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CHEMICAL News,
February 28, 1879:7
The Liquefaction of Gases.

87 answered the question by experiment. Two receivers

were taken; one was filled with air compressed to about THE CHEMICAL NEWS.

20 atmospheres; the other receiver was exhausted by an

air-pump. The two receivers having been connected by VOL. XXXIX. No, 1005.

a short pipe in which there was a stopcock, the entire apparatus was immersed in a cànful of water. Then by opening the stopcock the compressed air was permitted

to flow from the full to the empty receiver. ON THE LIQUEFACTION OF GASES.* The advocates of the old theory of heat would have By J. J. COLEMAN, F.I.C., F.C.S.

said that since the compressed air in this operation dilated to twice its original volume heat must disappear to meet

the increased capacity of air in cunsequence of its expanThree methods have been employed in the liquefaction of sion. But the result, indeed, entirely contradicted this. gases :—I. Increase of pressure at normal temperatures. There was no cooling effect whatever measurable by the II. Abstraction of heat at normal pressures. "III. The most delicate thermometer, a result which certainly would combination of these two operations. The gases which have occurred had the compressed air been made to discan be liquefied by pressure at normal temperatures are place the atmosphere. In fact it has since been abunlimited. Natterer showed us, some years ago, that under dantly proved that the reduction of temperature which a such conditions the enormous pressure of 3000 atmospheres compressed gas undergoes when allowed to expand into was insufficient to liquefy hydrogen and oxygen. It was the atmosphere is owing to work done in displacing the reserved for our countryman, Dr. Andrews, to demonstate atmosphere, which offers the well-known resistance of about the fallacy of relying upon pressure alone for gaseous lique- | 15 lbs. per sq. inch to the escape of the gas. faction. To use the words of Prof. Wurtz in his recent Fara- Putting the facts into a brief statement, it may be taken day Ledure, he has shown us that with all vapours there is a as proved that when a compressed air or gas is allowed to point at which the molecular movements caused by heat expand the greater the resistance, and consequently the finally gain the victory over the force of cohesion, whatever work done in overcoming such resistance, the greater the be the pressure to which the air is subjected. Dr. Andrews resultant cooling effect produced. Expand a compressed describes it as the “ critical point;" Mendelejeff names it gas into a vacuum, no cold is produced; expand it in the "absolute boiling-point.”

opposing the atmosphere, some cold is produced ; expand It is, therefore, easy to understand why Natterer failed it against a resistance such as that of a heavily loaded and Cailletet and Pictet succeeded with their experiments. piston so as to contribute to its motion, and the maximum Indeed, it would appear from these researches, and the cooling effect is produced. Sir W. Thomson, Rankine, principles underlying them, and if it be taken for granted and Clausius have worked out the whole subject mathethat the molecules of all gases have a tendency to gravi- matically, but it may be convenient to quote Clausius. tate to each other independent of external pressure, that He takes typical cases to illustrate the difference on the of the two agents for effecting the liquefaction of gases one hand of the expansion of a compressed gas as against the abstraction of heat is more efficacious than the appli. the resistance of the atmosphere; on the other hand, as cation of pressure.

against the resistance of a loaded piston. Assuming an This is evident, and follows from the ordinary laws of initial pressure of 5 atmospheres in each case, he shows gaseous expansion. It is a well-established fact that that to bring the temperature of the expanded gas to the gases expand uniformly, and that the rate of expansion is initial temperature before expansion, the first case would such that a given voluine of gas at the freezing-point of require 17 units of heat as against 74:9 required in the water will become double its bulk at 491° F. Therefore, second case. if it be followed in its path of contraction for temperatures Long before the inechanical theory of heat was enunbelow freezing-point, by the time its temperature becomes ciated Dr. Gorrie utilised for freezing-machines the intense reduced 491°, which is the absolute zero of physicists, the cold produced by expanding, a gas behind a working gas must necessarily be either liquefied or solidified. piston. Though his theoretical ideas were somewhat The greatest artificial cold yet produced has not ex- conlused, Charles Randolph noticed and commented upon ceeded about 220° below zero F.; but it would be rash to it in the case of the compressed air-engine erected at assume that it is impossible to produce greater cold. Govan Colliery in 1849. Air compressed to 20 to 30 lbs. Indeed, it is not improbable that means may yet be found to the square inch was sent down a shaft 176 yards deep, to produce cold sufficient to liquefy either oxygen or hy- and along a road about 700 yards long, where it was used drogen at ordinary pressures. The question at once for working an old steam-engine in the place of steam, arises, what has already been done in the production of the result being that the ports of the engine cylinder were extremely low temperatures, and in what direction can frequently blocked up with ice. such efforts be extended. But practice is dependent upon The same phenomena can be observed in any kind of principles, and for principles we must fall back upon the machinery worked with compressed air. In fact I have mechanical theory of heat, thoroughly established and frequently observed the temperature of air issuing from accepted universally by physicists, but as yet imperfectly the cylinder of coal- and rock-cutting machines to register understood by numbers of chemists educated in the old fully many degrees below zero. Indeed, by such a process school of Black and Leslie.

