47.00 13.0 120 3.388 2096'321 790V341 8th 12.15 p.m. 17'5 N.E. Few c:ouds 35'40 20'35 190 5.495 2105'915 7885'558 54 leagues from Ma-deira. 17th 3.0 p.m. 23.0 do. Unclouded 22-5 39-0 400 Vi71 21C6.030 7858'199 30 leagues south of the trOlJicS. 18th 3.0 a.m. 21*5 E. do. 21.45 41-3 435 3,346 2096.139 7900'515 Midway bet ween Africaand America. Sea very phospho- resent. 18th 3.0 p.m. 240 ao. Few clo1xls 21.9 4P25 412 5.4201 2106'099 7888' 181 19th 3.0 a.m. 2" 0 do. Unclouded 2035 43-35 390 3'388 2096'074 7900'538 Sea very phospho-resctnt,. 26th 1.0 p.m. 27 2 ao. do. 15-49 64-28 80 3288 2105'889 7888.823 18 Ieapues from Mar-tiI ique 28th 2.15 p.m. 27.0 do. do. 146 i0.4 60 5.0931 '2105,686 7889'221 45 leagues from Curaqoa.30th 12.30 p.m. 25 5 N.E. do. 125 56.0 15 5'143 2105'789 7889'068 15 leagues from Santa Marta. 31at 3.0 a.m. 24 0 E. do. I -I tci 2 3'767 2101-114 7855'119 Entering the port of Santa Harts. The mean composition of the air of the Atlantic from these analyses is therefore in 10,000volumes :-Carbonic acid ........ 4-630 Oxygen.. ............ 2102.750 Nitrogen ............ 7892.620 10000~000 These numbers differ but slightly from those usiially given as representing the average composition of the atmosphere of * Ann Ch. Phys. [3j xxxiv 5. COKTMNED IN SEA-AIR. the land. On examining the experimental details however it appears that the air of the day was found to be considerably richer in carbonic acid and oxygen than the air of the night.The following are the means of each series :-The day. The night. (7 exieriments.) (4 experiments). Carbonic acid ...... 5.299 3.459 Oxygen .......... 2105.801 2047.412 This remarkable difference appeared to become greater as the middle of the ocean was approached where the air of the sea was less liable to be mixed with that of the land. The means of the analyses of air collected by Lewy at about equal distances fiwm the continents at the same hours night and morning of the same day and under similar meteorological conditions are as follows :- At 3 a.m. At 3 p.m. Carbonic acid ...... 3.346 5.420 Oxygen .......... 2096.139 2106.099 or a difference in 10,000 volumes of air of 2.074 in the carbonic acid and 9.960 in the oxygen.These singular diurnal variations in the composition of the atmosphere of the sea are ascribed by L e wy to the evolution and consequeiit admixture with the superincumbent air during the daytime of dissolved gases from the heated surface-layers of the sea such gases being considerably richer as is well Icnown in oxygen and carbonic acid than ordinary air. During the night on the other hand this disengagement of gas ip supposed to be arrested. Morr en," aiid subsequently Lewy,? have shown that the changes in the relative amounts of the several gases held in solution in sea-water depend :-(1) upon the variations in intensity of direct and diffused solar light produciiig a corresponding effect upon the vitality of sea-plants and aiiinials ; and (2) upon the alteratioiis of tempera-ture affecthig the relative amounts of these dissolved gases in accordance with the known laws of gaseous absorption.Con-frequently if ~nchcaiises can at all influence the composition of the atmosphere of the sea it is reasonable to expect that the variations would be most perceptible in the air above the * A4nn.Ch. Phgs. [3] xii 5. .I.Ann. Ch.Phys. [3] xvii 5. P2 192 THORPE ON THE AMOUNT OF CARBONIC ACID tropical oceans in whose tepid waters infusoiia exist in enormous quantities arid where the intensity of total sunlight is very great and its changes exceedingly rapid. It would thus appear from Lewy's experiments that the mean quantity of carbonic acid in the air above the ocean is sensibly greater than in the air of the land and that contrary to the statements of Vogel and Kruger sea-water does not abstract the carbonic acid from the air but even causes a sensible increase in its comparative amount.Considering the difficulty generally experienced in accurately measuring in the eudiometer contractions so minute as the absorption of the carbonic acid from a small volume of atmospheric air it appeared desirable to test the validity of the above coiiclusions by a series of experiments made by one of the more convenient and accurate methods which we now possess for the estimation of atmospheric carbonic acid. In a paper read before the Literary and Philosophical Society of Rlanchester," I communicated the results of a serie8 of determinations of the amount of carbonic acid contained in the air over the Irish Sea.The followiug contains in addition to these the results of a more extended inquiry on the air over the Atlantic Ocean. All these determinations were made by P et t enk o fer 's method,? according to which the amount of atmospheric carboiiic acid can be estimated with far greater accuracy than by any eudioinetric method hitherto described. It consists in absorbing the carbonic acid from a known volume of air by means of baryta-water free fi-om allzalies and of known strength the amount of carbonic acid so absorbed being ascertained by tho difference in the amounts of st.andard acid required for the exact neutralisat'ion of the baryta-water before and after the absorption.Any weak acid which is not volatile at ordinary temperatures may be employed for this purpose ; but oxalic acid is preferable for obvious reasons the only objection to its use being that its solution requires to be often prepared anew since it is apt to decompose when kept for any great length of time. The solution of oxalic acid used for these experiments was made so that one cubic centimetre corresponded to one milligramme of carbonic acid it thus contained 2.864 grammes of pure crystallised oxalic acid per litre. Twenty-five cubic centimetres of the baryta-solution * Mem. Lit. Phil. SOC.[3] vol. iv. t Chem. SOC.Qu. J. x 292. CONTAINED IN SEA-AIR. were originally made to correspond to about twenty-eight or thirty of oxalic acid but of course the exact strength was known previous to each experiment.The bottles were gener-ally filled with the air by means of the bellows-pump but sometimes when the wind was strong it sufficed to hold them up for a minute or two 111 such a manner that the air could circulate freely within. After the admission of the baryta- water the bottles were closed by metallic caps provided with a caoutchouc flange fitting air-tight to the necks. The baryta- water remained in contact with the enclosed air for about an hour during which time the bottles were fkeqireiitly agitated. Although even this is longer than esperience has shown to be actually required for the complete absorption of the carbonic acid still in several of the experiments the bottles were allowed to staud for thee four or even six hours before the solutions were titrated.Fifty cubic centimetres of baryta-water were employed in every case to absorb the carbonic acid of which twenty-tive were afterwards withdrawn to determine the amount go neutralised. A Mohr's burette was used for which a table of capacity had been previmsly constructed by weigh- ing and interpolating in the ordinary way. From the data thus obtained the volume of carbonic acid in 10,000 volumes of air is easily calculated by means of the following forniula in which p represents the dift'erence between the amounts of oxalic acid required for exact neutralisation before and after the absorption or since one cubic centimetre of the oxalic acid solution corresponds to one milligramme of the carbonic acid the amount in milligramnies of the car-bonic acid contained in the quantity of air experimented upon P the capacity of the flask ; v the volume of baryta- solution employed for absorption ; H the observed height of the barometer ; and t the observed temperature :-p (1 + 0003667 x t)760 H( V-w)O.O01W14 The calculation of a large number of determinations is much facilitated by the use of a table showing the weights in grammes of a cubic centimetre of carbonic acid at different temperatures and pressures and by employing a constant volume of baryta-solution in the experiment.If v' be the reduced volume of air and w the weight in grammes of a cubic 194 THORPE ON THE AMOUNT OF CARBONIC ACID centirnetre of carbonic acid at the observed temperature and pressure the formula becomes P v/ x w.The experiments on the air of the Irish Sea were by the kind permission of the Honourable Board of Trinity House made during the month of August 18G5 on board the "Bahama Bank " light-vessel situated in lat. 54"21' N. and long. 4' 11' W. seven miles W.N.W. of Ramsey Isle of Alan and conse- quently nearly equidistant from the shores of England Scot- land and Ireland. This ship is placed to mark the proximity of a dangerous bank by which for the greater part of the day a strong current setting iii from the southward flows through the North Channel and into the Atlantic. The times of obser-vation were 4a.m.and 4 p.m. the hours of nearly minimum and maximum temperature when it was assumed that any differences in the air of night and day similar to those observed by Lewy over the Atlantic would be most perceptible. The capacities of the two bottles A and B which served for all the determinadons were respectively 4815 cb. c. and 4960 cb. c. The following table containing all the experiments which were made gives the results of these determinations :-TABLE11. Shozoing t?k Amount in Volumesof the Carbonic Acid in 10,000 Volumesof t?he Air over tlte IrLh Sea determined by Pe ftenkofw'e Metkod. I Carbonic acid. c Date. . No. Bar. 64 1865. gc% Dry. Wet ---B -1 August 4th 762'5 16.4 11'1 16-0 Day very flne and clear.7 5th 762.0 13'9 12'9 15'0 S.W. by S. Light breeze 2.93 3.05 3 , 5th 761.2 16-1 14'4 15.0 S.W by S. 3.08 3.21 ,$ 7th 753'4 14.2 13'3 15'0 S.W. by S. L&ht 3'30 3.22 Baryta -water ex-posed 3 hours. 5 ,*, 7th 157'5 17-2 15'1 15.6 N.W. 3.20 3-15 Sunny. Very Ane. 6 8th I 60.2 13'6 12'2 15'0 N.N.W. Mode)& 3'06 3'19 9 8th i61.0 18'3 13'1 16.0 N.N.W. Lightbreeze 3'32 3.02 Fine and sunny. 1 I 1 9th 758.7 13'3 12'2 15.0 S.W. by W. ,. 2'93 3.10 9 9th 756'4 1z.o -15.0 S. by W. Moderate 3'09 3-23 Rain. 10 , ,t 10th 749.3 15'0 11'9 14.5 S.by W. Fresh 3'11 3-11 Very wet. Rain all day. 11 ) 12th 750.5 13'4 11'9 14-5 S.W. by W. Strong 3.09 3-10 Windy. and much min from the 11th to the 16th. 12 ,( 16th 752.3 14.7 1?.8 15.0 N.W.by W. Light 2-93 2-95 13 , 17th 753.1 13.9. 