CHEMICAL NEWS,

Oct. 15, 1909

Estimation of Carbon Monoxide in Mine Gas.

of course, that it has been prepared with reasonable care, is absolutely stable.

To those who are incredulous about the presence of CO in the atmosphere surrounding industrial centres, it may be interesting to note that Gautier found amounts of C in the atmosphere of Paris varying between o and 9 parts per million. He also analysed samples of laboratory air containing considerably more.

There seems to have been a long period of inactivity after the foregoing publications, the next record of note being that of Kinnecutt and Sanford in 1900 (Fourn. Am. Chem. Soc., 1900, xxii., 14). These authors could not obtain good results by either of the methods of Gautier and Nicloux on account of the impossibility of accurately determining the amount of iodine liberated by directly weighing it, or estimating it colorimetrically. They also stated that the gravimetric method of determining the carbon dioxide liberated during the reaction was unsatisfactory. They asserted, however, that if the iodine be caught in potassium iodide solution and subsequently titrated with thiosulphate of sodium, very close and accurate results could be obtained. Their results are in close agreement with theoretical mixtures subjected to analysis, and showed that the method is capable of determining as little as 0.0025 per cent of carbon monoxide in the air. The authors further stated that they had proved experimentally

193

lengthy paper by himself and Clausmann (Comptes Rendus, 1906, cxlii., 485), and as a result of very carefully conducted and extensive experiments, they came to conclusions which have a very important bearing on our subject, because they not only confirm the accuracy of the 1205 method, but also give specific reasons for the unreliability of gas volumetric determinations of CO in gaseous mixtures. Their conclusions may be summarised as follows: Firstly. In determining CO when present in mixtures to the extent of several cubic centimetres, and after the gas in the ordinary course of analysis had been washed with KOH, bromine water, and pyrogallol, the cuprous chloride solution, even when used in considerable excess, does not absorb all the carbon monoxide.

Secondly.-CO diluted with an inert gas does not burn completely even when exploded in the presence of an excess of oxygen.

Thirdly. The remainder of the CO escaping estimation by either of the above methods can only be determined correctly by passing it through iodine pentoxide at temperatures of not less than 70° C.

These precise statements should make it clear why the absorption method employed by some has seemingly given negative results.

With reference to the combustion method we have never attempted the explosion with excess of oxygen, but have

that other constituents of coal-gas do not influence the accuracy of the method.

In 1903 Fillunger mentioned (Chem. Ztg., 1903, 27) that Moltersky and Nowicky employed a method similar to that just referred to, but they neglected the iodine liberated and only determined the CO2 produced by absorption in Ba(OH)2 solution and subsequent titration. The authors further asserted that hydrocarbons in the mixture had no effect upon the results. They claim an accuracy of o'01 to o'1 per cent of the theoretical.

In 1905, Lévy and Pécoul (Comptes Rendus, 1905, cxl., 98) reverted back to Nicloux's method for the estimation of CO in confined atmospheres, but employed chloroform instead of carbon disulphide for the colorimetric estimation. In a further communication a year later (Comptes Rendus, 1906, cxlii., 162), the same authors confirmed their previous results, and asserted that small amounts of acetylene did not seriously interfere with the accuracy of the method. They found that, while four parts of acetylene per thousand produce a very slight coloration, one part of CO per 10,000 produced an intense colour due to iodine liberated. They therefore came to the conclusion that, in testing normal air for CO, the possible presence of acetylene may be neglected.

In the meantime Gautier seems to have busied himself with the problem of why the volumetric estimation of CO with cuprous chloride gave such unreliable results. In a

we found, after elimination of the ethylene and CO2:102 vol. per cent CO and 0.85 vol. per cent H by passing the mixture through spongy palladium at a temperature of about 300° C. It will be noted from the foregoing results that the combustion is quantitative, and also that the methane present remains unaffected.

Of the more recent publications on the estimation of carbon monoxide I can find only two worthy of notice. One by J. Tóth (Chem. Ztg., 1907, ix., 98), who employed the method elaborated by Kinnecutt and Sanford, for the estimation of CO in the smoke of tobacco. He filters the dried gases through cotton-wool, and before passing them through the pentoxide tube contained in a glycerin bath of 60° to 70° C., he purifies them in succession with 10 per cent caustic potash, baryta water, sulphuric acid, and quicklime.