an unlimited reduction of temperature can be produced, It is useful in the outset to recal certain experiments of provided the air or gas be subjected to sufficient compresDr. Joule ; and, parenthetically, it may be observed that it sion before expansion, and supposing always that care be is to be regretted that no collected edition of the papers of taken to remove the heat of compression by passing the this able man has yet been published. In his paper read compressed air through a surface condenser, kept cool to the Royal Society in June, 1844, some very interesting with water, or by the actual injection of water at the experiments with compressed air are detailed. The paper time of its being compressed. When I first turned atten. commences by reference to the well-known fact that com- tion to the subject i exercised myself considerably in pressed air when expanded becomes cooled, that is, when efforts to contrive a method of expanding air or gas so as it escapes into the atmosphere; but Dr. Joule asked him- to cause it to do the maximum of work in the act of exself this question-"Would the cooling effect be greater pansion. But I speedily became convinced of the unor less were the same air expanded into a vacuum ?" He likelihood of anyone being able to invent a more perfect

instrument for converting the expansion of an elastic fluid A paper read to the Chemical Section of the Philosophical Society into work than is afforded by a well constructed steamdrawings of the machinery will be found in the Transactions of the engine. Mallard shows us that compressed air made to latter body, published in Glasgow.

do work in an engine, at an initial pressure of 10 atmo

water.

88
The Liquefaction of Gases.

CHEMICAL NEWS,

February 28, 1879. spheres and temperature of 62°, should become reduced to , Between these two motive cylinders is a heavy Ally-wheel

- 193° F. on being discharged, putting aside deductions of about 7 tons weight. It became very evident in the for friction, &c. This illustrates the limitless production early stages of construction that some kind of automatic of cold by such a process; for let the initial pressure be regulator would be required, so that the speed of the higher, say 20 or 30 atmospheres, and the cooling effect machine should ne such as to exercise no undue suction will correspondingly be produced. Indeed, it seems to me upon the shale retorts, otherwise atmospheric air might that if Messrs. Pictet and Cailletet had in their experi- have been taken into the machine in admixture with the ments made the compressed oxygen or hydrogen do more hydrocarbon gases. This was accomplished by putting a work in expanding than the mere displacement of the small gasometer governor between the two motive cylın. atmosphere, then they would have been liquefied at much ders just described, and adjusted so delicately that a varialower pressures. M. Pietet employed no less than 9000 lbs. tion of pressure equivalent to o 25 would, by a system of pressure per square inch in his experiments. But it can levers, actuate a throttle-valve and open or close the be shown that a compression of only one-tenth of this, admission of steam to the cylinder, and thus regulate the or goo lbs. per square inch, raises a gas to 1200° F.; and speed of the engine. These levers, when once adjusted, that if gas so compressed be brought down to 60°, and cause the engine to run at full speed of 80 revolutions then expanded in the act of doing work, it must neces- when the pressure in the retorts rose to 0'75 (or f) inch, and sarily be cooled down to a lower degree than any yet ex- to run at half speed when the pressure sank to 0-25 inch. perimentally shown, and which would probably be We will now irace the progress of the hydrocarbon gases. sufficient to effect the liquefaction of any gas we are They are sucked into two pumps worked by the motive acquainted with.