12'8 15.0 W.S.W. Fresh 3'12 2'94 Baryta -water ex- posed 6 hours. I CONTAINED IN SEA-AIR. The kindness of Messrs. Alfred Booth & Co. of Liverpool has enabled me to extend this enquiry to the air of the Atlantic. The following determinations mere made in the manner above described during a voyage to and from the Brazils. The four bottles C D E F employed in collecting the air were however of greater capacity containing respec- tively 7375 cb. c. 7620 cb. c. 7510 cb. c. and 7560 cb. c. By thus experimenting on a larger volume of air any variations in the quantity of atmospheric carbonic acid over the sea would of course be rendered more appreciable. On the return passage I was unfortunately unable to make more than one experiment at once accident having deprived me of all my bottles with the exception of E.Table 111 on the following page shows the results of these determinations. The mean quantity of carbonic acid in the atmosphere of the Irish Sea from 26 experimeiits is 3.082; in that of the Atlantic it is from 51 experiments 2.953 in 10,000 volumes of air ; the mean of the 77 experiments being 3-00. This result compared with the following numbers giving the amount of carbonic acid contained in land air 'shows that conthry to the statement of Lewy the air of the sea con-tains a much smaller proportion of carbonic acid than that of the land. The most extensive observations on land-air have given as means :-No.of Vols in Observer.Locality. Expta. 10,000 of air. Th. de Saussure Chambeisy .......... 104 4.15 Boussingault .. Paris ................ 142 3997 Verver ........ Griiningen .......... 90 4-20 Roscoe ........ London and hlanchester 161 3.95 Angus Smith .. do. do. 200 4.03 General mean of observations on Land-air ...... 4-04 General mean of observations on Sea-air (Lewy 11 independent experiments) ................. 4-63 General mean of observations on Sea-air (Thorpe 44 independent experiments) ................ 3.00 The quantity of carbonic acid contained in land-air is subject to continual alteratim from the variable circumstances of locality temperature fog rain &c.; it may thus vary from TABLE111. Showing the Amount in Volumes of the Carbonic Acid in 10,000 vola.of the Air over the Atlantic Ocean determined by Pettenkofer'a Nethod. Date. Ship's Position. Bar. Temp. of Air. Temp. Carbonic Acid. NO. Hour. of Wind. 1866. mm. Sea. 1st 2nd Lat. Long. Dry. Wet. Expt. Expt. __. --14 Feb. 26th 1I .38 p.m 3%i2 N fS.3) W 170'0 $5 6.0 18.7 N.W. by W. Gentle breeze 2.90 2.93 200 miles south of Madeira. Fine. 15 , 27th 5.24 a.m. 28'43 17'45 161'5 16'2 13'0 17.0 W.N W. Moderate 2.66 2.83 Off Palma Canaries. Cloudy. 16 , 27th 3.50 p.m. 2i.47 18'00 758-0 17.6 160 19.0 W. by S. Squdly 2.83 2'87 Off Ferro Canaries. Cloudy. 17 , 28th 3.19 p.m. 26'21 19'09 760.1 18'5 17% 19.2 do. do. 2,97 2.84 Rain. 18 March 2nd 3.40 p.m. 21'30 23.11 167'1 22'8 17.9 21-7 N. Very light 3.02 3.06 130 miles south of theTropic.Very finc. 19 , 3rd 5.15 am. '20'15 24'09 166'0 19.6 18.0 -S. do. 2.97 2.91 Sea calm and very phosphorescent. 20 9) 316 3.0 p.m. 19'17 24'51 166-0 26.0 21.0 22.0 Variable light airs 3-04 3 12 Calm. Baryta-water (Axposed 5 hours. 21 , 5th 4.40 a.m. 16-32 27'46 164.5 21.2 21 .o 22.0 N.I.:. Gentle breeze 3-13 5.36 Cloudy. Sea phosphorescent. 22 , 5th 3.10 p.m. 1432 28'26 7672 26'1 2.7'6 22.5 S.W. Light and variable 2'98 2'94 Fine and clear. 23 5th do. do. do. do. do. do. do. do. do. 3.07 2.96 Exposed 3 hours before titration. 11 24 9-6th 4.45 a.m. 13'12 29.21 567.1 21.8 21'7 22'5 Variable liqht breeze 2.83 2.82 Dark; cloudy. Sea phosphorescent. 25 1 6th do. drr. do. do. do. do. do. do. 2.96 2.91 Baryta-water exposed 2i hours. 26 99 6th 5.10 a.m.J 1'59 3n. I 2 764.5 23'5 21 1 23.5 Winds northerly. Gentle A -27 (9 7th 5.10 a.m. 10.48 31'03 766'5 23'3 20'0 22,5 N.E. by E. Gentle 2.97 2.93 Cloudy. Midway between Africa and . America. 28 $9 7th do. do. do. do. do. -do. do. 2.99 -29 It 7th 2.85 p.m. 9-50 31-39 766.0 Y4.2 21.7 24.5 E. do. 2-88 2.90 Cloudy. 30 19 7th do. do. do. do. do. do. do. do. 2.78 2'91 31 9s 8th 5.35 a.m. 5-34 32-37 766'5 24'2 21'1 24'5 S.E. Fine breeze 2.74 2.89 Daybreak. Sea phosphorescent during former part of night. 32 9 8th do. do. do. do. no. do. do. do. 2-71 2'69 33 77 8th 3.15 p.m. 6'49 33'03 760.1 25.6 22.8 25.5 E.N.E. do. -Cloudy. 34 , 12th 7.4.3 p.m. 3-125. 38.12 i62-5 29.5 26.1 27.2 Light air 3.09 3.01 Calm. 40 miles from Ceara. 35 , 12th ao. do. do. ao. do.-do. do. 3'02 3'12 36 , 13th 3.10 p.m. 3.43 38.34 76 1'3 28.0 26.0 29-0 N.E. Gentle breeze 3.06 2-98 Off Ceara. Very heavy rain immediately befor,. experiments. 37 July 16th 3.16 p.m. 15.14 N 26-13 563.5 26.2 22.8 24'5 N. Light bre?ze 2.94 -Uaryta-waterin all following experiments titrated by hydrochloric acid solution. sa , 17th 8 0 p.m. 18.21 24'45 564.0 23.9 22.5 23.0 E.byN. do. 39 , 18th 3.0 p.m. 20.09 23'48 l64-5 23'6 22.7 23'0 N.E. by E. Noderate -05 -40 ) 18th 6.40 1b.m. 20.28 23.36 i65'0 24'3 22.8 22'5 N.E. do. 3'05 Cloudy. 41 , 196h 3.15 p.m. 2225 22-45 766.4 25.9 22.8 22.5 N.E. by E. Erisk 3.13 -Pine and clear. 42 , 19th 9.0 p.m. 22.50 22-28 567.5 24.3 22.5 22'0 N.E. Fresh 3 09 43 , 2iXh 1I .15 a.m 23.43 21-37 7iO.O 26'1 22.8 22.2 N.E by E. Moderate 2'90 -Fine.44 , 21st 9.0 p.m. 26.19 I9.M 770.0 23'4 20.1 21.2 a0. do. 3'04 -180 miles S.W. of Ferro Canaries. 4s , 241h 7.30 a.m. 32% 14-38 77OV0 23'3 20'6 22'0 N. Light air 3.00 -Calm and sunny. 46 , 25th 10.4; a.m 39.56 13-05 7i3.5 23.5 -21'2 N.E. Gentle biecze 2.97 -Clear. 47 , 29111 8.0 p.m. 34.43 12.28 773-5 21.6 20-4 20'5 NE. Moderate 2.88 -Nidway between Madeira and Lisbon. -* CONTAINED IN SEA-AIR. 2.5 to 8 volumes in 10,000 of air. It mould appear however from the above experiments that the amount of carbonic acid in sea-air experiences fewer arid far less extensive variations ; it is sensibly the same in different latitudes and is constant in the same locality throughout the year. Thus the mean quantity of carbonic acid contained in sea-air between the parallels of 13" and 30" N.latitude was in the months of February and March 1866 2.96 in 10,000 volumes of air in July of the same year it was 3-00volumes. From Saussixre and B o us s in gan 1t 's observations a decided difference may be traced between the amounts of carbonic acid in the air of day and night on the land the air of the night containing more carbonic acid than that of the day in the proportion of 100 to 92 ; but from the following table it clearly appears that no such differences are to be discerned in sez-air TABLEIV. Showing Comparative Amounts of Carbo& Acid eontnined in Sea-Air during Day and Night. NO. Day. NO. Night. 1 2.87 2 2 -99 3 3 -14 4 3 -26 6 3.17 6 3.12 7 Y -17 8 3 001 9 3 -16 11 3 -10 10 3 .:1 13 3 03 12 2 94 15 2 75 14 2 -92 19 2 94 16 2 85 21 3 24 17 2 90 24 2 -83 18 3 .04 25 2 94 20 3 08 27 2 95 22 2.96 28 2 99 23 3 02 31 2 *82 29 2 89 32 2 .70 30 2 .85 34 3 *05 36 3 02 35 3 07 37 2 -94 43 2 90 39 3 *05 45 3 .oo 40 3 05 46 2 *97 41 3 *13 42 3 09 44 3 04 47 2 -88 Day.Night. Means ....,,... . .. 3 411 ...... 2.993 198 THORPE ON TE[E AMOUNT OF CARBONIC ACID The non-accordance of these results with those obtained hy Lewy is undoubtedly rnaiiily due to the difference in the methods of analysis employed. L ewy 's determinations were made in Regnault's eudiometer in which as is well known the volume of' gas is maintained constant throughout the analysis the relative changes being estimated by the variations in the pressure of that constant volume over or under that of the atmosphere measured in millimetres of mercury.Thus as Dr. Frankland has already pointed out (Chem. SOC.Journ. vi 199) a variation in volume which in the older method of Bun sen would appear considerable is in that of Regnault only represented by a small numerical expression. This may be clearly illustrated by an actual determination by L e wy of the amount of carbonic acid in the air of Havre made at Bogota 2,645 metres above the sea level (loc. cit. p. 190). Tempera-Tempera-:i:e; Large tube ture of ture of Barometer. wire. (open). water in cylinder. bsrometer. I-m.m. m. m. m. Air dried (moist) . . . . .440.00 226 92 15O.65 15"-50 0 -56090 After absorption of car-bonic acid by potash (moist). . . . . . . . . . 440 -00 226 .DO 15O.65 15"*50 0 .ti6080 I I Carbonic acid in 10,000 vola. of air 3.586. Let us now suppose that an error of of a niillimetre had been made in the first observation and that thus the corrected pressure appeared to be 334.67 mm. instead of the actual amount 334.58 mm. then the amount of carbonic acid would have risen to 5.996 or a difference would occur in 10,000volumes of air of 1-51 vol. The greatest difference observed by Lewy between the amouiits of carbonic acid contained in the air of day and night over the sea is 2.074 volumes in 10,000 of air. It deserves also to be noted that Lewy's analyses were not made until eighteen or twenty months after the air had been col- lected ; and although L ewy satisfied himself by experiment that air contained in glass tubes for such a length of time ex- periences no alteration in composition yet Regnault* has * Ann.Ch. Phgs. [31 xxxvi 392. CONTAINED IN-THE ATMOSPHERE OF TROPICAL BRAZIL. 'bog subsequently shown that the exact determination ofthe amount of atmospheric carbonic acid cannot be made in air thus pre- served since the glass absorbs a portion of the gas. The main conclusions therefore to be drawn from the fore- going experiments are :-1. That the sea does not act in increasing.the amount of atmospheric carbonic acid. 2. But that on the contrary the air over the Bea contains a much smaller proportion of carbonic acid than the air of the land although the influence of the $ea in abstracting this gas from the atmosphere is not so great as the older experiments of V o g e 1 and K r u g er would indicate.3. That the mean quantity of carbonic acid contained in the normal atmosphere of the ocean is 3.00 in 10,000vols. of air. 4. That this proportion is constant or nearly so in &.fY;ereiit latitudes. 5. That this proportion is not sensibly influenced by the different seasons of the year. 6. That this proportion does not experience any perceptible diurnal variations.

