Abstract: Tabular grain emulsions are disclosed in which the tabular grains have average thicknesses of less than 0.07 .mu.m and average equivalent circular diameters of at least 0.7 .mu.m. These ultrathin tabular grain emulsions are improved by the incorporation of at least 0.4 mole percent chloride along with >50 mole percent bromide and, optionally, iodide. Greater than 97 percent of total grain projected area can be accounted for by the tabular grains. The emulsions exhibit reduced pressure sensitivity, exhibit increased developability and exhibit reduced native sensitivity to the blue region of the spectrum.

Abstract: A process is disclosed of preparing a high bromide high aspect ratio tabular grain emulsion. At least a portion of grain growth is conducted in a temperature range of from 30.degree. to 90.degree. C. within a low pAg window and, during the low pAg grain growth, precipitation is conducted in the presence of chloride ion, which acts to offsets tabular grain thickening attributable to grain growth in the low pAg window.

Abstract: A process for preparing a photographic emulsion involves an initial nucleation step of reacting a first silver salt with a bromide in the presence of a first excess halide under conditions effective to nucleate AgBr crystals. The nuclei are then grown to form photosensitive grains by addition of a second silver salt and a second halide as growth salts. If excess chloride is used during nucleation, even without excess bromide and/or a growth modifier, the nuclei formed have twin planes, and the pAg level can be used to control the aspect ratio of the tabular grains obtained. If a relatively high silver concentration in the growth solution is maintained throughout the growth step, the resulting grains have a unique, twinned cubooctahedral or cubooctahedral-tabular shape. Unique tabular grains having alternating 1.1.1 and 1.0.0 edge faces can be formed by this process.

Abstract: Tetra-substituted aryl cyclic formazan dyes are useful in assaying for lithium. The dyes have the structure: ##STR1## in which X represents CN or NO.sub.2 ;Y represents CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CH.sub.2 CH.sub.2 --O--CH.sub.2 CH.sub.2 ; andR.sub.1, R.sub.2, R.sub.3 and R.sub.4 each independently represent butyl, halogen, alkoxy or NO.sub.2.

Abstract: Novel tetra-substituted aryl cyclic formazan dyes are useful in assaying for Li.sup.+.

Abstract: An analytical composition, electrode and method are useful for the detection of lithium ions in an aqueous liquid. The lithium ion-selective composition comprises a lipophilic group-substituted 1,10-phenanthroline, a compound capable of solvating the phenanthroline, and a supporting matrix. This composition can be used in a lithium ion-selective electrode as a lithium ion-selective membrane. The electrode can also comprise an internal reference electrode.

Abstract: Ion-selective compositions which comprise an ionophore, a compound capable of solvating the ionophore and a supporting matrix are disclosed. The ionophores useful in these compositions are certain crown ethers. These ion-selective compositions are particularly useful in ion-selective membranes and electrodes which are capable of selectively transporting a first ion in preference to a second ion. Such compositions, membranes and electrodes are useful for potentiometric measurement of alkali metal ions, e.g. lithium, sodium and potassium, in aqueous solutions, e.g. biological fluids. Dry-operative electrodes using these ion-selective compositions as membranes are also disclosed.