The other publication by Morgan and McWorther | olefines passing to the iodine pentoxide tube, where, of (Fourn. Am. Chem. Soc., 1907, xxix., 1589) deals ex- course, they are oxidised, liberating correspondingly large haustively with the subject. They confirm that with amounts of iodine. We have proved this to be the case Kinnecutt and Sanford's method good results can be ob- with synthetical gas mixtures containing as little as 0.251 tained. Subsequently, however, they used a modification per cent ethylene. In the course of our investigations it of the method, which consists in passing the gas, after it has been found that, although by increasing the number of has left the iodine pentoxide tube and been freed from all sulphuric tubes and by keeping them at a temperature of .odine fumes, through a long test-tube containing barium- 160° to 170° C., the amounts of ethylene passing on were 'hydroxide solution of known strength, titrating the excess decreased; complete retention was only achieved by emof alkali with oxalic acid, using phenolphthalein as indicator. ploying sulphuric acid of a strength of 99 to 99.5 per cent They have proved experimentally that this method agrees H2SO4 and keeping the bulbs containing it at a temperawell with the titration of the iodine caught in potassium ture of 165° C. iodide. They make much of the fact that lubricants used for the glass stoppers of the iodine pentoxide tube have a tendency to creep inside, thus upsetting the accuracy of the results; as, furthermore, the employment of rubber or cork stoppers is, of course, out of the question, they express their surprise that none of the other investigators of the subject have found it worth while to draw attention to this matter. The authors, in order to get over this difficulty, have employed and recommend the radical measure of doing away with glass stoppers altogether, by using sealed glass connections only, and there is no doubt this does away with all chances of the lubricant interfering with the reaction.

As these measures have not been strictly followed in our experiments, it might not be out of place to mention our reasons for departing from them. In the first instance, a tube with the iodine pentoxide enclosed was not available, and we also foresaw some difficulty in removing the sublimed iodine quantitatively from the inner walls of the delivery tube. On the other hand, a spiral tube, such as Prof. Will had first of all employed for decomposing nitrocotton (Zeit. Angew. Chemie, 1901, 743), offered very great advantages both as regards handling and working. We found that, provided the hood is clamped to the body by means of springs (see H in illustration) the joint holds absolutely tight without the use of any lubricant. The large and well ground surfaces in connection with the above arrangement being so close fitting, also effectually prevent the tendency of the oil from the heating bath to creep up. This has been proved not only by the consistency of our results and the close agreement of analysis of synthetical gas mixtures, but also by repeated "blanks," extending over periods of several hours.

From all the foregoing it is clear that, although a great amount of research work had been carried out, there is a good deal of contradiction between the opinions of various workers, particularly with reference to the effect of certain gases, and also to the final determination of the products of the reaction. As regards the main principle of the method there is, however, only one opinion, viz., that the reaction involved by the passing of the CO over iodine pentoxide at temperatures from 70° to 150° C. is admirably suitable for its quantitative determination, and cannot be surpassed as regards delicacy and accuracy of the results obtained. Our decision, therefore, in selecting this method for the estimation of CO in mine gases should not require further justification.

The modifications introduced and the arrangement of the apparatus finally employed by us are the outcome of numerous experiments and extensive research, covering practically all the ground traversed by previous investigators. These experiments are too lengthy and complicated to be elaborated upon in these pages. Suffice it to say that by check-analyses, blanks, employment of synthetical gas mixtures, and all other means at our disposal, we have verified the accuracy of the results obtained. As an example, I will only mention that in a gas mixture containing o'999 vol. per cent CO and 400 vol. per cent CO2 and approximately known quantities of methane, ethylene, hydrogen, nitric moxoxide, oxygen, and nitrogen, we found o'97 vol. per cent CO and 4'11 vol. per cent CO2.

One other point might be specially mentioned, and that is the fact that ordinary sulphuric acid, even when as many as three absorption coils are used, does not prevent

In now describing the actual apparatus, it will be observed that provision has been made to keep the pressure within it at figures very little above the normal. This state of affairs ensures against undue strain being put on the various connections and joints, and is effected by the aspirator, M, taking off part of the resistance which the gases displaced from the sample bottle have to encounter. The two-way tap, T, in front of the mercury gauge, B1, which latter, by means of a vernier and mirror reflector, can be read to within o'r mill., allows of filling the apparatus with dried and purified air. The air used for this purpose has passed the chloride of calcium tower, x, the Liebig bulbs, y, containing palladious chloride, and the washing and drying apparatus, z, which contains caustic potash solution and soda-lime. At the end of the operation, when the required amount of gas sample has been taken, the whole apparatus is again flushed out with pure air until all of the sample has been displaced.

