The ignited lead molybdate dissolved entirely in hydrochloric acid, thus showing that the precipitate was not contaminated with silica or insoluble material. If vanadium is suspected to be present in the ore, the solution of dissolved lead molybdate can be tested for vanadium by means of hydrogen peroxide. The solution will become reddish brown if any vanadium is present, from the formation of pervanadic acid (HVO). This is a very delicate reaction.

Vanadium is precipitated from solution as lead vanadate in precisely the same manner as lead molybdate. The lead vanadate, however, is not weighed, but the vanadium is calculated as in the determination for molybdenum, because the ccmposition of the precipitated lead vanadate is not always definite. The determination of vanadium and molybdenum when occurring together is described elsewhere in this paper under "Separation of Molybdenum from Vanadium."

(To be continued.)

REPORT FOR THE YEAR 1919

OF THE

FOOD INVESTIGATION BOARD DEPARTMENT OF SCIENTIFIC AND INDUSTRIAL

RESEARCH.

(Continued from p. 237.)

SOME of the main results of the preliminary chemical study of the cell saps of the apples stored under the two sets of conditions are :-(1) there is a marked disappearance of cane sugar during the earlier stages of storing; (2) the ratio of acids to sugars shows a decided fall towards the end of the period of storage; (3) there is a

sudden rise in the content of sugar and of acid in both sets of apples at about the tenth week; (4) the tissue changes which are associated with "rotting" of the apples are not accompanied by any marked change in the composition of the sap; (5) the sugar content of the apples from ordinary storage is consistently higher, in spite of their more rapid respiration, than that of the apples from cold storage.

The work in progress consists of (a) a more complete analysis of the carbohydrates present; (b) the relation between the amounts of pectin present in the juice and the cell wall; (c) the In relation of free and combined organic acid. connection with this work, Dr. S. B. Schryver has investigated a method for the determination of small quantities of methyl alcohol with a view to the estimation of the pectin.

Dr. W. Brown has been engaged at the Imperial College of Science and Technology upon a determination of the minimum temperatures for the growth of the fungi commonly occurring in fruit storage, where also an examination of the effect of the amount of available nutrient on the position of the minimal temperature has been carried out.

The effect of various concentrations of carbon dioxide on the germination and the growth-rate of fungi on different culture media at various temperatures has also been studied.

At Long Ashton, Professor B. T. P. Barker and Mr. C. P. Dutt have concentrated their attention upon the chemistry of the process of ripening in fruit. It is believed that the keeping qualities of fruits are largely affected by the changes undergone by their pectin contents. Since Fremy's original investigations on this subject little work has been done in this direction, and the present investigation has been undertaken with the object of obtaining further information on the nature of these substances and their significance in ripening. The work done during the last fruit season may be grouped under the following heads :(1) Chemistry of Pectins.

(2) Enzyme action.

(3)

Histological and microchemical observations.

(1) It appears well established that the tissues of unripe fruit contain material insoluble in water which, as ripening proceeds, undergoes change and yields a compound or compounds soluble in cold water and precipitable from aqueous solution by alcohol in characteristic gelatinous form. Fremy and most of the earlier subsequent workers on the subject have referred to the initial insoluble material under the name of pectose, and have termed the soluble product pectin. The latter, according to Fremy, undergoes a series of further changes as ripening proceeds resulting in the presence in ripe fruit of a complex mixture of substances, which he claims to have isolated, and the characters of which he has described in some detail. Notwithstanding the work of numerous investigators, there is at present no general agreement as to the chemistry of the group, and there is still uncertainty as to which, if any, of Fremy's products are definite compounds, and which are mixtures of a more or less complex character. No other worker has followed in detail the series of changes in the pectinous contents of fruit

Nov. 19,

iring ripening, and it seemed desirable therefore the outset of the present investigation to conrm, if possible, Fremy's observations as to the eneral character of the changes before investiating the nature of the change at each step of he series more closely.

The following notes serve to indicate the results bserved, which in general are as described by remy. For the sake of convenience of descripon his nomenclature has been largely followed, ut it must be understood that this does not imply sine acceptance of his views as to the existence of he substances referred to as definite chemical ompounds.

In early stages of ripening an aqueous extract of fruit tissues gives little or no gelatinous preipitate with alcohol. This precipitate, indicating he presence of water-soluble pectin, begins to appear when the fruit softens and increases in amount as the fruit ripens. In later stages of over-ripeness the amount of pectin decreases, and it may disappear altogether.

