civ. PRESIDENT'S ADDRESS. 



going on as to the production from it of helium. There is now 

 evidence of the production of radium from actinium, the actinium 

 itself being a product of uranium. Numerous experiments show 

 that the radio-active power of various substances is not altered 

 by an alteration of temperature, even in the wide limits between 

 i 80 degs. and 1,600 degs. Centigrade. The absorption of the 

 radium emanation by charcoal is another interesting discovery, 

 and the heating effect on the earth of the radium contained in 

 its rocks is a subject for divers opinions and much speculation. 

 Platinum is a metal which is much in demand, and has become 

 of late years scarce and valuable, being now considerably dearer 

 than gold. The uses of aluminium, one of the most generally 

 distributed and common metals in combination, have been 

 greatly developed, the latest being due to experiments on alloys 

 of a small proportion of aluminium with a large proportion of 

 copper. These alloys are practically incorrodible by sea water, 

 whilst some of them, containing from 10 to 15 per cent, of 

 aluminium, are equal even to steel in hardness and other desir- 

 able qualities, and in some respects superior, and have no doubt 

 a great future before them. One of the great difficulties about 

 aluminium is to produce a satisfactory joint by soldering, a 

 difficulty which has as yet, I believe, been only very partially 

 overcome. A high vacuum can now be obtained through the 

 discovery that the residual gases (except those of the argon 

 group) are absorbed by heated calcium. The air in the receiver 

 is first replaced by some gas which does not contain argon ; the 

 receiver is then emptied by a pump, after which the calcium 

 is electrically heated and absorbs the residue, forming an 

 extremely perfect vacuum. Experiments seem to show that 

 Xenon, which had been ranked as an elementary substance, is a 

 mixture of various gases. It has always been thought that the 

 rusting of iron was caused by contact with oxygen and water, 

 but it has apparently been proved that if all the carbon dioxide 

 can be eliminated from the water before the iron is placed in it, 

 no rusting at all will take place. My notes on the chemistry of 

 the past year may fitly close with a mention of the International 