The gases in their course to the iodine tube, H, pass first of all a U-tube, B, filled with glass-wool and pumice saturated with sulphuric acid, in order to keep back organic and inorganic dust and moisture. They next pass through Liebig bulbs, c, filled with 99 per cent sulphuric acid, kept at a temperature of 165° C., and then through the sulphuric acid spiral, D. The gases now go through the carbonic acid absorption apparatus, which consists of the caustic potash bulb, E, the sulphuric acid spiral, F, and a U-tube, G, filled with pumice moistened with sulphuric acid. This arrangement was found necessary, as accurate results with the usual bulbs with calcium chloride tube attached were not obtained. The iodine pentoxide spiral tube, H, through which the gas next passes, is contained in an oil-bath at a temperature of 150° C. As will be seen the delivery tube dips directly into the absorption tube, L, containing 5 cc. of a 15 per cent potassium iodide solution. The gases finally are dried in the U-tube, 1, and the CO2 formed by the reaction is caught in the small apparatus, K.

If H2S be suspected in the sample an absorption tube containing acidulated lead acetate solution, or a tube containing pumice saturated with copper sulphate and dried at 150° C., must be inserted in front of the first sulphuric bulb.

In cases where methane is present, we have estimated it in a porcelain tube containing copper oxide by the ordinary combustion method. This tube in such instances was inserted between the aspirator bottle and the end of the apparatus just described. With this I bring my remarks on the methods employed by us to a conclusion. (To be continued).

THE FERMENTATION INDUSTRIES.
THE inaugural lecture of the courses of instruction on the
Fermentation Industries, held at the Sir John Cass
Technical Institute, Aldgate, was given on Tuesday,
October 5th by Mr. A. R. Ling, the lecturer on Brewing.

Dr. A. L. STERN, of Messrs. Bass, Ratcliff, and Gretton, presided, and in urging the importance of scientific investigation he met the criticism that such work should not be wasted on such a commonplace subject as brewing by the reminder that Pasteur's great work on bacteriology which in itself has done so much to alleviate human suffering, and was the pioneer work of an immense amount of in

MANCHESTER LITERARY AND PHILOSOPHICAL the absorption of a large number of gelatin filters prepared

will commend itself both to teacher and student. For one | CHEMICAL NOTICES FROM FOREIGN thing, it is more interesting than the general run of similar books, and the connection between scientific knowledge and every-day practice is constantly emphasised.

The

SOURCES.

"chemistry of daily life" is met with in every chapter Comptes Rendus Hebdomadaires des Séances de l'Académie

and much miscellaneous information which is certain to make an impression on the student's mind is included. The illustrations are of the type now commonly adopted in new geographical books, and although their bearing on the text is not always very apparent, the interest of the reader may sometimes be stimulated by them. A full year's course of theoretical and descriptive work is contained in the book, the text of which is to a certain extent marred by a somewhat florid and sensational style of writing. In an appendix each chapter is epitomised so that the chief facts in it may be rapidly revised, and also a set of questions is given on the subjects of every chapter; these appear more than ordinarily futile, for no attempt is made in them to exercise the student's power of thought and reasoning. The only possible use for them is to help the student to grasp the gist of each paragraph more readily, but this is really unnecessary, for the style is easy enough to present no difficulties even to the youngest beginner.

Aids to the Analysis of Food and Drugs. By C. G. MOOR,
M.A. (Cantab.), F.I.C., and WILLIAM PARTRIDGE, F.I.C.
Third Edition. London: Baillère, Tindall, and Cox.

1909.

des Sciences. Vol. cxlix., No. 5, August 2, 1909. Latent Heat of Fusion and Specific Heat of Propionic Acid.-G. Massol and M. A. Faucon.-The latent heat of fusion of propionic acid is found by experirelations of Raoult, van't Hofi, and Forcrand would give ment to be 23 35 cal. (for I grm.), whereas the general rather higher values. The specific heat in the solid state, taken between 46° and 19.8°, is equal to o·728; i.e., it is higher than the specific heat in the liquid state. These different results can be explained by the fact that for substances which have recently been solidified the liberation of the latent heat is not complete.