The properties and reactions of the pectinous material have been studied at different stages during the above series of changes, and have been found to agree closely with the properties and reactions of the products obtained by the chemical duhydrolysis of pectin.

In the water soluble stage, precipitable by alcohol, the amount that can be precipitated by neutral lead acetate solution (corresponding to Fremy's parapectin) was found to increase ripening proceeds. In the over-ripe stages precipitation with barium chloride was possible in some cases (corresponding to Fremy's metapectin).

as

The formation of an insoluble product by the action of acid or alkali on pectin corresponds to the formation of an insoluble pectinous substance by the action of the enzyme pectase on pectin solutions. In typical cases the gel, when first found by the action of pectase, is soluble in hot dilute acid, and, after treatment with acid in the cold, is soluble in boiling water, the solution giving a jelly on cooling. This jelly corresponds in its properties with the pectesic acid of Fremy. On standing the gel produced by pectase action usually contracts with extrusion of liquid and in this stage is insoluble in acid, or subsequently in water. The insoluble substance after treatment with acid corresponds in its properties with the pectic acid of Fremy.

This "pectic acid" dissolves readily in solutions of many neutral organic salts such as ammonium Oxalate. The solution in ammonium oxalate yields a gelatinous precipitate with alcohol which has many points of resemblance to the "pectinogen" prepared by Dr. S. B. Schryver.

The disappearance of pectin from the fruit seems to be accompanied by an increase in the amount of an acid substance which is soluble in water but not precipitable by alcohol, and agrees in its properties with the product obtained by continued hydrolysis or pectin by acid, which was described by Fremy under the name metapectic acid.

(2) Evidence has been obtained of the activity of an enzyme concerned in the production of soluble pectin from the insoluble substance of the cell wall.

Experiments have been made on various fruits at different stages of ripeness, but it has not been

found possible up to the present to isolate the enzyme having this action. By using expressed juices, water extracts of fruit and tissue residues after the expression of the juice, water extracts of fruit and tissue residues after the expression of the juice, evidence has been obtained which indicates the presence of a pectose-dissolving enzyme. For the most part soft fruits and plums have given negative results, but successful experiments have been made with apples and pears. Further experiments with these fruits are in progress.

Some study has also been made of the conditions under which the enzyme pectase is able to act on pectin solutions yielding an insoluble pectinous substance. In some cases, a jelly-like clot of this material is produced, the formation of which is dependent on the concentrations of pectin and pectase and on the presence or absence of acids or other inhibiting substances.

The setting action of pectase is destroyed by heating to a sufficient temperature. For a comparison of the activity of the pectase in different fruits experiments were made to determine the upper temperature limit. The pectase power of different fruits varied considerably, the chief determining factors being probably :(a) the amount of pectase;

(b) the presence of inhibiting substances. Usually the ripe fruit was most active.

On the whole, the action of the pectase of the unripe fruit is inhibited by heating to a lower temperature than required by the ripe fruit.

(3) Some observations with the microscope were made on sections of fresh material, particularly by means of a staining reaction with ferri ferricyanide, which depends on the reducing power of pectin compounds.

It has been found that observations could be made as exactly and more conveniently on material preserved in alcohol and sectioned in paraffin wax by the usual microtome method. For the various fruits studied, therefore, a progressive series at different stages of ripening has been preserved in alcohol so as to be ready for use when required.

(To be continued).

PROCEEDINGS OF SOCIETIES.

ROYAL SOCIETY.

Ordinary Meeting, November 4, 1920.

Sir J. J. THOMSON, O. M., President, in the Chair. THE following papers were read :

"Vibrations of an Elastic Plate in Contact with Water." By Prof. H. LAMB.

The chief problem considered is that of determining the gravest frequency of a thin elastic diaphragm filling an aperture in a plane rigid wall which is in contact on one side with an unlimited mass of water. This had an interest in connection with submarine signalling. An exact solution is not attempted, but a sufficient approximation for practical purposes is obtained by Rayleigh's method of an assumed type, which gives good results if the type be suitably chosen. The rate of damping owing to the loss of energy

(i)

"The Transmission of Electric Waves around the Earth's Surface." By Prof. H. M. MACDONALD.

"A Re-examination of the Light Scattered by Gases in respect of Polarisation. II.-Experiments on Helium and Argon." By Lord RAYLEIGH, F.R.S.

The light scattered by helium and by argon is investigated. It is found in the case of helium that the total light scattered is in accordance with what would be expected from its refractivity. The polorisation in helium, contrary to what was found in 1918, is approximately complete. No intensity was detected in 24 hours of exposure in the component vibrating parallel to the exciting beam, and certainly this component was less than 65 per cent of the other.

