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Notes: The pathology and bacteriology of an aeromonad epidemic in the spawning population of brown trout (Salmo trutta L.) of the freshwater Loch Leven, Kinross, Scotland, is described, together with estimates of its quantitative effect on the stock of trout.

Notes: Abstract Measurements have been made in the temperature range 0.5–5 K of the specific heats of pure solid H2, pure solid D2, and four solid mixtures of H2 and D2 with D2 fractions between 15 and 95%, all of which systems had low concentrationc of molecules in the rotational stateJ=1. For the H2,c=0.0023, and for the D2,c=0.030. It was found that the observed specific heats could be described as the sum of three terms as follows. (1) A lattice specific heat. This was found to follow aT 3 function with θ D =122 K for solid H2 and θD=113.8 K for solid D2. For the solid mixtures the lattice specifi heats have in first approximation values given by a weighted mean of the lattice specific heats of the pure components. (2) A Schottky term with a maximum at about 1.3 K for solid H2 and 1.4 K for solid D2, which can quantitatively be described in terms of electric quadrupole-quadrupole (EQQ) interactions in nearest-neighbor pairs and triples of molecules in the rotational stateJ=1. This term led to evaluation of г, the EQQ interaction energy, giving г/k=0.9 ± 0.1 K for solid H2 and 0.93 ± 0.05 K for solid D2. It was found, moreover, that in solid H2 there was an appreciable enhancement with time of the number of clusters of molecules in the rotational stateJ=1 at the expense of the number of isolated singles of similar molecules, due to rotation diffusion. On the other hand no rotation diffusion was observed in solid D2 or in the solid mixtures of H2 and D2, except possibly in those mixtures containing 85% H2. (3) A second anomalous term occurring at temperatures below about 0.8 K and, by extrapolation, having its maximum below 0.5 K (the lowest temperature of our measurements). This anomaly was observed only in those samples containing D2 and is, as yet, unexplained in detail. A further major conclusion from our results in the temperature range 0.5–5 K is that there was no evidence in the form of a sharp anomalous jump in the specific heat of any of the mixtures which could be interpreted as indicating the occurrence of isotopic phase separation. This absence of phase separation is noted, in spite of the fact that thermodynamically it is energetically favorable in the temperature range of observation.

Notes: Abstract An anomaly has been observed in measurements of the specific heat at saturated vapor pressureC s of pure, solid D2 of low para-D2 concentration below0.6 K. The new anomaly has been interpreted as evidence for the significance of electric quadrupole-quadrupole interaction between next-nearest-neighbor pairs of para-D2 molecules.