A method for determining the composition of a fluid by using measured properties of the fluid. The material is characterized by having a composition selected from the group consisting of RE3Ga5\u2212xAlxSiO14, RE3Ta0. Also provided by the invention are tissue cultures of the wheat cultivar XY06-852 and the plants regenerated therefrom. The container has a depression, one end of which is opened, for receiving the ferrule therein. Each grip element has an outer shell, cover layer or casing which is at least partially transparent. The adhesive compound is disposed between the mirror and the facet such that the mirror is fixed to the facet under a compressive stress.