Argon polarises much more completely than any other gas examined, with the possible exception of helium, the weak component being only 0.4 per cent of the other.

"Dilatation and Compressibility of Liquid Carpressibility of Liquid Carbonic Acid." By Prof. C. F. JENKIN.

The paper describes the measurement of the dilatation and compressibility of carbonic acid between temperatures of 37° C. and +30° C. and up to pressures of 1400 lb. per square inch. The measurements were made to supply accurate data for determining the starting point for drawing the 0 and Ip diagrams and to replace the approximate results (known to be inaccurate) given in a former paper (Phil. Trans., A, ccxiii.,

76).

The apparatus consists of an inverted burette dipping into mercury, the whole enclosed in a steel cylinder. The volume occupied by the CO2 in the burette was indicated by the resistance of a long loop of platinum wire, short circuited at the bottom by the mercury. The temperature was indicated by a second platinum wire, wound round the upper end of the burette, used as the "bulb" of a platinum thermometer. The pressure shown by a large calbrated bourdon pressure gauge. The results are given in tables and curves showing (1) the specific volumes of CO, at varying pressures and temperatures; (2) the true

dv

was

CO

efficients of expansion {}; ; and (3) the true

ข dt

coefficient of compressibility,{},

The investigation was undertaken for the Food Investigation Board (Board of Scientific and Industrial Research).

"Radiation in Explosions of Hydrogen and Air." By W. T. DAVID.

This paper contains a record of the results of experiments on the emission of radiation during the explosion and subsequent cooling of mixtures of hydrogen and air contained in a closed vessel. The results of experiments on the transparency of the exploded mixtures are also recorded. Some

(ii)

(iii)

The rate of emision is approximately pro portional to the fourth power of the absolute mean gas temperature. The maximum rate of emission occurs at the point of maximum temperature. The exploded mixtures are very transparent throughout cooling to radiation of the same kind as they emit. (iv) The intrinsic radiance increases both with the lateral dimensions and with the thickness of the radiating layer of gas. The 28μ band of steam ceases to be emitted when the gas temperature has fallen to about 700° C.

(v)

The experiments indicate that radiation phenomena in the hydrogen mixtures are in general similar to those in coal-gas mixtures (Phil. Trans., A, ccxi., 375-410). In one or two respects, however, there are important differences, the most noticeable of which perhaps is, that in the hydrogen mixtures the maximum rate of emission occurs at the moment of maximum temperature, whereas in the coal-gas mixtures it occurs during the explosion period (during which the bulk of combustion takes place). This is of interest in its bearing on the nature of combustion.

The ceasing of the emission of 2.8μ radiation after the gas temperature has fallen to about 700° C. indicates that the vibratory degrees of freedom of the steam molecules corresponding to radiation of this wave-length, share in the heat energy of the molecules only at temperatures above 700° C. This would appear to account for the rapid rate of increase of the specific heat of steam which begins to take place in the neighbourhood of this temperature.

"Photochemical Investigations of the Photographic Plate." By R, E. SLADE, D.Sc., and G. I.

HIGSON.

perature at the same Level in the Free Atmos"The Relationship between Pressure and Temphere." By E. H. CHAPMAN, D.Sc.

The paper deals with the exceptionally high values contained in the table of coefficients of correlation between changes of pressure and changes of temperature at different levels in the atmosphere included in Geophysical Memoir 13 of the Meteorological Office, by W. H. Dines. The coefficients are computed for observations taken at random, and arranged in four groups for the year, of three months each.

For the layers between 4 kilometres and 8 kiloIt is assumed that if the observations were freed metres these coefficients range from o'75 to 0.92. entirely from errors of measurement the coefficients would be still higher. A method is therefore worked out for correction of coefficients of correlation for probable errors of observation in measurement.

An estimate is formed of the extreme values of the errors and the probable errors in the measurement of temperature and pressure in the atmosphere by an examination of the results obtained by Dines in England and Blair in the United States, and from the values a table of ratios for the correction of the crude values of the several coefficients is obtained. The final table of coefficients for the range from 4 kilometres to 8 kilometres, as corrected for probable errors of observation, contains 20 values each referring to 3

1920 months. All of the 20 trimestal values thus reated come out greater than o'84, 18 of them exceed 09, and 3 of them reach the maximum -alue of 10.

Quartz is almost always present in veins along with one minerals, and silica often occurs in solution in thermal springs, especially such as carry gold, arsenic, antimony, and mercury. For these and other reasons it is regarded as probable that

INSTITUTION OF MINING AND METALLURGY.