ISSN:0368-1769    

DOI:10.1039/JS8672000189

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

CONTAINED IN-THE ATMOSPHERE OF TROPICAL BRAZIL. 109 XVII1.-On the Amount of Carbonic Acid contained in the Atmod-phere of Tropical Brazil during the Rainy Season. By T. E. THORPE. THEfollowing determinations of the amount of carbonic acid contained in the land air of the tropics were made at Par& This town is the principal port of entrance to the Amazons and is situated about eighty miles from the sea on the river GrUaru-Parii in lat. lo 27’ S. and long. 48’ 28’ W.; it is built on the verge of a vast primeval forest extending to the sea-coast and over which the trade winds of the Atlantic regularly blow during the greater part of the year. These determinations were made by Pettenkofer’s methodin the marmerpreviously described (p. 192). Hydrochloric acid was substituted for oxalic acid in the titration of the baryta-water since solutions of the latter acid decompose rapidly in the tropics.The follow- ing table gives the results of these determinations. 200 THOWE ON THE AMOUNT OF CARBONIC ACID ETC. -TABLEV. CO in Temp. of 10,000 vols. Date. Bar. Air. of Air. No. Wind Brc. 1866. Hour. mm. 1st 1 2nd DV. Wet. Exyl Expt 1 hpril3rd 4.20 p.m. 762.0 23-4 23.1 Light air; overcast 3-19 3.14 After 6 hours' heavy and almost incessant rain. ,$ 4th 3.0 p.m. 761.4 29-0 27.5 Little wind ; gloomy 3'44 3'35 Imniediateiy previous to a rtonn. 3 , 16th 11.20 a.m. 766-0 30'1 26-2 N.E. Light breeze 3'47 -Much ruin on previous night cloudy. 4 , 16th 3.45 p.m. 163-5 25'6 24.7 N.E.Gentle breeze 3-22 3.13 After 14 hrs. heavy rain. 5 , 18th 9.25 a.m. 16ii.0 27.2 25-0 N.E. Little wind 3'27 3-12 Cloutly ; dull. 6 , 18th 3'5 p.m. 763.5 25'9 25.3 -3-22 -After lain. 7 , 19th 2.30 p.m. 162.5 28.9 25.6 N.E. by E. Fine breeze 3'30 3.12 Sunny. 8 , 218t 12.50 p.m. I 64'0 33'3 26.6 N.E. Gentle breeze 3'41 3-28 Fi. e. 9 , 23rd 1.20 p.m. 264-5 28-3 25-9 do. do. 3'12 5-27 Fine and sunny. 10 24th 2.35 y.m. I 64-0 32.3 25.6 do. 3'16 3-48 Clear. 11 diy 4th 2.50 1i.m. 763.3 29 6 211.6 N.N.E. Fine breeze 3'32 -Fine. 12 , 7th 3.30 y.m. 762.0 26.9 24'6 Variable and light 3'07 3.14 Gloomy. 13 , 12th 1.40 y.m. 761'5 27'4 25-6 N.N.E. Fine breeze 3.24 3'35 Glooniy. Immediately before storm of wind and rain. 14 , 18th 11.15 z63-5 30-8 25% N.E. Gentle breeze 3'32 3-28 15 , 21st 12.45 8 62.5 29.8 25'6 N.E.3-31 3'29 Fine and sunny. 16 , 23rd 11.45 764'5 32'2 27'2 Fine breeze 3'45 3-32 Cloudy. 17 , 26th 1.0 764'5 31.i 25'0 Fresh breeze 3'49 330 1 ittle rain for past three --days. Fine. From the above 31 exDeriments it amears that the mean 1 II qwntity of carbonic acid contained in the air of tropical Brazil during the months of April and May 1866 was 3-28 in 10,000 volumes of air-a very marked difference from the mean pro- portion (4.0vols. in 10,000 of air) contained in the atmosphere of Europe and probably due in great measure to the joint actioir of tropical rain and tropical vegetation in withdrawing this gas from the air. The influence of rain on the amount of atmospheric carbonic acid is well known from the experinients of Sa u ssu r e and Bousingault.The annual rainfall at Par6 is very heavy amounting according to observations kindly furnished to me by Drs. Bruno-Cabral and Jose Abrea to nearly three metres (118 inches) of which about one-third falls during the months of March April and May. The above determinations are consequently interesting as showing the proportion of car-bonic acid in the atmosphere of the tropics in the middle of the rainy season of the year. The amount of carbonic acid contained in the atmosphere of the tropics during the different seasons of the year has already been determined by L ewy". The mean of an extengive series of analyses of the air of Bogota,in New Granada during the wet and dry seasons of the year is as follows :-# Loc. cit. p. 190. MATTHIESSEN ON ALLOYF. During the During the rainy 0ea00n. dry season. Carbonic acid in 10,000vols. of air 3.822 4,573 In conclusion I beg to tender my thanks to Profesaor Roscoe for the valuable advice and assistance he has given me during these investigations.

