Substance I II III IV
Platinum 1·167 Mercury ·726 ·661 ·538 ·493 Lead ·641 ·563 ·480 ·440 Zinc ·282 ·266 ·248 ·266 Aluminium ·104 ·104 ·104 ·104 Glass ·087 ·087 ·087 ·087 Water ·034 ·034 ·034 ·034
In the above table, the absorption in aluminium, glass and water was too small to determine with accuracy the variation of λ with distance traversed. It will be observed that, for the denser substances, the coefficient of absorption decreases with the distance through which the rays have passed. This indicates that the rays are heterogeneous. The variation of λ is more marked in heavy substances.
Table B gives the values of λ divided by density for the above numbers. If the absorption were directly proportional to the density, the quotient would be the same in all cases.
