ELISHA MITCHELL SCIENTIFIC SOCIETY. 29 



and it is only a question of cost that interferes with its 

 present use. The second constituent, carbon monoxide, 

 can be prepared by the same ag-enc}^ from the carbon 

 dioxide or carbonic acid, of which we have been speak- 

 ing- and, if the demand justified it, the methods of pro- 

 duction for both of these substances could doubtless be 

 so improved and cheapened as to become entirel}^ prac- 

 ticable. 



We must bear in mind that there is no destruction of 

 matter possible on the face of the g-lobe, and our use of 

 the coal means onl}^ that we change it into some not 

 immediately useful form from which, as we have just 

 seen, it is possible to recover it, thus brino-ing it into 

 use ag-ain. In this we would be but imitating" nature 

 in her C3xle of chang^es. Man dies, his bod}^ deca3^s 

 and its constituent materials come into g^eneral circula- 

 tion once more and are ready to be utilized in the build- 

 ing- up of a new man. Men burn a plant, some living 

 g-rowing plant somewhere gathers together the mate- 

 rials thus once used and scattered, and gets them into a 

 shape in which man can use them again. 



We have not taken into account the possibilit5% as 

 shown by repeated experiments, of utilizing the sun's 

 heat and the immense amount of energy scattered by 

 it over the earth's surface. We are told that the total 

 amount of this energy poured out every 3^ear upon each 

 acre of the earth's surface is some 800,000 horse-power. 

 As Crookes says, what a waste is here ! A flourishing 

 crop grown upon that acre utilizes only some 3,200 

 horse-power and consequently 786,800 horse-power is 

 lost. 



Even a small part of this caught, concentrated, set 

 to work, changed into electricity or stored up against 

 a rainy day when clouds come between us and our 