ISSN:0368-1769    

DOI:10.1039/JS8672000199

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

MATTHIESSEX ON ALLOYS. X1X.-On AZloys. By A. MATTHIESSEN,F.R.S. Lecturer on Chemistry in St. Mary’s Hopital Medical School. [B Discourse delivered to the Fellows of the Society February 7th 186’7.1 IN the following pages my object besides drawing attention to the general nature and properties of alloys is to phow reasons deduced from experiments for my adoption of certain views on the subject which may be summed up in a few words thus :-I. That according to certain physical properties the metals may be divided into two classes :-Class A. Those metals which impart to their alloys their physical properties in the proportion in which they themselves exist in the allby. Class B. Those metals which do not impart to their alloys their physical properties in the proportion in which they them- selves exist in the alloy.The metals belonging to class A are lend tin zinc and cad- mium and those belonging to class B in all probability all the rest. 11. That the alloys may be divided into three groups :-a. Those made of the metals belonging to class A with one another. b. Those made of the metals belonging to class A with those of class B. c. Those made of the metds belonging to class B with one another. 111. That in nearly all cases the two-metal alloys may be considered as solidified solutions of the one metal in the other. Under the term solidified solution I mean a solution of two 20% MATTBIESSEX ON ALLOYS. substances which has been allowed to solidify as for instance if a mixture of ether and alcohol were made and sufficient cold could be produced to solidify it we should produce a solidified solution of these two Substances in one another.Again if the chlorides of potassium and Sodium say in equal parts be melted together and allowed to solidify the solid thus produced is a solidified solution of the chlorides of potassium and sodium in one another. Glass is also a good example of a solidified solu-tion ; to produce it different silicates are fused together and allowed to solidify. There is however an important point in the definition of the term solidified solution which must not be overlooked namely that the components are most intimately mixed together ; in fact they are homogeneously diffused in one another and to that extent that even under the most powerful microscope it would not be possible to distinguish the compo- nents of a solidified solution.As examples of this fact glass may be quoted which presents under high magnifying power a homogeneous mass ; the silver and gold in the gold-ailver alloys cannot be distinguished by the same test from one another. Such then is a brief outline of what I consider alloys generally to be and I will now proceed to explain why I have adopted these views; but before elitering on the subject I would state that what I am about to say regards only two-metal alloys made from pure metals. I make this remark as some of the facts I am about to advance do not agree with those generally accepted. A most useful piece of apparatus in inabing alloys for experi- mental purposes on a small scale is the common clay tobacco pipe the bowl serving for a crucible and the stein as a means of passing a gas (hydrogen) through it to mix the melted metals to prevent oxidation and afterwards a8 a form to cast the alloy in by sucking the contentfi of the bowl into the stem by means of an india-rubber tube.This form of apparatus might be made in any size in fire-clay and would be of great service in experimenting with copper and its alloys. If to a melted metal a solid one be added certain phenomena will be observed which may be classed under the followiiig heads I. The solid metal dissolves quickly in the melted one with evolution of heat notwithstanding the fact that a cold piece of metal is put into the fused one and also that a certain amount XATTHIESSEN ON &LOPS.203 of heat is rendered latent by the liquefaction of the solid metal; a8 examples gold ancl just melted tin; sodium and mercury. 11. The solid metal dissolves quickly without evolution of heat ; as example lead and just melted tin. 111. The solid metal dissolves slowly; as example copper and just melted tin. IV. Only a partial alloy is formed or in other wordx each metal dissolves to only a limited extent in the other in the same manner as ether and water for water will only dissolve a certain amount of ether and ether a certain amount of water. Now supposing these solutions were well shaken ~ip together and submitted to an intense cold sufficient to solidify them the solid mass so produced wonld.not be a solidified solution of ether and water but a mixture of solidified solutions of ether in water and water in ether for no doubt under a high magnif~ng power the componeiits of the mixture could be distinguished one fiom the other. Perfectly analogous cases are found with alloys as examples I. Lead and zinc lead will only dissolve 1.6 per cent. zinc zinc only 1-2 per cent. lead. 11. Bismuth and zinc bismuth mill only dissolve 8.14 per cent. zinc and zinc 2.4 per cent. bismuth. These facts may be easily proved by fusing lead or bismuth in a crucible and adding zinc to the melted metal when after the addition of a certain quantity the zinc alloy being specifi- cally lighter will float on the surface; or better still if say equal parts of the metals be taken fused mixed thoroughly and cast into a mould imbedded in red hot sand and allowed to cool slowly the separation of the two alloys mill be perfect.If on the contrary equal parts of the two metaIs be fused together well mixed and cooled suddenly such an niloy would be analogous to the case of ether and water a mixture of solidified solution of zinc in lead or bismuth and of bismuth or lead in zinc. The physical properties of alloys may be divided into thee classes :-I. Those which in all cases are imparted to the alloy approui-mately in the ratio in which they are possessed by the compo- nent metals. 11. Those which in all cases are not imparted to the alloy in the ratio in which they are possessed by the component metals.WATTHIESSEN ON ALLOYS. 111. Those which in some cases are and in others are not im- parted to the alloy in the ratio in which they are possessed by the component metals. From the last class I shall endeavour to deduce the chemical nature of alloys; it will however be necessary to say a few words regardiiig the other two classes. As types of the first class specific gravity specific heat and expansion due to heat may be taken. a. Specijc Gravity.-With regard to this property. it is too well known that the specific gravities of the metals take part in t,hat of their alloys approximately in the ratio of their relative volumes to need any further comment ; but for the sake of illus-tritt.ion I give the following tables the first containing the values found for the specific gravity of alloys of two metals belonging to class A and the second those of two metals belonging to class B.TABLEI. Sn .......... Obs. specificgravity. 7-295 T. 12.8 Cal. specificgravity.- Sn,Pb ........ 7.927 15.2 7.948 Sn,Pb ........ 8-188 16-0 8.203 Sn,Pb ........ 80.77 9 17.2 8-781 SnPb ........ 9.460 15.5 9.474 Sn PI+ ....... 10-080 14.8 10.136 Sn Yb,. ....... 10.590 14.3 10.645 Sn Pb&....... 10-815 15.6 10.857 Pb .......... 11.376 13.5 - TABLE11. Ag .......... Obs. specificgravity. 10.468 T. 13.2 Gal. specificgravity.- Ag,Au ...... 11.760 13.1 11.715 Ag,Au ...... 12.257 14-7 12,215 Ag,Au ......13,432 14.3 13-383 AgAu ...... 14.870 13.0 14.847 AgAu ...... 16.354 13.0 16.315 AgAu ...... 17.540 22.3 17.493 AgAu ...... Au .......... 18-041 19.265 13.1 12.8 17.998 - (Pld. Trans. 1860 p. 177.) XWTTHIESSEN ON ALLOYS. b. Spec$% Heat.-In the few caseR in which experiments hare been made on the specific heat of alloys it appears that the specific heats of the metals take part in that of their alloys in the ratio of their relative weights as shown in table 111. TABLEnr. Obs. specific heat. Cal. specific heat. PbSn .......... 0.04073 0.04039 PbSn .......... 0.04506 0.04461 PbSb.. .......... 0-03880 0-03883 BiSn. ........... 0-04000 043987 BiSn .......... 0.04504 0.04415 (Watts’ Dict. Chem. iii. p. 33.) This may easily be shown with the help of an inverted differential thermometer (figure I) the construction of which DIFFERENTIAL THERMOMETER.