cylinders A and A1, the piston rods of which extend to the Again, in their experiments there must have been a pro- two pumps, and are therein compressed to about 8 aimo. duction of heat militating against the liquefaction from spheres absolute, or a little more than 100lbs. per square inch the friction of the gases in escaping into the atmosphere above the ordinary atmosphere. Under these circumstances through a minute orifice.

some hundreds of degrees of heat are generated which This is the theoretical aspect of the case, but in practice require to be removed this is accomplished in great part several considerations arise.

by injeđing about 8 cubic inches of water into each pump It is very difficult constructing the necessary appa: every stroke of the engine. This water is forced into the ratus strong enough without having such a mass of gas.pump by small injection-pumps. The compressed metals as to communicate heat rapidly to its contents; gas is now conveyed by the pipes with injected water to and, further, the friction of the piston rings and the rubbing the top of a surface condenser, and passes downwards surfaces of the valves, piston-rods, &c., is difficult to through 200 iron tubes of about 1 inch diameter and 4 feet neutralise, lubrication at excessively low temperatures 6 inches long, these tubes being surrounded with cold being troublesome.

The mixture of compressed gas, liquefied hydroHow far these difficulties may be overcome on original carbons, and injected water arrives at length at about research remains to be proved ; but they have been dealt 70° F. in reservoir at bottom of the surface condenser. with to some extent in machinery constructed under my. The water and liquefied hydrocarbons are allowed to direction for technical purposes, and it may be observed escape by an automatic regulated cock, and the comthat this machinery differs essentially from apparatus pre pressed air is carried to the top of a second surface conviously used, inasmuch as its construction admits of the denser, precisely similar in construction and with precisely liquefied gases being produced in a continuous stream, similar outlets at the bottom reservoirs. It is then carried whereas in all former experiments with the liquefaction of forward to the top of the third surface condenser, where it gases, a small volume has been first confined and lique first passes downwards through a chamber packed with fied, the experiment then coming to an abrupt end. salt, so as to convert any suspended mixture into brine,

In a paper read to the Chemical Society of London and afterwards further downwards through 200 more (Sept., 1875) I described the effect of pressure and cold 1-inch iron pipes in the case not surrounded with water. upon the gaseous products of the distillation of carbona. The compressed gas-still of about 8 atmospheres pressure ceous shales, which remain permanent after all the con- is finally used for working the motive cylinder, which does densable vapours within are removed in the usual way by not differ in construction fiom a steam cylinder, from which cooling to atmospheric temperature. These gases, whilst it is discharged after doing work considerably below zero being permanent at 50°, yield under the influence of a Fahr. This constant stream of ejected and cold gas is pressure of about 10 atmospheres and a cold of 200°, large made to circulate around the condensing pipes of the quantities of volatile liquid hydrocarbons, consisting third surface condenser, and is finally carried away to be chiefly of butylen, amylen, hydride of amyl, and hexylen. burnt as fuel under the boiler, being chiefly a residue of

The machine which is the subject of this paper was marsh-gas and hydrogen. designed to deal with 300,000 cubic feet per day of this The cycle is thus complete, and it only becomes neces. waste gas, by subjeđing it to the cold and pressure just sary to indicate all the cylinders and note the volumes and mentioned, and has now been working three years, temperatures of the incoming wtaer and gas and their final having liquefied, in round numbers, about a quarter of a temperatures to have most interesting proof of some of million gallons of these liquid hydrocarbons. It involves the most important fundamental laws of thermo-dynamics. (1.) The pumping of the gas by steam-power into a

The machine was driven by steam of 50 lbs. initial pressystem of tubes capable of being externally sure, and when it became desirable to indicate the cylincooled, and from which condensed liquids can be ders the working pressure was kept as nearly as possible drawn off by ball-cocks.

100 lbs. to the square inch, and the piston speed moderate, (2.) Employing the compressed gas after being deprived circumstances

it was found that the

viz., 144 feet per minute (48 revolutions). Under these of its liquid for working a second engine coupled with and parallel to the first, thus receiving a por- Motive cylinder A indicated

33 h.p. tion of the force originally employed in the com

Ar

7 pression. (3.) Employing the expanded gas after having had its

Total driving power..

