Postcard image of uniformed soldiers standing in a curving line, with handwritten text in the lower-left corner: "The Mess Line. Camp MacArthur. Waco, Texas." Rows of large tents are visible to the left of the line and mess hall. Handwritten text addressed to Miss Ethel Reser and postmarked 1918 says: "Are you taking good care of the dogs? How's your lazy dad? This is how your uncle gets his eats. Al"

From Introduction: "The investigations presented in this bulletin have been undertaken by the bureau with a view to a better understanding of the conditions which confront the producer of commercial feldspar and also with the object of determining wherein the various deposits of feldspar differ."