- C needs no explanation. The stop-cock a has been found most useful in adjusting the level of the liquid in the bent tube. If an alloy be made (say gun-metal) and cast in a mould and if on the other hand a piece of copper be cast in the same mould and turned down so that its weight corresponds to the weight of copper in the alloy ; and if the amount of tin corresponding to the quantity of tin in the alloy be cast round the top of the copper two castings will be produced (b and c figure 1) of equal weights the one being an alloy the other its components. These may now be heated in boiling water for a short time and then placed in the cylinders (d d) into which equal weights or bulks of water of the same temperature have been poured and VOL.xx. Q MATTHIESSEN ON ALLOYS. if after about a minute's immersion during which time the castings have been kept in motion the air-thermometer be placed in the water no difference in the level of the liquid will be observed indicating that the specific heats of the two castings are the same. On the contrary if equal weights (about 500 grms.) of two metals having different specific heats be taken for instance lead and zinc and if the same process be followed out a very marked difference will be observed in the indication of the thermometer (about 60 rnm. difference in the levels of the liquid in the bent tube).If however weights of any two metals be taken corresponding to their combining numbers no difference in the heights of the columns will be observed. This modification of the differential air-thermometer is a simple means of illustrating many experiments on heat a# for instance latent heat influence of sources of heat and of salts on the boiling points of liquids showing that the temperature of steam is not altered by the addition of salt to the water (the practical application of this well known fact is seen in fixing the boiling point of a thermometer) &c. c. Expansion due to Heat.-That thisproperty also follows the law namely that the expansion due to heat of the metals takes part in that of their alloys approximately in the ratio of their relative volumes is proved by the results given in table IV.TABLE IV. Observed Calculated Alloy. Sn,Pb.. .............. Volumeg percent. 22-28 Pb volume at 0" = 1 v. at 100'. 1.007188 yolume at 0" = 1 v. at 100". 1 -007 2 25 Pb,Sn.. ................ 82.09 Pb 1.008419 1*008129 CdPb .................. 58-49 Pb 1.009 138 1-008847 Sn,Zn .................. 87.46 Sn 1*007184 1-007 144 Sn,Zn .................. 91-28 Sn 1-007058 1*007066 Bi,,Sn.. ................ 0.85 Sn 1.004064 1*003972 BiSn .................. 42-81 Sn 1*005098 1*005207 Bi,,Pb .................. 1.76 Pb 1*004086 1.004026 BiPb .................. Cu + Zn (71 p. c. Cu) .... AuSn .................. 46.26 Pb 33-85 Zn 60-85 Sn 1-008 621 1*005719 1a04233 1~006007 10006328 1.005919 Au,Sn .................73-14 Sn 1.004428 1.006223 MATTHlESSEN ON ALLOYS. TABLE IV (continued). Ag4Au.................. 19.86 Au 1.005166 10005549 AgAu .................. 49.79 Au 1-004916 1.005123 AgAu,. ................. 79-86 Au 1.004300 10004693 Ag + Pt (66.6 p. c. Ag.) .. 19-65 Pt 1.004568 1*005207 Au + Cu (66.6 p. c. Au) .. 48.06 Au 1.004657 1:004716 Ag + Cu (36.1 p. c. Ag) . . 28.31 Ag 10005436 1.005233 Ag + Cu (71.6 p. c. Ag) . . 73.13 Ag 1*005713 1.005607 A simple mode of showing this is to take a bar of gun-metal and place it as shown (fig. 2.) in a glass tube fitted at the ends with glass tubes in such a manner that steam can be blown through it. If now a comparative experiment be made in this manner fist with a bar of gun-metal and then with a bar made of its components by Roldering together the proper lengths of copper and tin as shown in the figure it will be found that the index indicating the expansion will show in both cases the same readings.APPABATUS BY HEAT. TO SHOW EXPANEIION 11. As types of the second class of physical properties namely those which in all cases are not imparted to the alloy in the ratio in which they are possessed by the component metals the fusing points and crystalline form may be chosen €or discussion. u. Fusing Points.-It has been often stated that the fact of the fusion point of an alloy being lower than the mean fusion points of the component metals is an indication of chemical com-bination. But on carefully looking into what is known on the aubject it will be found that all mixtures have a lower hsion point than the mean of the substances forming the mixture.So for instance salt water solidifies below zero; chloride of potawium and chloride of aodium fuae at a lower tern-Q2 MBTTHIESSEN ON ALLOYS. perature than the mean of the relative volumes of the coin-ponents so likewise do mixtures of chloride of potassium with chloride of calcium or strontium &c. As a practical example of this fact the fluxes used by metallurgists may be quoted; so also the solder used by various metal-washers ; and when decomposing a silicate we prefer to fuse it with a mixture of the carbonates of potassium and sodium rather than with either of them alone.Taking the most simple of these cases the mixture of the chlorides of potassium and sodium I may say that nobody has as yet asserted in this case that chemical combination exists between these salts on account of the existence of a lower fusion point than the mean fusing point of the component salts. This property being a general property of all mixtures (some of the amalgams I believe only excepted) we must arrive at the conclusion that the fact that alloys fuse more readily than the mean fusing points of the component metals is by no means an indication of chemical combination. This fact I think admits of explanation as follows :-It is generally admitted that matter in the solid state exhibits excess of attraction over repulsion whilst in the liquid state these forces are balanced and in the gaseous state repulsion predominates over attraction.Let us assume that similar particles of matter attract each other more powerfully than dissimilar ones. It will then follow that the attraction sub- sisting between the particles of a mixture will be sooner over- come by repulsion than in the case of a homogeneous body hence mixtures should fuse more readily than their con- stituents. b. Crystalline Form.-Various observers have deduced that certain alloys are chemical combinations owing to their crystal- lising in definite forms; this has also been often done in the case of carbon-iron alloys ; in fact numerous chemical combina- tions between these two elements have been said to be discovered in this manner.It may however be asserted that definite crystalline forms with alloys are not necessarily chemical combinations. Cooke was I believe the first to point out this for he proved that all the alloys of antimony and zinc containing from 43 to 64 per cent. of zinc crystallise in the same form but differ- ently from the other alloys of these two metals. With the JUTTHIESSEN ON ALLOYS. 209 gold-tin alloys it has been shown that well defined crystals are not limited to definite proportions of the two metals but are common to all alloys of these metals containing from 27 to 43 per cent. gold. The crystals of these alloys have never the same composition as the mother-liquor from which they were crystallised but contain always more gold as is shown by the results contained in table V.TABLEV. A mount of Amount of Amount Of Composition gold per cent. gold per cent. g of alloy. in first crop ~ ~ d ~ ~ ~ ~ ~ of crystals. in liquor. 2nd crop. 43 *6 43-6 40.8 1 6th crop. 42.9 38 -7 4th crop. 37-5 Au 39-7 37 -6 32 '9 62.6 Sn } 4th crop. 35 -0 Au 32 *6 30 *6 65-0 Sn } 4th crop. 32 -5 Au 35 2 28 -7 67-5 Sn } -_I_ 6th crop 30-0 Au 31.5 25 -3 70.0 Sn } Storer has also shown that all the copper-zinc alloy8 crystallise in the same form so that crystals of any composition can be obtained. In considering this property we must bear in mind the influence of traces of foreign matter on the crystallisation of all substances.Thus many pure metals may be made to crystal- lise more readily if a trace of another metal be added; for instance antimony to which a trace of tin k added MATTHfESSEN ON ALLOYS. crystallises much rriore readily and in much larger crysta.ls than the pure metal. With lead the case is reversed for in this case the purer the lead the larger the crystals. With salts we find analogous behaviour; so for instance chloride of ammonium when dissolved in pure water crystallises in small crystals but when a small quantity of tarry matter is added to the solution it crystallises readily in large cubes; common salt crystallises from water as is well known in cubes ; from urine or from water containing urea in octohedrons. The fact that two metals are capable of alloying with each other and producing definite crystalline forms in other pro- portions than those of their combining weights ought always to be borne in mind when discussing the chemical nature of a metallic compound.111. As types of the third class of physical properties namely of those which in some cases are and in others are not imparted to the alloy in the ratio in which they are possessed by the component metals the conducting power for heat and electricity sound elasticity and tenacity may be taken. a. Conducting Power for EZectricity.