40
temperature reduced in the act of doing the work The gas-pumps offered a resistance ofi:

32
of pumping for supplying the necessary cold for
cooling a portion of the condenser pipes to zero.

Difference ..

8 The machinery is kept in motion by the piston's cylin- The indicator cards show that the volume of ders, A and A 1, the pistons of which are connected with compressed gas introduced into cylinder A 1 became rea common crankshaft, both being of 30-inch stroke. | duced to atmospheric pressure by the end of the stroke.

19

WICAL NITO;} Improved Method for Making Platinum-Alloy Assays. February, 29, 1879.

89 It is admitted to the cylinder not at the full pressure of, but there is no doubt even lower temperatures would have 100 lbs., but by means of a reducing valve at about 60 lbs., resulted if the capabilities of the machine had been being thus cut off at one fourth of the stroke. The re- stretched to their utmost limit. covered power seems comparatively small, but it must be The hydrocarbon liquids obtained by this process are taken into account that there is some loss of gas during those produced by pressure alone escaping from the first its progress through the machine at the points where the and second, and those escaping from the third surface conliquid hydrocarbone are drawn off (probably 10 per cent); denser at temperatures approaching zero, the result of also, that there will be some of the gas liquefied, and that combined cold and pressure. The former has generally a the residue of hydrogen and marsh-gas, being so very specific gravity of 0-710 at 60°, the latter of about 0.670 mobile, might have a tendency to pass between the at 60°. The total produce of condensed hydrocarbons has piston block rings and the inside face of the cylinders. been about 2000 gallons per week, which, when distilled, Taking these fačts into consideration, the working of this yield a considerable percentage of extremely volatile liquid cylinder has been very remarkable. It is generally coated hydrocarbons of specific gravities varying from 640° to externally with some inches thick of ice from the freezing 0-660. These liquids, judging from the action of bromine, mixture deposited upon it from the external atmosphere. are chiefly amylen, hexylene, and dissolved butylen, with

The indicator cards of the gas-pump are very beautiful, a small admixture of the corresponding hydrides, whereas and show a very near approach to the true isothermal the extremely light portion of American petroleum are in curve of compression, resulting from the law of Mariotte. | main composed of the hydrides of the alcohol radicles. No doubt much of the beauty of this card is owing to the The machinery I have just described was built for extremely small clearance spaces at the end of the stroke Young's Paraffin Light and Mineral Oil Co., for dealing of the pump piston, viz., 0-25 of an inch, which again gets with a portion of the gas produced at their works, probably filled up with water from the injecting pumps. Such good about one-fifth. There are some who believe that the curves also demonstrate the efficiency of the injection of ends attained by this machine are as well accomplished the cold water by the small force-pumps, and the super. | by processes dependent upon gaseous absorption, the fluity of elaborate arrangements, for throwing in pulverised absorbent liquids being oils of heavy specific gravity; but water-insisted upon by Colladen, of Geneva, and other my object in this paper is not to discuss this question, but Continental engineers. This machinery has been fre- to call attention to the process as the first application of quently run at pressures approaching 150 lbs. to the square Faraday's principle of the liquefaction of gases combined inch, and piston speed of 240 feet, without ever causing with an application of the principles of the mechanical the pump-barrels or valves to reach a temperature of above production of cold, first foreshadowed by Count Rumford blood-heat.

and Sir Humphry Davy, and developed by Joule, Clausius, The pump-valves are somewhat peculiar in construction, Rankine, and Sir W. Thomson. the arrangement being suggested by my friend, Mr. John Thompson, of Messrs. R. Laidlaw and Sons, the builders of the machine. Each pump end has four suction-valves of 14 ins. diameter, and three delivery-valves of It ins. IMPROVED METHOD FOR MAKING PLATINUMdiameter. Each of these valves work in a wrought-iron

ALLOY ASSAYS. barrel, which contains the spring and the valve-spindle suitably guided. These wrought-iron barrels containing

By NELSON W. PERRY, E.M. the valves are about 24 ins. diameter, and are externally grooved with a thread, so as to enable them to be screwed About a year ago I had occasion to make some assays of into the ends of the pump, or with the whole contents re- platinum alloys. The first method employed consisted of moved at pleasure.

cupellation with addition of Ag and Pb, the loss being The valves have worked very well, but the springs being base metal. The silver was obtained by precipitating light require replacing at frequent intervals. Subsequent from solution in HNO3 with HCl. This necessitated experience has certainly induced me to prefer valves lewer bringing the precipitate on a filter, washing thoroughly in number, and of larger diameter so as to admit of stronger (giving a large filtrate for evaporation), drying, weighing, springs, but on the whole the arrangement has been very and calculating the Ag from weight of Agci obtained. effective.

