1907.] on Prohlems of Applied Gliemistry. 567 



which exist iu the earth's crust, and which have preserved to us a tiny 

 portion of the solar energy radiated upon our planet during that 

 period, millions of years ago. At that period, for various reasons, 

 the production of living matter must have been incomparably more 

 rapid than is the case at present. During untold ages this stored-up 

 energy was lying idle, hidden under the accumulations of the more 

 recent geological formations, not merely up to the advent of man, but 

 through nearly the whole of his history. Leaving aside the tens of 

 thousands or (according to some) hundreds of thousands of years 

 during wh(ich man existed before the dawn of history, we must 

 remember that historical documents exist in Egypt, Babylon, India, 

 and elsewhere, taking us back at least 8000 years, and that the most 

 glorious times of Greek and Roman civilisation are about 2000 years 

 behind us. How modern, in view of these figures, is the use of the coal, 

 and over what a short time it will extend ! In these isles the use of 

 coal is much older than in any other country, Ijut even here its serious 

 exploitation is comparatively recent, dating Ijarely 150 years back ; 

 whilst its future (even if we disregard the more pessimistic estimates) 

 is not likely to exceed some 200, or at most, 300 years. Germany 

 and the United States will probably hold out 200 or 300 years longer, 

 but in all other countries the chances are all the other way. 



Well, what is to happen then ? Those countries where water 

 power is abundant may possibly substitute electrical heating for that 

 produced by the burning of coal, but what about England and 

 Germany, which are so poorly off in that respect ? Even in those 

 countries which are more favoured, the amount of water power is by 

 no means infinite ; and, if it had to Ije drawn upon, not merely for 

 motive purposes, but for the production of electricity for heating 

 purposes, it would be found insufficient in most places. Here we are 

 faced by one of the greatest problems of applied science, both in 

 chemistry and in physics, a problem which will give plenty of occupa- 

 tion to generations of future inventors. At present we can only 

 surmise that some solution will present itself in the shape of a direct 

 conversion of the sun's rays into other forms of energy ; but the 

 means by which this would be practically accomplished are at present 

 quite uncertain. 



The Age of Coal, in the midst of which we are living, short as it is 

 evidently doomed to be in the long history of mankind, has been of 

 incalculable service. For our purposes we may dismiss the earlier 

 part of it, and look back only a hundred years. In all branches of 

 industry, in locomotion, in the means of communication, and in 

 innumerable matters ministering to the comforts of life, the progress 

 since that time has been going on at a geometrical ratio. The 

 present state of all these factors of civilisation in Europe (to say 

 nothing of America) differs from that obtaining a hundred years ago 

 far more than the latter differed from the Roman era, or even from 

 the age of the Egyptian kings. And this miracle has been brought 



