BEAKERS of Kavalier glass, and beakers and flasks of Macbeth Evans Glass Co.., Pyrex, Jena, Nonso,1, Fry and Libbey glasses were tested for chemical composition, coefficient o,f expansion, refractive index, strain, behavior on repeated evaporation, resistance to heat and mechanical shock, and to solution in a variety of chemical reagents.
No. conclusions as to the relative values of the, different wares can be drawn from the chemical analyses, though these analyses may be useful by enabling the chemist to choose a glass which will yield no objectionable ingredient to the solutions used in any particular piece of work. The coefficient of expansion of all the glasses is low and is unusually so in Pyrex ware. All the ware shows more or less strain, but it was disappointing to find that no information as to liability to break under sudden changes in temperature or mechanical shock coaald be obtained by an examination for strain. All the ware tested showed good resistance to repeated evaporation of a salt solution. While the heat and mechanical shock tests were performed on too small a number of pieces to justify positive conclusions, they indicated that the Kavalier and M. E. G. Co. ware are less resistant than Jena, Nonsol, and Fry wares, the Li,bbey somewhat more resistant and the Pyrex ware distinctly more resistant. The Kavalier ware is unsatisfactory as regards solubility in water ; all the other wares appear satisfactory in this respect. All the ware is resistant to acids, Kavalier is least resistant to carbonated alkalies, Pyrex more resistant than Kavalier but less resistant than the others. Kavalier and M. E. G. Co. wares are more resistant to boiling caustic alkaline solutions than the others but the differences are not great. All the glasses are much attacked by evaporating caustic alkalies. Ammonia water has about the same effect as mixtures of ammonium chloride and sulphide. The authors are of the opinion that considering all the tests each of the American wares is superior to, the Kavalier and equal or superior to the Jena ware. * Communicated by the Director. 1 Technologic Papers of the Bureau of Standards, No. lO7. 827