I will not detail this method further, but mention this last The piston blocks of the gas-pumps were originally pro- step to show one of the tedious steps in the operation. vided with three-eighth square steel rings, but latterly it Doubtless many of your readers are familiar with this has been found that the common f-inch square cast-iron assay. The results by this method--strange to say, an ring wears best, and keeps the pumps in good working established one-I found exceedingly unsatisfactory and order for fully six months.

inaccurate ; one of the causes of its inaccuracy being The machine has been working continuously from Mon- that the percentage of platinum is obtained by difference, day mornings to the following Saturday night as a rule namely, all the other constituents being determined, their without stopping, and has not been stopped for over combined percentage is subtracted from 100. The error hauling or repairs more frequently than the average of | is therefore cumulative for platinum. The assay, or rather steam-engine machinery

combined assay and analysis, as it is, required almost as Passing from mechanical details, as an example of results much time as a good quantitative analysis, and yet could obtained by the machinery the following summary of con- lay no claim to equal accuracy. secutive observations made over a period of thirty days at I therefore set myself to work to devise, if possible, the latter end of 1876 may be stated :

some better method, the results of which I set before you.

In platinum alloys, or native platinum, the metals to be Average temperature of the gas after

determined are base metal, Ag, Au, Pt, and iridosmine. being expanded and discharged from 30° below zero F.

Base metal is removed from the others by cupellation. the motive cylinder A i

Silver is soluble in H2SO4, while the others are un. Average temperature of the com

touched. pressed gas on its way to be expanded -20° above zero F.

Platinum when alloyed with twelve times its weight of after leaving the surface condenser S3)

silver, is soluble in HNO3. Minimum temperature attained by

Gold is soluble in aqua regia, and iridosmine untouched the gas discharged from the motor 47° below zero F. cylinder H I

Making use of the above properties, I was enabled to Practical considerations as to wear and tear, steam con- effect a separation of the metals both accurately and sumption, &c., made it undesirable at that time to increase rapidly, no filtering being required, and all the washing the working pressure above 135 lbs. to the square inch,' being done by decantation.

by acids.

Colouring Matters Derived from Diazo Compounds. 90

{ February 28, 1879

, Assay of platinum alloys containing base metal, silver, Prerident-Warren de la Rue, F.R.S. platinum, gold, and iridosmine.

Vice-Presidents—The list remains unaltered with the Charge Pt alloy 200 Mg, pure Ag 150 Mg, or sufficient insertion of J. H. Gladstone and omission of Warren de to produce perfect cupellation (exact weight.)

la Rue. Wrap charge in sheet lead and cupel. Weigh button. Treasurer-W. J. Russell. Loss = base metal.

Secretaries—W. H. Perkin, H. E. Armstrong. Flatten button, anneal, roll out thin, anneal again, and Foreign Secretary-Hugo Müiler. make into cornet as in gold bullion assay. Introduce Other Members of the CouncilM. Carteighe, A. H. cornet into parting flask and part with concentrated Church, W. N. Hartley, C. W. Heaton, E. Riley, W. H2SO4. Wash, anneal, and weigh. Loss from previous Chandler Roberts, T. &. Thorpe, W. Thorp, J: L. W. weight=Ag in original alloy + Ag added for cupellation. Thudichum, W. A. Tilden, R. V. Tuson, R. Warington.

