As it is very difficult to expel completely all the carbon dioxide it may be concluded that this manganese corresponds to the residual carbonic acid. The oxides of manganese, when exposed to the action of a saturated solution of carbon dioxide, do not all dissolve to the same extent, the amounts dissolving at 13° (expressed in terms of manganese) being :— Protoxide Sesquioxide Dioxide 0'0291 grm. per 0'0046 0'0015 litre. The solubility depends upon the richness of the solution in carbon dioxide and upon the time. Humus, though rich in manganese, is not a solvent for all the oxides, the sesquioxide and dioxide not being attacked by it. In nature it appears that manganese is dissolved by the carbon dioxide liberated by fermentation in the soil, organic matter contributing to the solution by their decomposition. The fact that the commonest natural form of manganese is the sesquioxide explains the poorness of natural waters in manganese. Mineralised waters are richer, and the use of chemical manures favours the solution. No. 8, February 21, 1916. Presence of Reducing Substances other than Invert Sugar in Commercial Sugars.-L. Maquenne.-It is known that raw commercial sugars and even most refined sugars contain small quantities of reducing substances, and à priori it might be supposed that these substances consist of invert sugar. While, however, it is certain that invert sugar is present in ordinary sugar it has not been shown that it is not accompanied by other substances which are capable of acting upon cupropotassic liquid, and some observations tend to confirm this view. Thus alcoholic fermentation does not cause the disappearance of all the reducing substances in molasses. The author points out that these reducing principles are present in crystallised and refined sugars in a higher proportion than in the raw products, if this proportion is compared with that of the invert sugar which accompanies them. If it is admitted that they behave towards cupric liquid like saccharose rather than like reducing sugars proper, it would be found that the proportion of them is higher the higher the temperature. This is actually found to be the case, and when the estimation is carried out at 100° and at 65° by the author's method which has previously been described, and has been found to be applicable to the determination of invert sugar added to pure cane-sugar, the numbers obtained at 100° are appreciably higher than those found at 65°. If it is assumed that the greater part of the reduction observed at the low temperature is due to invert sugar the difference between the two determinations may be regarded as giving approximately the amount of secondary reducing substances. The weight of these reducing substances other than invert sugar is greater in sugars which contain much of this latter, but the ratio of these two quantities increases with the purity of the sugar. It appears to be impossible to determine exactly the amount of fermentable reducing sugars present when they are accompanied by secondary reducers, but the low temperature method gives an approximation to the truth, and is to be preferred by any other. Study of the Volta Effect by Induced Radioactivity-Establishment of Two New Facts.-Ed. Sarasin and Th. Tommasina.-The authors have continued the study of the Volta effect by induced radioactivity, using the apparatus already described by them, with some modifications. They have thus shown that when the electrodes are separated by air containing emana. tions and the radiations of induced radio-activity, and also when the electrodes (of copper and zinc) are in direct contact with one another, and also in contact with induced radio-activities and under the influence of an electrostatic charge, a current is produced. In the cases studied the current always passed from the zinc, and the radio-active medium behaved exactly like the electrolyte of a battery. New Thermo-electric Method of Studying the Allotropy of Iron and other Metals.-C. Benedicks.In a closed circuit composed of a homogeneous metal a change of temperature does not give rise to any electromotive force capable of giving a current. Moreover, if the metal possesses an allotropic point of two phases and one part of the circuit is heated in a stationary manner from that point no electromotive force results; the differences of potential of the two phases are mutually annulled for reasons of symmetry. If, on the other hand, the elevation of temperature is not stationary the two surfaces of contact between the phases may have a slight difference of temperature which may give rise to an electromotive force. Suppose that the heated zone is displaced along the current : the temperature of allotropic transition being always a little higher on heating than on cooling (Osmond), a constant electromotive force will be set up; it will depend upon the direction of displacement, the magnitude of the hysteresis, and the electromotive force between the two phases. Trouton has already shown that a thermopassed through a gas jet. The author has devised a simple electric current is produced in an iron wire when it is apparatus by which this effect can be measured. The iron wire is passed at a constant velocity (1.6 mm. per second) through a small electric furnace, which is kept at a constant temperature. Measurements are then made of the electromotive forces developed. In this way it was found that iron shows the point A3 very clearly, but no discontinuity was found for A2. MISCELLANEOUS. Royal Institution.-A General Meeting of the members of the Royal Institution was held on the 3rd inst., Sir James Crichton-Browne, Treasurer and Vice-President, in the chair. Mr. John Dewrance, Mr. Samuel Smiles, D.Sc., Mr. Arthur E. Parsons, and Mr. Samuel Nivison were elected Members of the Royal Institution. Royal Institution.-The Day Lectures after Easter:— Laurence Binyon, two lectures-(1) "Indian and Persian Painting"; (2) "Chinese Painting." Prof. Charles S. Sherrington, two lectures Harvey and Pavloff." Thomas Martin Lowry, two lectures-"Optical Research and Chemical Progress." Sir Ray Lankester, three lectures-"Flints and Flint Implements." Sir Alexander C. Mackenzie, three lectures-(1) "The Beginnings of the Orchestra and its Instrumental Combinations"; (2 and 3) "Chamber Music and its Revival in England." Prof. W. H. Bragg, two lectures -"X-Rays and Crystals: (1) New Methods of Research; (2) First Results and their Applications" (the Tyndall Lectures). Prof. H. S. 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