PRESIDENT'S ADDRESS. Ixxiii. 



established ideas and beliefs in this branch of science that 

 even the foundations on which it rests have been disturbed, 

 and we cannot now talk of atoms as if they were certainly 

 indivisible and constant for each elementary substance, as 

 we have numerous cases of what would have been looked 

 upon as an element turning gradually into some other 

 substance. The old alchy mists have been ridiculed for a 

 similar belief, but the day may not be far distant when some 

 commoner substance may be transmuted into gold, as 

 uranium is believed to be finally changed into lead, though 

 further evidence is still wanting. Lately both neon and 

 helium have appeared in vacuum tubes under the influence 

 of X-rays in such a manner as to suggest that they have 

 been transmuted into these elements from other substances, 

 but the cause of their appearance does not yet seem quite clear. 

 Thirty-four radio-active substances are now known, 14 of 

 which have been discovered as such in the last seven years. 

 From calculations which have been made in regard to the 

 heating power of the radium found in rocks, it would appear 

 that the earth ought to be becoming gradually hotter, instead 

 of cooling down, as all geological evidence leads us to believe. 

 This shews either that there are other as yet undiscovered 

 forces at work acting in the other direction, or that there is 

 some flaw in our facts or deductions. There is some reason 

 to believe that radium exists in the chromosphere of the sun, 

 but the spectroscopic indications are somewhat uncertain. 

 On plants radio-active water causes a prompt germination 

 and rapid development up to a certain strength, but beyond 

 this it is harmful. Leaving for the present this very fertile 

 subject of radium, I come to an investigation which will 

 interest more the Antiquarian Members of our Club, namely, 

 the pigments used by the ancients in illuminated MSS. from 

 the 7th to the 15th Century. These include vermilion, red 

 lead, orpiment, ultramarine, azurite, malachite, verdigris, 

 lakes, a Tyrian purple, and an undetermined copper green. 

 These results are being published in detail by the Society of 

 Antiquaries, and may be sometimes useful in helping to fix 