Alloy cornet with at least twelve times the amount of The following gentlemen were elected auditors for the Ag that there is Pt present, and, as before, form cornet year :-R. J. Friswell

, J. Spiller, and J. M. Thomson. and part first with HNO3 sp. gr. I'16, and then HNO3 sp. The President then called on Dr. Otto N. Witt to gr. 1.26. Wash thoroughly, anneal in annealing cup, and read a paper On Colouring Matters Derived from Diweigh. Loss=Pt.

azo-compounds.During the last three or four years Treat residue with aqua regia, obtain Au by loss—the aniline colours have come into such general use as to, in residue is irridosmine.

many instances, replace the old costly artificial and Time to complete assay in duplicate, 2 hours 45 minutes. natural dyes. Although there has been known for some

The quality of Ag added should at least be sufficient, time a great variety of magenta, violet, and blue aniline dyes, so that after the addition the Ag in the alloy will be to the green and yellow dyes were almost unknown until quite Au as 3:1.

recently. Three years ago the author, in a paper read As platinum and irridosmine add greatly to the insusi- before the Society, indicated a theory as to the relation bility of the compound, silver in sufficient quantity must between the chemical constitution and the colouring be added to prevent" freezing" and give a perfect cupella- power of aromatic substances. In this paper he pointed tion. Any large excess over these requirements is to be out that there existed a series of compounds, the colour avoided-first, because the residue, after parting, will in of which was in close relation to their chemical constituthat case be non-adherent and in a more or less fine state tion. The first link of this series is azo-benzene, of subdivision, which may occasion loss in washing by C6H5-N=N-C6H5. This substance is of a deep yellow decantation ; second, the larger the button cupelled the colour, but being devoid of salt forming groups is not more difficult it is to obtain a good cupellation, and the applicable for dyeing. By introducing amido: or oxy. greater the loss of Ag during the process. It may, for this groups, compounds can be formed having strong affinities reason, sometimes be necessary to use only 100 Mg of the for textile fibres, which increase with the addition of each alloy for assay instead of 200 Mg, as above.

salt-forming group into the molecule. At the time this The cupellation should take place at a moderate tem- paper was read amido-azo-benzene and tri-amido-azo. perature, until near the “ blick," when the assay should benzene were the only dyes of this class known; the first be thrust back into the hottest part of the furnace to pre- was of a beautiful bright yellow colour, but fugitive; the vent "freezing.” The button must remain in the muffle second was fast, but dull. Since that time the interuntil all the Pb is gone.

mediate di-amido-azo-benzene has been formed and In parting with H2SO4, boil for several minutes. In named chrysoidin, which combines the beauty of the other respects, this operation is identical with the gold-monamido- and the fastness of the tri-amido-bodies. bullion assay. Any large excess of Ag over twelve times The preparation of chrysoidin is then given. Griess has the amount of Pt in alloy is to be avoided, as it causes the shown that not only can amido-azo-compounds be obresidue, after parting, to be too fine and float, thereby tained, but that the oxy-derivatives of azo-benzene and occasioning loss in washing. Insufficient Ag is even other similar bodies can be prepared by the action of di. worse, as the Pt will then be only incompletely dissolved. azo-compounds on the corresponding phenols; these oxy

By the above method I was successful in obtaining very derivatives are also dyes; so that these di-azo-compounds closely duplicating results, was enabled to do away with have opened out an almost inexhaustible mine of new all precipitation and filtering, no apparatus being required, and beautiful dyes. Since Hofmann's paper on chrysoidin except that necessary for the gold and silver bullion assay, investigations on this class of compounds have been set and, what is only second in importance to accuracy, attained on foot in the laboratories of almost all aniline colour results with the least expenditure of time. Mr. William manufacturers. The patents taken out for their production Strieby, A.M., E.M., has assisted me materially in perfect. are constantly increasing in number. In consequence of ing this assay, and employed it in his own work with his connection with Messrs. Williams, Thomas, and equally satisfactory results.

