396 APPENDICES 



the oxygen, become evident or kinetic in the heat of the 

 flame. And exactly as there is a definite unalterable relation 

 in weight between the carbon and hydrogen of the wax and 

 the products of their combustion, carbonic acid and water, so 

 there is a definite and unalterable relation between the 

 amount of chemical potential energy of the constituents of 

 the wax and that of the heat evolved by their oxidation. 

 Both these relations can be expressed by numbers, and these 

 numbers are the foundation constants of Science. By the 

 determination of the combining weights of the elements and 

 their compounds Dalton made clear the truth of the first 

 principle ; by rigorous experiments Joule that of the second 

 by determining the mechanical equivalent of heat, namely, that 

 a weight of 772 Ibs. falling through the space of one foot 

 develops a definite and unalterable amount of heat capable of 

 raising the temperature of one pound of water from 32 to 33 

 Fahrenheit. 



You all know something about chemistry, of what it has 

 done for the world, how far-reaching it is, how wonderful 

 scents are prepared by the skill of the chemist from evil- 

 smelling tar ; how, even, a substance 300 times sweeter 

 than sugar has been manufactured artificially from the same 

 material that the chemist can even do more than the busy 

 bee, for he can manufacture honey from its constituents, 

 whereas the bee can only sip it ready-made in the flower. 

 There seems to be only one limit to the synthetic power of 

 the chemist. He looks forward to the possibility of manu- 

 facturing all crystalline and liquid bodies, the one goal which 

 at present, it appears, he cannot reach is the artificial 

 construction of organised matter, the starch granule, or the 

 blood corpuscle. 



My object this evening is to endeavour to point out to you 

 some of the origins of these great things ; to indicate to you 

 the principles without which all this progress would have 

 been impossible, and at the same time to tell you of 

 the interesting personal history and characteristics of the 

 man who did more to lay these foundations than any other. 

 Before John Dalton's time, and without his Atomic Theory, 

 chemistry, as an exact science, can scarcely be said to have 

 existed. It is true that many facts were ascertained, but the 

 relation between these facts was not made out. A chemist 

 before Dalton's time might be aware of the kind of action 

 which takes place when two chemical substances are brought 

 together, but no one could calculate with precision how much 

 of each ingredient was required to build up the new body, 



