*One particular sample of "typical" Chephren building-block limestone was heated and vacuum-dried for several days, then vacuum-impregnated with water. The initial dry weight of the same (400 gm) increased by 7.6 percent (to 433 gm) after water impregnation. Left to stand in the laboratory several days at 55 percent humidity, the sample dried out to 404 gm. Measured density of the sample was 2.08, which is relatively low for limestone. This density measurement when applied to the Alvarez experiment leads to a better fit of the cosmic ray data than was possible earlier because a more common and greater limestone density was assumed.