Dower the author has not been able to carry out his I present the above to your readers, hoping it may prove original intention of describing fully the preparation and of service to some engaged in similar work.-Engineering properties of all his new azo-colours. The prototype of and Mining Journal.

these compounds is chrysoidin. The author has already given a description of the properties of this substance in Fourn. Chem. Soc., ii., 457, 1877: He has since prepared

in a pure state the following analogous substances closely PROCEEDINGS OF SOCIETIES.

resembling the typical product :-Ortho-tolyl-phenylenchrysoidin, para-tolyl-phenylen-chrysoidin, phenyl-toluylen-chrysoidin, ortho-toluylen-chrysoidin, para-tolyl-toluy

len-chrysoidin, phenyl-toluylen-chrysoidin sulphonic acid, CHEMICAL SOCIETY.

a-naphthyl-phenylen-chrysoidin sulphonic acid, a-naph. Thursday, Februarv 20, 1879.

thyl-toluylen-chrysoidin sulphonic acid. Each basic

colour has an acid counterpart similar in shade and con. Dr. J. H.(GLADSTONE, F.R.S., President, in the Chair.

stitution but containing hydroxyl- in place of amido-groups. The acid counterpart of chrysoidin has been prepared by

Baeyer and Fäger, and studied by Typke. This compound AFTER the confirmation of minutes, &c., the following is a beautiful but unstable dye. The author therefore certificates were read for the first time :-W. North, F. | introduced a sulpho-group into its molecule by treating Podmore, W. Y. Gent, W. Radford.

resorcin with para-di-azo-benzene sulphonic acid. The The list of Officers for the ensuing year as proposed by substance has since been described by Griess. Its con. the Council was then read

stitution that meta-di-azo-oxy-benzene sulphonic

CHEMICAL NEW} Action of Substances in the Nascent and Occluded Conditions
February 28, 1879}

91 acid. Its acid sodium salt is sold under the name of some time by SH2, so that it can be used to titrate crude tropæolin O. By a similar reaction monoxy-azo-benzene soda. A still better indicator is the dimethyl-diazo-benzene sulphonic acid has been obtained from phenol. Its sodium sulphonate of ammonium. sali is known as tropaolin Y. Tropæolin 000 No. 1 is Dr. RUSSELL then took the chair during the reading of oxy-a-naphthyl, and tropæolin 000 No. 2 the sodium a paper by Dr. GLADSTONE entitled, “ Investigations into salt of oxy-ß-naphthyl-azo-phenyl sulphonic acid. Tro- the Action of Substances in the Nascent and Occluded Conpæolin 0000 is isomeric with tropæolin 000 Nos. I and ditions (Hydrogen, continued),” by J. H. GLADSTONE 2. Another class of azo-colours can be obtained if the and A. Tribe. From a recent study of the behaviour of salt-forming properties of amido-azo-benzene and analo nascent and occluded hydrogen (Chem. Soc. Fourn., 306, gous compounds be intensified by introducing one or more 1878) the authors concluded that these conditions of the sulpho-groups. Thus, by acting with para-di-azo-benzene element are not, as hitherto supposed, different, but are sulphonic acid on dimethyl-anilin, a dye is obtained, in closely related if not identical, and that the activity of the which, however, the basic properties are too prominent, so-called nascent hydrogen is the consequence of its and to obtain a proper equilibrium one phenyl instead of intimate association with the metals employed to bring two methyl groups must be introduced into the molecule about the liberation of the element. In the present paper of amido.azo-benzene sulphonic acid. Thus is produced the authors have examined the action of nascent and one of the most beautiful of the azo-colouring matters. occluded hydrogen on nitric and sulphuric acids. The It is known as tropæolin 00. The author gives a detailed nascent hydrogen was obtained by electrolytic decomposidescription of the preparation and purification of phenyl- tion of the acids in Hofmann's arrangement for illustrating amido-azo-benzene, which, when pure, forms leaflets or the composition of water electrolytically. Nascent needles of a fine golden yellow colour; M.P. 82° ; soluble Hydrogen and Nitric Acid :-Faraday and Bourgoin have in benzolin, alcohol, ether, and benzene. The author shown that ele&rolytic hydrogen reduces strong nitric reserves for a future communication a description of amido- acid, but only imperfectly or not at all when diluted with diphenyl-amin. Phenyl-amido-azo-benzene when treated an equal bulk or more of water. If the oxidation of the with amylic nitrite and acetic acid yields a nitrosamin | freed hydrogen in this action results from its being in the crystallising in orange needles, melting at 119-5°; its occluded condition, the reduction of the acid would depend formula is C18H14N/0. By the action of di-azo-benzene- on its strength only in so far as this facilitated the desulphonic acid on diphenyl amin, tropæolin 00 is obtained. occlusion of the hydrogenised electrode, and the stronger It is a powerful acid and forms well-defined salts. The acid might be expected to do this the more readily. And author gives a description of the potassium, sodium, amit follows that with a given strength of acid the amount monium, trimethylamin, barium, calcium, and aniline of free gaseous hydrogen should bear some relation to the salts. In conclusion the author trusts that he has suc- rate at which the electrolysis takes place, for were the ceeded in giving a sketch of what may be called the gas freed from its nitric radical, not faster than it could be genuine azo-colours, the true oxy- and amido-derivatives occluded, none should pass through the liquid; but if the of azo-benzene, and analogous compounds. Compounds evolution of the gas were faster than the occlusion, free derived from amido-azo-bodies by the action of amines as hydrogen should escape. The authors have proved that well as coloured substances containing the azo-group, this is the case. Their results are given in the annexed -N=N-, may also be termed azo-colours. The author table – hopes in a future paper to lay before the Society his re