Ethylenic Derivatives containing Nitrogen.-G. Busignies. When the organo magnesium derivatives of alkyl halogens, in which the halogen group is united ketones, basic ethylenic amines are obtained. with CH2 or CH, reacts with amido- or alkyl-amido Thus the two compounds CH2=C= [C6H4-N-(CH3)2]2 and CH3-CH-C=[C6H4-N-(CH3)2]2, fusing at 115° and 99° respectively, can be obtained by this method. The that both they and the saturated compounds derived from author has prepared many similar products, and has found them by the fixation of two atoms of hydrogen have very marked basic properties. They are insoluble in water, soluble in organic solvents and in dilute acids, giving salts and double salts.

MISCELLANEOUS.

In this book, the third edition cf which has been thoroughly revised and almost re-written, short descriptions are given of the usual methods of analysing and detecting the presence of adulterants and impurities in common articles of food, and some notes are added on the British Pharmacopoeia and methods of testing a few drugs. Microscopical tests are either neglected altogether or else are very shortly-Louis Wertenstein.-The author has studied the diftreated, and a serious defect with regard to them is the absence of illustrations; it is practically impossible to give a satisfactory verbal description of the different forms of starch, for instance. It is, moreover, not difficult to find places in which the authors have dismissed processes of importance rather summarily; for example, Hinks' quali tative test for the detection of cocoa-nut oil in butter, which is merely mentioned, is a very useful method, well worth detailed notice, and Hanus' test for the same purpose also seems reliable. The colouring matters used for milk are very shortly treated, but at the same time the book does not aspire to completeness, and as a supplementary aid the third edition will serve the same useful purpose as its predecessors.

Action of Gravity on Induced Activity of Radium. ference in the active deposits on the two faces of two horizontal plates facing one another, as a function of the time which has elapsed since the action of the emanation ceased. He found that the induced activity which is deposited by the action of gravity contains no radium A, and this experimental fact can be explained by supposing that the fall of the deposit takes enough time to allow of the disappearance of the radium A. Using Debierne's apparatus for the study of the change brought about by the action of gravity in the shape of the curves which represent the value of the activity of the discs as a function of their distance, the author found that the surfaces turned downwards had a maximum of activity for distances between I cm. and 15 cm., and the activity diminished as the distance increased. The upper surfaces had activities proportional to their distances for small distances, and equal to those of the corresponding faces turned downwards; as the distances increased the shapes of the curves depended upon the moisture of the air and fell into three different classes. When the distance between the plates was such would lose all its activity during its fall, the activity of the that a particle in falling from one surface to the other face turned upwards ceased to increase with the distance. By using Stokes's Law to calculate the diameter of the particles it may be shown that in certain cases they may attain ultra-microscopic dimensions.--Comptes Rendus, cxlix., No. 4.

Analyse des Metaux par Electrolyse. ("The Analysis of
Metals by Electrolysis"). By A. HOLLARD and L.
BERTIAUX. Paris: H. Dunod et E. Pinat. 1909.
THE theory and principles of the separation of metals by
electrolysis are very simply stated in this book, in which
an attempt is made to present a rational classification of
the metals to serve as a basis for their separation by
electrochemical methods. General methods of separation
are discussed in the first part, and then the most important
metals are treated individually, full experimental details of
the processes employed being included. Applications to
industrial products form the subject of the third part of the
book, and very useful tables of experimental results are
given. Although important and valuable additions have
been made to the second edition the treatment of the
subject still remains very slight in comparison with that to
be found in the standard laboratory text-books of electro-
lytic analysis. However, the details of many methods of FRIDAY,
separation are arranged in the book in convenient form,
and the authors vouch for the reliability of all the processes
described.

WEDNESDAY,

MEETINGS FOR THE WEEK.

20th.-Microscopical, 8. "Microscopical Structure of an Inoceramus Limestone in the Queensland Cretaceous Rocks," by F. Chapman. Exhibition of Slides of Foraminifera from the Collection of the late Wm. Kitchen Parker.

22nd.-Physical, 5. "Cadmium Amalgams and the Normal Weston Cell," by F. E. Smith. "Production of Helium from Uranium and Thorium" and "Production of Radium from Uranium," by F. Soddy. "A Gravitational Problem," by C. V. Burton.

Generation can be stopped instantly by simply turning
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