Single crystals of trigonal NH4SnF3 with dimensions up to 3 cm were grown from aqueous solutions by the technique of controlled evaporation of the solvent. The crystals possess space group symmetry R3¯m. Their lattice dimensions are a = 6.839Å and c = 15.884Å with Z = 6. The optical, elastic, thermoelastic and thermal properties were measured. The elastic constants are by a factor 1/4 smaller than those of LiBaF3 or KMgF3. These differences must be attributed to specific interactions between bivalent tin and fluoride ions as in SnF2.

Large monocrystals of monoclinic SnF2 with dimensions up to 4 cm were grown from water solutions for the examination of their physical properties. Two different techniques were used: growth by lowering temperature (50 to 25°C) and growth by isothermal evaporation of the solvent (50 °C).

Abstract All elastic and thermoelastic constants and the coefficients of thermal expansion of monoclinic SnF2 are measured. These properties deviate strongly from the behaviour of other difluorides such as CaF2 and MgF2. The high anisotropy, the large bulk compressibility and the departures from the Cauchy relations suggest the existence of strong covalent binding components between tin and fluorine atoms. The thermal properties are in accordance with Grünseisen's rule.

Acid-set silica hydrosol, hydrogel, and the dried desiccant silica gel have been characterized by various types of measurements and discriminating tests. Acidic silica hydrosols have a molecular weight of about 2,000 at formation and reach about 2,500,000 at the point of gelation. Molecular growth of silicic acid in this hydrosol was found to be linear. Cross-linking of the polysilicic acid chains occurs in the hydrogel state, and the number of cross-links between chains have been estimated. Silicic acid bonding in acidic hydrosols is believed to be by hydrogen bonding between the silanol groups through water. The siloxane bonding in hydrogels aged beyond syneresis was determined by a depolymerization rate study; a low degree of siloxane type bonding was found. To account for the remaining bonding in the hydrogel, a high degree of hydrogen bonding is suspected. The reasons for hydrogen bonding are given. Most of the silanol condensation must occur during the drying of this type silica gel.

Journal of the Society of Dyers and ColouristsVolume 30, Issue 4 p. 128-134 Naphthol AS and its Application in Dyeing and Calico Printing FELIX KUNERT, FELIX KUNERTSearch for more papers by this authorE. ACKER, E. ACKERSearch for more papers by this author FELIX KUNERT, FELIX KUNERTSearch for more papers by this authorE. ACKER, E. ACKERSearch for more papers by this author First published: April 1914 https://doi.org/10.1111/j.1478-4408.1914.tb03697.xCitations: 1AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinkedInRedditWechat Citing Literature Volume30, Issue4April 1914Pages 128-134 RelatedInformation