Proportion of searches on these more intricate compounds.

Reduction
Time of

Free
The PRESIDENT said.that all must have appreciated the

Water.
Experiment.

Oxyger.. very lucid and brief manner in which Dr. Witt had

I acid

3105 described this beautiful series of compounds, interesting

68.2 both from a scientific point of view and from their appli.

4
per cent

28.8 cation as dyes.

O water

2994 Mr. Perkin said that the paper was of peculiar interest

215 I acid

30.6 to him, as showing the enormous strides which aniline

to
42

29'0 dyestuffs had taken during the last few years. He would

19

24'2 like to ask whether these dyes were suitable for silk, wool,

I water 8

8

16.8 and cotton ?

I acid
61

17'0 30 Dr. ARMSTRONG remarked that the brief description

4

18

085 65-7 given by Dr. Witt conveyed but a slight notion of the 8

8

0-3 68.7 enormous amount of work concentrated in the results. He would ask Dr. Witt if he could point out the influence Each experiment went on till 35 cc. of oxygen collected of the different groups in modifying colour ? and also if at the anode. In the 2nd, 3rd, and 4th experiments of he had any experience of tropæolin Oo as an indicator in the series i to i the evolution of hydrogen at the cathode alkalimetry?

ceased quite suddenly at the end of three minutes. This Dr. Wirt said that most of the dyes, especially the is due to the presence of nitrous acid, which prevents the sulpho-compounds, were only suitable for silk and wool, escape of hydrogen with eight cells when present in the the amine compounds dyed cotton. He had already proportion of o'059 grm. to 100 cc. of 1 to 1 acid. pointed out two groups concerned in the tinctorial power Occluded Hydrogen and Nitric Acid :—Nothing is known of a substance, which he had called chromogens and as to the action of occluded hydrogen on nitric acid. Dr. chromophors (Chem. Journ. Soc., ii., 403, 1876). Subse Armstrong infers (Chem. Soc. Fourn., 1877, 82) that it has quent results had confirmed these conclusions. Oxy- and no action. The authors charged some finely-divided amido-groups principaliy had to do with the colour of the platinum with hydrogen. On pouring on it some pure nitric dyestuff. The sulpho-group weakened the colour but con- acid the metal became red-hot, the liquid became yellow, ferred stability on it. Also, cæteris paribus, the more oxy- and nitrous fumes escaped; so that occluded as well as or amido-groups contained the more powerful is the dye. nascent hydrogen acts on nitric acid. Palladium charged It does not follow, however, that the beauty of the colour with hydrogen dissolves in nitric acid i to i without increases with its intensity. The heavier the molecule setting free any gas, so that the hydrogen in this case the more the colour tends to the violet end of the spectrum. must be oxidised. Nascent Hydrogen and Sulphuric Some importance must be attached to the localisation of Acid :—The acid was decomposed ele&rolytically. The the salt-forming groups, i.e., the nearer they are together authors conclude that hydrogen associated with platinum in the molecule the more powerful is the colour. Tro- reduces oil of vitriol very readily, sulphurous acid being pæolin 00 has been recommended as an indicator by sometimes formed; a film of sulphur also appears on the Von Müller. It is not affected by CO2, and only after negative electrode. Occluded Hydrogen and Sulphuric

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