A- and B-type hydrogen bond modifications of potassium hydrogen tartronate
ACCORDING to Speakman1 two types of intermolecular hydrogen bonds between carboxyl groups can be discerned in the crystal structures of acid salts of carboxylic acids. The first, type B, occurs when two carboxyl groups are not symmetry related, and have structural differences sufficient to characterise them, separately, as unionised (−CO2H) and ionised (−CO2−). Thus, any hydrogen bond between these groups must be asymmetric. The second, type A, occurs when two carboxyl groups are related by a symmetry element of the crystal, so that they are effectively equivalent. Thus any hydrogen bond between the groups must be, at least formally, symmetrical.
Analyse vibrationnelle et structurale en série aliphatique saturée. 7—spectres de vibration de l'Acide hydroxymalonique et de ses sels alcalins en solution aqueuse
Les spectres Raman et infrarouges de l'acide hydroxymalonique et de ses sels alcalins en solution aqueuse (H2O et D2O) ont ete enregistres entre 100 et 4000 cm−1. L'analyse du facteur de depolarisation nous a permis de conclure que l'acide hydroxymalonique et le sel neutre appartiennent au groupe de symetrie Cs alors que le sel acide appartient au groupe C1. Une attribution des vibrations fondamentales est proposee. 
 
 
 
Raman and infrared spectra of hydroxymalonic acid and its potassium salts in aqueous solutions (H2O and D2O) were recorded from 100 to 4000 cm−1. The analysis of the polarization of the Raman lines indicated that hydroxymalonic acid and its dipotassium salt belong to the Cs group whereas the acid salt belongs to the C1 group. An assignment of the fundamental vibrations is proposed.
THE IDENTIFICATION AND ISOLATION OF TWO MOUSE-TOXIC PROTEIN COMPONENTS IN EXTRACTS FROM PASTEURELLA PESTIS
The toxin activity of Pasteurella pestis cells, strain "Tjiwidej," was found to be associated with two proteins. Using a disc electrophoresis technique in conjunction with mouse lethality, two toxic proteins were isolated exhibiting intraperitoneal LD 50's of less than 1.0 to 1.5 µg protein. Each produced a single characteristic precipitin band on agar gel diffusion plates. The slower migrating toxin in gel diffusion or disc electrophoresis was designated as toxin A. It was shown to be sensitive to deoxycholate and digitonin, did not accumulate in 5-fluorotryptophan treated cells, and was associated with the membrane fraction of the cell. The faster migrating toxin B, apparently is resistant to surface-active agents, and is not affected by treatment of cells with 5-fluorotryptophan. Toxin B is associated with the soluble or cytoplasmic fraction of the cell. This evidence suggested that each toxin represented a distinctly different molecular species. The possibility is discussed that toxin B is synonymous with the murine toxin previously isolated by paper curtain electrophoresis which revealed only one antigen band in the Oudin precipitin reaction.