In the appendix to the paper on the new mineral, baddeleyite, in the last number of the Magazine, Mr. Fletcher proves the identity of that mineral with the brazilite of Husssk, and explains the deviation in specific gravity and the original incorrect determination of the chemical composition of the Brazilian mineral by the supposition that the crystallographic measurements were made on the true mineral, while the specific gravity determination and chemical analysis were made on another, a tantalo-niobate of yttrium associated with it.