-The values obtained for the conducting powers of alloys prove that this property belongs to this class. Table VI contains the values employed in calculation. TABLEVI. Specific conducting Metal.All hard-drawn. Atomic weight. Specificgravity. power of metre length and millimetre diameter in terms of the BA unit. Silver .... 108 10.5 4795 Copper. ... Gold.. .... 63.5 197 8.9 19.3 47.5 37.1 . zinc..*... 65 7.1 13.8 Cadmium.. 112 8.6 11.3 Tin ...... 116 7.3 5.9 Lead.. .... 207 11.4 4.0 Iron. ..... - - 8.0 Tables 7 8 and 9 contain a few examples of each group ot alloys. Table 7 those of class A with one another. Table 8 those of class A with class B. Table 9 those of class B with one another. TABLEVII. Specificconducting power of metre length and millimetre diameter in terms of the BA unit. Alloy. Sn4Pb ...b Sn,Cd .... Sn,Zn .... PbSn .... ZnCd . . . . Sncd .... CdPb ... . , Volumes per cent.83.9 tin 83.1 ,? 77-7 , 534 lead 26-1 zinc 23-5 tin 10.6 cadmium \ \ Observed. Calculated. 5.7 5.6 6-9 6.8 7.9 7.6 4.8 4.9 12.2 12.0 10.3 10.0 4.3 4.7 5.7 8-5 6.0 12.7 4.2 41.3 5.9 42.7 9.4 45.0 297 46-9 10.4 33-3 10-3 37-6 13.4 39.6 22-1 43.9 28-7 45-8 10.1 39.2 7.1 42-1 10.3 45.4 26.7 37-3 7.6 39.0 9.8 45.5 40.0 47-4 6.3 -AII hard-drawn. Copper-tin .... ? .... 99 .... ?? .... 1 .... 99 .... Copper-zinc.... ?9 .... Yf . . .. ? -.. 9 .... All hard-drawn. Gold-silver . .. .... Y? .... I? Gold-copper.. .. .... 91 *... $9 .... 9) Steel ........ TABLEVIII.93.6 tin 83.6 , 14.9 , 11.6 , 6.0 ,I 1-4 9 42.1 zinc 29.4 ,? 23-6 , 10.9 , 5.0 79 TABLEIX. 79.9 gold 52.1 ,, 19.9 , 98.4 , 81.7 , 19.2 , 0.7 $9 The accompanying curves 1 2 and 3 represent graphically the values obtained for the conducting powers of some alloys of each group the conducting power of ailver being taken for convenience sake to equal 100. 212 MATTHIESSEN ON ALLOYS. 1 Volumes per cent. Copper 8 E B E. I Ld P 9 Volumes px cent. 2 Volumes per cen?. Cadmium Tin Volumes per cent. MATTHLESSEN ON ALLOYS. 3 Volumes per cent. Silver Copper -Volumes per cent. From these it will be seen ant a glance that the alloys belong- ing to metals of the class A conduct electricity in the ratio of the relative volumes of the component metals whilst the others do not.It will be as well to draw attention at once to the marked change which takes place in this property when a metal belonging to class B is alloyed either with one of its own class or with one belonging to class A; and also to the fact that when a metal belonging to class A is alloyed with one of class B. no such change takes place. This behaviour is observed with all the physical properties belonging to this class. b. Conducting Power for Heat. -Wiedemann and Franz have shown experimentally that the conducting powers for heat and electlicit-y for metals and alloys are identical. The conducting power for heat may be conveniently shown with the heTp of the apparatus represented in fig.3. If bars of copper copper-tin alloys of various compositions and tin be made and fitted in the box as shown in the figure with amall air-thermometers at their ends and boiling water be poured into the box (which may be kept boiling with lamps under-neath) the depressions in the column^ of liquid h the air- 214 MATTHIES6EN ON ALLOYS. thermometers will approximateIy show the ratio between the conducting powers of these bars. An additional advantage of thb modification of the apparatus is that the differences of the APPAXATUS TO SHEW CONDUCJTIVITY OF METALSAND THEIB ALLOYSFOB HEAT. ELE VA TI3N 5EC I I ON. indications of the thermometers remain constant for Borne time The cme formed by the tops of the columns would represent in fact the resistance-curves for electricity.It is obvious by taking series of the other two groups of alloys the indications of the thermometers would give the resistance-curves corresponding to those allop. This method gives us therefore a simple and striking means of showing the audden or gradual alteration in conductibility in the three groups of alloys. It is scarcely necessary to mention that screens must be placed between the box and the air-thermometers to prevent the thermometers being heated by radiation. c. Sound.-If bars of copper tin zinc or lead suspended by a string be struck they all emit a dead sound; if on the con-trary bars of copper-tin (gun-metal) or copper-zinc (brass) be struck they will emit a clear ringing note showing the marked effect of alloying a metal of class B with one of class A.Conversely if we strike bars of tin-copper (containing 12 p. c. copper) or tin-lead (containing 20 p. c. lead) they will emit a dead sound showing? as in the cases of conduction of heat and electricity no marked change when metals of class A are alloyed with one another or with one belonging to class B. The same effects will be produced when bars of wrought iron and steel aae struck the .first emitting only a slight sound the second a clear ringing note. d. EZastieity.-When a weight is hung to spirals of hard &awn wires of the same diameter both in wire and coil different effects will be produced (diameter of wire No.23 wire-gauge diameter of coil about 7 mm. weight used 300 grms.) MATTHIESSEN ON ALLOYS. The copper silver gold and platinum spirals will be almost lengthened to a straight wire. The tin zinc copper-tin (12 p. c. copper) and tin-lead spirale dl be almost lengthened to straight wires with only 50 pst The copper-tin (gun-metal) brass platinum-silver (33 p. c. platinum) and gold-copper (22 carat) spirals will be only lengthened to a small extent with 500 grms. The iron spiral may be made to lengthen with 500 grms. weight especially on shaking the spiral; but that of steel does not lengthen at all under the same conditions. Here then again we see the marked change in this property when a class B metal is alloyed with one of its own class or with one of class A as well as the absence of a.nymarked change when a class A metal is alloyed either with one of its own class or with one of class' R.e. Tenacity.-With the help of a draw-bench and sphg-balance wires may be broken to show in a rough way their relative tenacity. The values in the followillg table must be considered as only approximative but they will neverthelem lshow the fact that as soon as a metal beloaging to clam B is alloyed with another its tenacity is greatly increased. All hard-drawn wires gauge No. 23; for convenience sake double wires were used in the experiments. TABLEX. Breaking strain for double wire. Copper.. ................ 25-30 lbg. Tin ....................under7 , Copper-tin (12 p. c. tin) .. 80-90 , Tin-copper (12 p. c. copper) about 7 , Lead .................. under 7 , Tin-lead ................ 7 9, 99 Gold. ................... 20-25 lbs. Gold-copper ............ 70-75 , Silver .................. 45-50 9 Platinum. ............... 45-50 , Silver-platinum .......... 75-80 , Iron .................... 80-90 , Steel .................. above 200 lbs. The foregoing experim-ents tend to prove that the physical MATTHIESSEN ON ALLOYS. properties belonging to this class follow the law ; that as soon as a metal belonging to class B is alloyed with one of class A or with one of its own class a very marlred change in the physical properties takes place they no longer being equal to the mean of the relative weights or volumes of the component metals.That the curves representing their numerical values would have analogous forms is proved not only by the foregoing data but also by the fact that the turning points of the electric con- ducting power curves represent approximately the composition of technically used alloys such alloys being used on account of some special physical property. Thus gun-metal (10 p. c. tin) is marked on the copper-tin curve its turning point corresponding to 12.5 p. c. tin. Brass containing 28 p. c. zinc is marked on the copper-zinc curve the turning point of which corresponds to 25 p. c. zinc. 22 carat gold alloyed with silver is marked on the silver-gold curve and the same alloyed with copper on the copper-gold curve.When the Electrical Standard Committee appointed by the British Association arranged their unit-coil they chose the alloy containing 33 p. c. platinum on account of its being the turning point of the silver-platinum curve and from its possessing certain electrical properties which rendered it emi-nently fit for the purpose. It was afterwards found that this alloy had been in use for many years on account of its high elasticity as a dental alloy. The question now arises what are the alloys at the turning points of these curves? Are they chemical combinations or are they not and if not what are they? If they are chemical combinations then we lshould have to accept the followiiig formuls :-The alloy composed of 87-5 copper and 12.5 tin would correspond to about.................. Cu,,Sn The alloy composed of 75 copper and 25 zinc to Cu,Zn The alloy composed of 22 gold and 2 silver to .. Au,Ag The alloy composed of 22.1 gold and 2 copper to Aul,Cua The alloy composed of 66.6 silver and 33.3 plati-num to .................................. 