October 21, 1920.

Mr. FRANK MERRICKS, President, in the Chair.

"The Origin of Primary Ore Deposits." By J. MORROW CAMPBELL.

The author commences at the period when the outer silicate shell of the earth was molten. The primæval magma is regarded as having been practically homogeneous and containing about 60 per cent of combined silicates. All water was then in the atmosphere giving a pressure over 300 times as great as at present. As temperature fell water and oxygen were absorbed; crust-formation, foundering, and resorption went on for a long period producing a flat temperature gradient in the liquid. Viscosity eventually rendered further foundering impossible, the crust became permanent, granite developed and below it the segregated basaltic magma long remained liquid. At this stage the isostatic balance was adjusted. Ore minerals in large quantity were given off at the surface of the granite; these were denuded and dispersed in sediments and solution. This, with subsequent absorption by intruded basic magma is assumed to have been instrumental in causing the present erratic distribution of primary ores. All so-called water in magmas is held to exist in combination as hydroxyl with silica not in solution as a gas.

Magmatic differentiation is regarded as having been caused by the agency of silicic acid-silicon combined with hydroxyl-which extracts potash alumino-silicate producing a solution lighter than and immiscible with a melt of basic felspars and ferro-magnesian minerals. It is believed that in this way the first great split of primary magma into the world-wide granitic and basaltic types was brought about.

Evidence regarding the existence of silicic acid in magmatic liquids and elsewhere in nature is recited.

The ultimate result of the action of water on rock magmas is that silicates are completely removed and a residue of ore minerals such as magnetite, ilmenite, and chromite left.

Vein fissuring was brought about in and above batholiths by the expansive force due to the increase in solid specific volume of various elements. This increase is very considerable, exceeding in amount the contraction on solidification of the granite, and continues throughout the whole of the crystallisation period. The effect of this force appears in waves as fissures in successsive series. These developed very rapidly, were instantly filled with magmatic mother-liquor and quickly sealed by the deposit of solids therefrom.

veins do so in silicic acid solution and possibly in combination. The deposition of these ores is usually caused by loss of heat and reduction of pressure. It is believed that there are definite but narrow limits of temperature between which each ore mineral develops. These correspond to the temperatures in the strata at the bottom and the top of the ore at the time of deposition. Ore persising for a vertical depth of 2000 feet would therefore indicate normally a temperature range of 20° C.

The pneumatolytic theory of the origin of the high temperature ores is rejected because the phenomena of their occurrence is quite inconsistent with what would result if these metals had been given off as gases by magmas. The boiling point of tungsten fluoride (19° C.) and tin fluoride (705° C.) are so far apart that it would be impossible for wolfram and cassiterite to have developed in contact with one another as they frequently do. Accessory minerals such as fluorite and tourmaline lose the genetic significance usually attached to them owing to the fact that they are not invariably present with tin and tungsten ores and are frequently associated with a variety of other ores which are admittedly of hydrothermal origin. tion to the probable importance of variations of In introducing the paper the author called attenpressure in ore solution and deposition. Separation from simple solution would involve deposition of ore along the whole upward course of the solvent. This does not take place, the end being usually abrupt in an upward direction. phenomena in nature seem to indicate that reduced pressure causes dissociation and, at some point, the total removal of ore from solution. High temperatures and pressures not entirely correlative, and, since they usually accompany one another in nature, it is possible that as regards ore deposition we may in the past have been confusing the two.

are

The

To the Editor of the Chemical News. SIR, The outer tube of this apparatus seems to be always of glass, for those which I have seen have been of that material, and text-books and apparatus makers' catalogues show glass. No doubt others have been troubled with students breaking the bottom of the outer tube, which is necessarily thin. I suggest to them that they should adopt a tube made of sheet copper, with a dished bottom, which can be used with water or any liquid which does not attack copper. A copper tube costs more than does a glass tube, but my experience has been that it soon proves itself more economical. Perhaps makers of apparatus may take the hint.-I am, &c.,

Technical School, Barnsley.

A. PRICE.

CHEMICAL NOTICES FROM FOREIGN SOURCES.

Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. No. 14 (October 4, 1920). HEAT OF OXIDATION OF GLUCINUM.-MM. H. Copaux and C. Philips.-The glucinum for the above research was prepared according to the method laid down by Lebeau (Compt. Rendus, 1898, cxxvi., 744). Many methods were tried by the authors before a satisfactory one was obtained. They first tried to determine the heat of oxidation of glucinum by direct combustion, but no satisfactory results were obtained, because there always remained behind some unconverted metal. They

tried the addition of a small quantity of vaseline, also using a known weight of cotton, but without any result. The addition of oxide of lead was also tried; this was found to be useless, for it left after combustion, small particles of reduced lead which had not reoxidised. The method they finally adopted was to measure the heat of solution of both the metal and oxide in the same acid. Hydrofluoric acid, being the only acid capable of dissolving both glucinum and anhydrous glucina quickly, was adopted. The following thermochemical equations will give the required heat of formation :

+ H2 + Q, + H2Oliq +Q1, → H2Oliq + 69 cal,

Gl + 2HFdiss→ GIF 2 GIO + 2HFdiss GIF 2 H2 + O

from which

Gl + O

Bulletin de la Société Industrielle de Rouen. Vol. 48, No. 2.

ALSATIAN POTASH SALTS.-In Alsace, potash deposits exist around Mulhausen, also around Wittelsheim. They extend from the north-east of Mulhausen to the foot of the Vosges Mountains, the best potash being found at a depth varying from 400 to 600 metres. The deposits have been estimated to contain 300 million tons of potash. The potash veins exist in alternate layers of red and grey colour. They are composed of a mixture of sylvine or potassium chloride and rock salt or sodium chloride, the mixture being known as sylvinite. The colour of the red layers is caused by oxide of iron; these veins are richer in potash than the grey veins, which contain a larger amount of rock salt. The content of KC1 varies from 20 per cent to 60 per cent. The Alsatian salts are very pure, containing little magnesium salts which are injurious in agricultural work, consequently they need only a simple grinding, differing from the Stassfurt carnallites which must necessarily be purified. Two specimens of sylvinite gave 14 per cent K2O (22 per cent KCl) and 20 per cent K,O (32 per cent KCI). complete account of the potash mines of Alsace is published in the Bulletin de la Société Industrielle de Mulhouse, No. 4, April, 1912).

(A very

NOTICES OF BOOKS.

1920.

Margarine. By WILLIAM CLAYTON, M.Sc. (Liverpool). Pp. xi.+187. London: Longmans, Green, & Co., 39, Paternoster Price 14/- net.

THIS volume adds one more to the "Monographs on Industrial Chemistry," edited by Sir Edward Thorpe, C.B., LL.D., F.R.S. The author, in this exceedingly interesting monograph, deals with a subject which has hitherto only been dealt with by other authors as a subsidiary subject, that is to say, only a few pages have been reserved to describe this important industry.

In an introduction is given a brief history of the industry, followed by a chapter on the "Oils and Fats used in Margarine Manufacture." The manufacture of margarine is next discussed, where is given the different processes adopted. illustrated by diagrams. The chemistry of its constituents is next discussed, and the methods of their analysis, as well as of the finished product. A chapter on "Nutritional Chemistry" deals with the recent investigations on the Vitamines.

A bibliography and an index complete a book which should prove useful to all who are interested in this industry.

NOTES.

CROP YIELDS OF THE NORTHERN HEMISPHERE IN 1920. The October Statistical Bulletin of the International Institute of Agriculture announces the aggregate results of cereal crops in most of the countries of the northern hemisphere. Data are now to hand from almost every quarter, with the exception of Russia, but as regards Europe comparisons with previous seasons cannot be made complete, owing to the numerous territorial alterations. The totals resulting from available and comparable data for the northern hemisphere sum up to 56.8 million metric tons of wheat, and 5-6 million tons of rye, in the aggregate 62.4 million tons. This quantity is slightly larger than the yield in 1919 (61.7 million) and identical with the average of the preceding five years. The comparable data for barley dealing with a number of countries producing just under one-half of the world's yield, make a total of 127 million tons, 8 per cent larger than the production of 1919, and The 5 per cent below the five years' average. yield of oats in countries furnishing all the required data (affording about 60 per cent of the world's yield) is estimated at 38.3 million tons, showing an increase of 21 per cent over last year, and 9 per cent over the average. The maize crops of South-Eastern Europe are reported as good, that of Italy as fair, while the United States' yield amounts to 817 million metric tons, 10 per cent over last year's, and 16 per cent above the average. Reports on the probable yield of beet sugar are favourable from Austria, Belgium, France, Germany, Italy, Netherlands, Sweden, and Canada, also for both cane and beet sugar from the United States. The export from British India of 400,000 tons of wheat has been sanctioned and will take place unless internal prices advance beyond the purchase limit officially fixed. The 1 weather in October has not been favourable for crop developments.