Infrared spectra in the Ag2O-CO2-Ag2CO3 system

The infrared spectrum of silver oxide, Ag2O, has been clarified by comparison with that of silver carbonate. In the region 4000-400 cm-l the spectrum consists of one broad band centred around 530 cm-l, other bands being accounted for in terms of normal, basic, and complex carbonates and surface hydroxyl groups, which are frequently present as contaminants. Conditions for the preparation, storage, and purification of silver oxide to minimize carbonate contamination are defined.

The reaction of methanol vapour with silver(I) oxide

The reaction of methanol with silver(I) oxide has been studied in the temperature range 56.5-78.4�. For complete reduction of the oxide at 78.4�, the available oxygen is fully accounted for by the products, formaldehyde, formic acid, carbon monoxide, carbon dioxide, and water. In the temperature range 56.5-70.2� the net measured rates of formation of these products are expressed by equations of the form, ������������������ rate = Aexp(-E/RT), and the kinetic data are interpreted as the consecutive formation of the products on the surface without complete desorption to the gas phase between each step. For the dominant product, carbon dioxide, at the mean temperature the values of A and E are 1028.5 μg oxygen per minute and 41.3 kcal mole-1 respectively. The former is interpreted in terms of a simple collision model and the latter compared with values obtained for the thermal decomposition of the oxide.

The Adsorption of Hydrogen on Silver(I) Oxide

Hydrogen is physically adsorbed on silver(I) oxide in the temperature range, 77-188�K, with an isosteric heat of 300 cal mole-1. The adsorption and desorption isotherms are described by a generalized equation of the Langmuir type with some departures at low values of the coverage. The specific rate of desorption is accurately predicted by the quantum mechanical treatment of physical adsorption. In the temperature range, 250-288�K, activated chemisorption described by the Elovich equation ensues with an activation energy of 5000+3000θ cal, where θ is the coverage. The parameters of the Elovich equation are comparable with those obtained for hydrogen on several other metal oxides.

The Development of Pandora inaequivalvis (Linné)

During an investigation into the functional morphology and habits of Pandora inaequivalis (Allen, 1954; Allen & Allen, 1955), successful artificial fertilization of the eggs was carried out and the larvae reared past metamorphosis to the dissoconch stage. As nothing is known of its development, nor that of any other member of the suborder Anomalodesmata, it seems desirable to describe the development and relate it to the habits of the adult. The adults of P. inaequivalvis, on the Brittany coast, are local in their distribution and occur in sheltered sandy bays where they lie at or very close to the surface of the sand at low-water mark. The problem of maintaining each population would seem to depend on some means of limiting the dispersal of the young. Such a limitation was found to occur.

Methods P. inaequivalvis is a hermaphrodite bivalve, the testis and ovary maturing at about the same time. The eggs and sperm are shed directly into the sea.

The Thermal Decomposition of Silver(II) Oxide

The thermal decomposition of silver(II) oxide in a vacuum has been studied over the range 83-134 OC. The rates are quantitatively accounted for by the Polanyi-Wigner equation, the values of the vibration frequency at all stages being within a power of 10 of the expected theoretical value. Changes in the rate at different stages of the reaction are interpreted in terms of diffuseness of the reaction interface. This conclusion is supported by X-ray and surface area studies. The activation energy is 30 kcal. The activation energy associated with the removal of oxygen from the first layer has been shown to be the same as that for the subsequent reaction.

The Sorption of Oxygen by Silver

The Gibbs adsorption equation has been used in conjunction with surface tension measurements on silver wires to determine the adsorption isobar of oxygen on silver at a pressure of 16 cmHg over the temperature range 650-850 �C. The results show the existence of a surface concentration of oxygen of 2 x 1015 atoms oxygen per cm2. The value of ΔH for the equilibrium between adsorbed and dissolved oxygen has been estimated as 20.6 kcal. This value in conjunction with the heats of formation and solution of Ag2O in silver permit the h3at of adsorption to be determined as 10.5 kcal per g-atom of oxygen.

The Thermal Decomposition of Silver(I) Oxide

The thermal decomposition of precipitated silver(I) oxide in a vacuum has been studied over the range 100-350 �C. Three regions are identified : in the fist, 100-200 �C, the activation energy is 30 kcal, 5 per cent. of the total oxygen is evolved, and the lattice parameter increases to a limiting value ; in the second, 200-300 �C, the activation energy is 50 kcal, and a further 1-2 per cent. oxygen is evolved; in the third, above 300 �C, metallic silver crystallizes, the oxide lattice contracts to a constant value, and the activation energy becomes 36 kcal. The activation energies in the three regions are interpreted as being associated, respectively, with (i) the diffusion of silver into the oxide lattice, (ii) the formation of aggregates of silver " atoms " not conforming to the normal silver lattice in an oxide lattice saturated with silver, and (iii) the reaction at the interface between metallic silver and the oxide.

FLUKE DISEASE IN NORTHERN MANITOBA SLEDGE DOGS

An opisthorchiid Trematode, Parametorchis manitobensis n.sp. is recorded from the livers of sledge dogs from northern Manitoba. A key is given to the known species of Parametorchis. Infection with the trematode produces chronic cirrhosis and anemia, followed by muscular weakness and death. Infection is believed to be contracted by ingestion of metacercariae in Catostomus commersonii and prophylaxis would consist of the thorough boiling of such fish before use as dog food.