4% ,Pta The alloy composed of 99.3 bismuth and $0.7tin to Bi,,Sn The alloy composed of 98.0 bismuth and 2.0lead to Bi,,Pb MA'I'THIESSEN ON ALLOYS. 217 The above alloys represent the turning points of the electric conducting power curves expressed in weights. Now it has just been pointed out that the curves which would numerically represent the third group of physical properties would have analogous but not identically the same form hence it follows that the turning points of these curves may vary several per cent.in their composition Are then these also chemical coin- binations? I think however that the idea of the existence of chemical combinations at these points must be given up owing to such abnormal combinations as the above which must then exist and also owing to the immense number of them having nearly the same composition as the curves representing each of the physical properties of the third group having in all pro- bability slightly diflerent turning points ; and if in the one case they be chemical combinations why should they not be in the other ? The great similarity in the forms of the curves representing the electric conducting powers of alloys spesks also against the turning points being chemical combinations :-for with the fkst group of alloys they are nearly straight lines; with the second there is a rapid decrement on the side beginning with the metal belonging to class B ; and then it turns and goes in a straight line to the metal belonging to class A.The letter L would represent the typical form of these curves ; and with the third there is a rapid decrement on both sides of the curve the turning points being connected with each other by nearly straight lines; the letter U would represent the typical form of this class of curves. Having thus shown the probability of the non-existence of chemical combinations at these points the next step is to indi- cate the probable cause of the marked changes in the physical properties of a class 13 metal when entering into an alloy.The experiments detailed tend to &ow that the third group of physical properties of the metal belonging to class B when it enters into an alloy with one of its own class or with one of class A undergo LL change and this change is brought about by a small quantity of the other metal the quantity of metal required for the completion of this change being dependent on the metal employed; in other words the class B metal enters into an alloy in an allotropic condition which modification possesses other physical properties than the original znetal MATTHIESSEN ON ALLOYS. krther when a metal belonging to class A enters into an alloy it retains in the alloy its original physical properties.If the turning points of the curves be now examined from the above point of view the following facts may be deduced. Taking the copper-tin copper-zinc bismuth-tin and bismuth- lead turning points as examples table 11 containrJ the numeri- cal data for these alloys. TABLEXI. Conducting power of alloy in terms of the B.A. unit for metre Composition of Alloy. lengthand millimetre diameter. ~~ Copper.. .. 0851 Tin.. .. 0149 4.19 ? .... *706 Zinc .. *294 10.33 Bismuth .. 09905 Tin .... -0885 0.117 9 .. *982 Lead .. *018 0*122 From the abol-e hypothesis the metals lead tin and zinc enter into alloys with their normal physical properties :hence the part these metals take in the conducting power of the above alloys may be calculated and will be found for tin in the first alloy tc be equal to 0.88 for 5-88 x -149 = 0.88.For zinc in the second alloy it will be found equal to 49C For tin in the third alloy it will be found equal to.. *OX For lead in the fourth alloy it will be found equal to *0715 the conducting powers of these metals being in terms of the B.A. unit equal to tin 5.88 lead 3.96 and zinc 13.80. With the first alloy the conducting power for allotropic cop- per may be found by subtracting the value found for the tin in the alloy from the conducting power of the alloy itself the value then for the 451 of copper will be found. Thus 4*19-0*88 = 3.31 this last value representing -851 allotropic copper; or a wire of a metre length and millimetre diameter of allotropic copper will have a conducting power equal to 3.89.From the copper-zinc alloy the value of *706 copper will be found equal to 6-27; or 1metre &c. copper haa a conducting power equal to 8.89. From the bismuth-tin alloy the value of -990 bismuth will be found equal to 0.0670; or 1 metre &c. bismuth has a conducting power equal to @0677. MATTHIESSEN ON ALLOYS. From the bismuth-lead alloy the value of -982 bismuth will be found equal to 0.050; or 1 metre &c. bismuth has a conduct- ing power equal to 0.0520. The conlucting power of the allotropic copper when alloyed with tin is found to be 3-89 and when with zinc 8-89. Now at first sight there seems no connection between these numbers but when they are divided by the conducting powers of tin and lead respectively the quotient will be nearly the same :-3.89 --0-662,and 8.89--0.644.5-88 * 13.8 If the values deduced for the conducting powers of bismuth be divided in like manner by those of tin and lead the same result will be obtained thus :-0.0677 -= 0.00115 and O.O,52' = 0*00130. 5-88 3-96 These values agree together as well as can be expected considering that the turning points have not been absolutely determined and that a small percentage difference will account for the differences between them. It may therefore be supposed although it has been only proved in these two cases that when copper or bismuth enters into an alloy their conducting powers alter as follows :-The conducting power of copper will be = 0.65 x the c.p.of the metal alloying it; and that of bismuth = 0*00123x the c.p. of the metal alloying it. What the above empirical deduction means I am at a 1068 at present to understand but the dataLI am at present acquiring will no doubt throw some light on the subject. From the above point of view most of the alloys made of metals of class A with one another may be regarded as :-Solidified solutions of the one metal in the other. Those made of class A with those of class B (say equal parts) as- Solidified solutions of the allotropic condition of the class B metal and the class A metal in one another. And those of class B (say equal parts) with one another as- Solidified solutions of the allotropic conditions of the one metal in that of the other.In the description of the foregoing experiments in connection with the third class of phyrjical propertiea it will be Been that MATTHIESSEN ON ALLOYS. I have always made a comparison between iron and steel. This has been done to show that the carbon-iron alloys behave in an analogous manner to other alloys which cannot be looked upon as chemical combinations. Now although many are of opinion that because the carbon in some sorts of cast-iron can under' certain conditions be evolved as carburetted hydrogen there exists between these two elements chemical combinations it is more than probable that the carbon when in the fine state of division in which it must exist in such specimens if they be solidified solutions may possess properties which do not belong to it in its denfier form.It seems almost inconceivable that chemical combination between two elements should simply be dependent on the various rates of cooling for it is possible to produce with some specimens so-called chemical cornbina- tion of carbon and iron (white iron) or the mechanical mixture of carbon and iron (grey iron) merely by cooliiig the molten mass quickly or slowly. The analogy of cast-iron and steel with other alloys indicates the non-existence of chemical com- binations between carbon and iron.* There seems to be but little doubt that between certain metals there may exist chemical combinations as between gold and lead or zinc or tin ;and in the cases of some of the amal- gams ihe existence of chemical combiiiations is indicated 1.By the fact that a large amount of heat is set free when they are alloyed with one another. 2. By the fact that the alloys do not possess the typical pro- perties of the groups to which they belong. At present so little is known with regard to the chemical as well as the physical behaviour of these alloys that until they have been better studied it is unnecessary to enter more fully into the subject. Before concluding I cannot but thank Mr. Bassett for his valuable assistance in carrying out and arranging the above detailed experiments especially those with the differential air- thermometer as well as t.hose with the method for showing conduction for heat; to him is due as much as to myself any credit in employing the modifications described as we worked them out and arranged them conjointly.* See Reports on the Chemical Nature of Ailoys and of Cast-iron (Brit. ASBOC. Rep. 1863 and 1866).

ISSN:0368-1769    

DOI:10.1039/JS8672000201

出版商:RSC    

年代:1867

数据来源: RSC

摘要:

221 XX.-”Tote 0% some Varieties of Orcltella Weed md product8 obtained from them. By JORNSTENHOUSE, LL-D. F.R.S. &c. IN 1848* I examined two varieties of Rochella tinetoria one obtained from the Cape of Good Hope and the other as 1 was then informed &.om the neighbourhood both of Lima and of Valparaiso. Both of these lichens were much larger &an the Rochella tinetoria produced by the Cape de Verd Islands. ‘’ The South American lichen was from six to eight inches long and its stems in some instances as thick as those of a goose puiU.” Both of these lichens were pronounced by the eminent botanist Dr. Scouler of Glasgow to be large varieties of the Kochella tinctoria. I have recently submitted specimens of these lichen8 to Mr. Bennet of the Botanical Department of the British Museum and his assktant Mr.Carruthers by whom Dr. Scouler’s opinion was confirmed. On showhg the South American variety to Messrs. Benjamin Smith and Son the oldest and most extensive manufacturers of archil in London they at once recognized it as RoclZeZlu tinetoria from Chili known in commerce as Valparaiso weed which is but rarely imported into this co.untry; while the so-called Lima weed which is largely imported is Bochella fuciformis like that of Angola Zanzibar Madagascar &c. The colour-yielding principles which I extracted from the Valparaiso and Cape of Good Hope weeds I described under the name of a and orsellic acids. From the results of my analyses and from their reactions which agreed precisely with those of iecanoric acid Gerhardt inferred that both my a and /3 orsellic acids were identical with the lecanoric acid of Schunck and consequently that the acid produced by acting on them with baryta or lime was orsellinic acid.I have since made experi- ments which convince me that Gerhardt’s conjectures are perfectly correct. In the Ann. Ch. Pharm cxsxix 22 Hesse gives the analysis of Rochella tinctoriu (De Cand.) from the Cape de Verd Islands which as might be expected he finds to yield lecanoric acid; and also of the RociieZla fuciformis (Achar.) from * Phil. Tram 1848,p. 63. Ann. Ch. Pharm Ixviii 65. VOL xx. R 223 STENHOUSE ON SOXE VARlETzES OF OROHELLA WEED Aagola Zanzibar Madagascar Ceylon and Lima,all of which he Ws yield erythrin (erythric acid).What is now known in amerce as Lima weed is Rochella fuciformis and therefore eatirely different fiom the archil weed (Rochella tinctoria) analysed by me in 1848 which I then described as &om the iL neighbourhood both of Lima and Valparaiso." This explaina the apparent discrepancy between my results and those of M. Hesse his Lima weed being Bochetla fucifbrmis whilst mine was the Rochella tinctoria now known in commerce as Valparaiso weed. It is very difFicult to aacertain the exact locality &om which theae lichens are obtained as importers for obvious commercial reasons are very averse to give information on the subject. On the Preparation of Urcin and Eiythrite. For the extraction of erythrin from Rochella fiicifomis I followed the process first described by me in 1848 with the following slight modifications 2-3 lbs.of the lichen are macerated for 20 minutes with a milk of lime made by slaking Q lb. of lime in 3 gallons of water and the partially exhausted weed is then treated with a fresh quantity of milk 'of lime. A third maceration is found completely to exhaust the lichen. These weak lime-liquors are employed instead of milk of lime in ex- tracting fieah quantities of weed whilst the first and strongest liquor is filtered as rapidly as possible through bag filterrJ about 6 inches wide and 6 feet long which will be found the most convenient for this purpose; and the clear liquor as it comea through is immediately precipitated by hydrochloric acid a8 protracted contact with the lime decomposes a portion of the erythrin.The precipitated erythrin is collected in bag filters and when the greater portion of the mother-liquors have thus been removed it is freed from adhering hydrochloric acid and chloride of calcium by being washed once or twice. This is best accompliahed by stirring up the erythrin with a consider-able quantity of water and again collecting it. To transform the erythrin thus obtained into orcin and erythrite it is again dissolved in a slight excess of milk of lime and boiled for half an hoiir in a vessel furnishedwith a long condensing tube so as to exclude the air which as observed by De Luynes prevents in a great measure the formation of a deep red-coloured AND PRODUCTS OBTAINED FROM THEM.resinous matter. The aoxution now containing orcin and erythrite is filtered the exceas of lime removed by passing a stream of carbonic acid gas through it (or more conveniently on a large scale by exactly neutralizing with dilute sulphuh acid) and evaporated nearly to dryness first over a sand-bath and finally over a water-bath. As orcin is tolerably soluble in benzol whilst erythrite and the dark-brown colouring matter are insoluble in that menstruum their separation is best effected by treating the mixture above described with benzol boiling between 11O0-l5O0 (toluol &c.) in a flmk of tin or any other metal connectedwith a condenser and heated in a para& bath. As the distillation proceeds the water contained in the mixture of orcin and erythrite distils over with a portion of the benzol.After 20-30 minutes’ digwtion the flask is disconnected from the condensing apparatus and the nearly colourless solution of orcin in benzol is poured out of it and agitated in a glass flask with about one-tenth of its bulk of water. This extracts the orcin from the benzol which after separation may now be poured back into the tin flask and the digestion continued as before. After this operation has been repeated three or four times the solid matter in the tin vessel is extracted by boiling water filtered when cold to separate resinous matters and other impurities and evaporated nearly to dryness. After standing several days a large quantity of erythrite crystallises out.Thismay be purified by washing with cold spirit pressing and recrystallising once or twice from hot water. The aqueous solutions of orcin obtained by the above method on cooling usually deposit a quantity of nearly colourless crystals and the whole of the orcin is readily obtained by sufficient concentra- tion. When it is wished to obtain colourless orcin we have only to purify by a second treatment with benzol and recrystal- lisation from water. The advantage of the above described method consists in enabling us not only easily to separate orcin and erythrite but also to obtain pure orcin with compara-tive facility &om mixtures contaminated with large quantities of colouring matter. Action of Chloridk of Sulphur on Or&.When orcin in fine powder irJ added to subchloride of sulphure hydrochloric acid ia evolved and a large quantity of a sulphur-R2 %!?4 S!lTNHOt7SE ON SOME VARIETIES OF OBCHELLA WEED ydhw compound ia produced wliich is amorphous andinsoluble zn water alcohol ether benzol bisulphide of carbon and chloro- form It is solublein caustic alkalis with partial decomposition md when strongly heated it ia decomposed but does not fiNlbJ;ime. Orsellinic Ether. The pas9 erythrin as extracted from tbe “orchella weed,” affer being dried at a very gentle heat is digested for five hours with eight times its weight of alcohol (anhydrous is the best) the greater portion of the alcohol distilled 06and the residue evaporated nearly ‘to dryness on a water-bath.The viscous substance thus obtained is boiled with 10 parts of water allowed to cool collected pressed and dried at looo. This mixture of orsellink ether picroerythrin and resinous matter is boiled with 20 times its weight of benzol for half an hour and by this means the ethylic orsellinate being very soluble in hot; benzol is perfectly separated from the picroerythrin and other impurities which are quite insoluble in that menstruum. On distilling off the benzol the ether is obtained in comparatively large crystals which after one or two crystallisations from hot water are perfectly pure. This method has great advantages over the ordinary one of repeated crystalliaations from water as the crude ether contains a resinous substance which greatly.impedes filtration ; and picroerythrin being soluble in water can only be separated from the ether by this means with great difficulty. In fact I have found that orsellinic ether prepared by the old method after three crystallisations &om water leaves a residue of picroerythrin on being dissolved in benzol. This will account for my statement in the Froceedine of the Royal Society xii 263 that orsellinic ether on being boiled with lime yields small quantities of erythrite. Diiodorsellinate of Ethy1. Thig substitution-compound is obtained by acting on ethylid orsellinate with chloride of iodine. For this purpose a cold aaturated aqueous solation ef the ether if3 precipitated by a dilute solution of chloride of iodine containing excess of iodine.Great care must be taken to use a very dilute solution of chloride of iodine and not to prec.ipitate thewhole of the ether AND PRODUCTS OBTAINED FROM THEM. The white precipitate is collected washed wellwith cold water. in which it is almost insoluble dried and disBolved in ah& 10 times its weight of hot bisulphide of carbon. After filtration to separate impurities a portion of the bisulphide is removed%y distillation and the solution allowed to cool. The crystals of ethylic diiodorsellinate thus obtained are purified by several recrystallisations first out of bisulphide of carbon and fhally out of spirit. It crystallises from its solukions in small needles. It is moderately soluble in benzol bisdphide of carbon and boiling alcohol; much less so in cold spirit and but very slightly soluble in boiling water from which it separates in the crystal- line state on cooling.It can be heated to 100" without decom- position; at a higher temperature it melts and on increasing the heat decomposes giving off vapours of iodine. Its alcoholic solution decomposes after Borne time. The following are the results of its analysie :-I. 0320grrn. gave 0333grm. AgI. 11. *314grm.gave *328grm. AgI. III. *331grm. gave 0325grm CO, and *072 grm. H,O. Fer cent I 11. III C, I?; 120 26*74 --26-79 H, = 10 293 -2.41 I = 254 56.69 56.23 56.45 - 14.29 --0 = 64 44.8 100*00 The formula is C1,H,,I,04 = C8H512(C2H5)04 Orsellinate of Methyl. This waa prepared by the same process as the ethyl corn-pound,,substituting methylic for ethylic alcohol.Diiodorsellinate of Methyl. Tb compoupl was prepared and purified in the Bame manner as the corresponding ethyl-compound. Like that Rubstance it crystallises in needles and is soluble in benzol bisulphide of carbon spirit and boiling water. It is not decomposed at loo" but at a higher temperature melta and gives off iodine. 226 STENHOUSE OX SOME VARIETIES OF 0RCHF';T;LA WEED. The iodine determination corresponds to the formula C9H,I,O = C,H,I,(CH,),O,. 4833 grm. gave *381grm. AgI. €& = 108 24.89 Per cent. -I. H,= 8 1'84 -y. 0,= 64 14.75I = 254 58.52 I 58.32 434 100*00 Mode of Estimating the amount of Coloupyielding Matter in Lichens. Ln my fiat paper on lichens in the Philosophical Tranaactions for 1848,already referred to I gave two methods for determining the amount of colour-yielding principles in lichens.One of these consisted in exhausting the lichen with milk of lime precipi- tating with acetic acid collecting the precipitate on a weighed filter drying it at the oydinary temperature and then weighing it. In this way the amount of colouring principle was directly determined. The only objection to this method is that it is tedious and difficult for any but a chemist to perform. The other consisted 61the employment of a standard solution of hypo-chIorite of calcium For this purpose ''any convenient quantity of the lichen say 100 grains is eut into very small pieces and then macerated with milk of lime till all the colouring piillciple is extracted.Three or four macerations are quite sufficient for this purpose if the lichen has been suflciently comminuted. The clear liquors should be filtered and mixed together. A solution of bleaching powder of known strength should be added to the lime-solution from a graduated alkalimeter. The moment the bleaching liquor comes in contact with the lime- solution of the lichen a blood-red colour is produced which disappears in a minute or two and the liquid has only a deep- yellow colour. A new quantity of the bleaching liquid should then be poured into the lime-solution and the mixture carefully stirred. The operation should be repeated as long a8 the addition of the hypochlorite of calcium causes the production of the red colour for this ghows that the lime-solution still contains unoxidizedcolouringpiinciple.Towarch the end of the pro- CHAPMAN ON LIMI!CED OXJBATION ETC. cess the bleaching solution should be added by only a few drops at a time the mixture being carefully stirred between each addition. We have only to note how many measures of the bleaching liquor have been required to destroy the colourhg matter in the solution to determine the amount ‘of the coloUring principle it contained.” Improved PTocess.-100 grains of the lichen are macerated with a dilute solution of caustic soda two treatments being sufEicient to extract the whole of the colouring matter. The amount of colour-yielding principle in this solution is then determined as in the above process employing a solution of hypochlorite of sodium instead of the corresponding calcium-salt The great advantage is that the liquor remains perfectly transparent no turbidity being produced aa in the preceding procesa by precipi-tation of carbonate of calcium

ISSN:0368-1769    

DOI:10.1039/JS8672000221

出版商:RSC    

年代:1867

数据来源: RSC