2o6 Literary and Philosophical Society. 



inquiry on the force of vapour ; it is enough to say that 

 the tables stood the test of many years, and have been of 

 marvellous value to nearly three generations, besides stimu- 

 lating inquiry in many directions. 



Dalton might be wrong in fractions, but he was won- 

 derfully clear in his great ideas, and showed himself a 

 prophet and seer. It is strange how small are the facts 

 out of which he brings great results ; with him a new 

 science grows out of imperfect observations, and a new art 

 from a defect in his eyesight. 



As Dalton rises into power we approach his highest 

 work, the development and establishment of the atomic 

 theory, which first gave consistency to the long-discussed 

 ideas regarding matter, and practically showed that if 

 atoms did not form the basis of matter, it was clear that 

 matter acted as if it did consist of such bodies. In 1803 

 Dalton dared to give the relative weights of these atoms. 

 This is the great work of Dalton ; from that moment chemis- 

 try became a science, its leaves began to be legible, the 

 meaning of combination was to a great extent understood, 

 and weight, number, and measure were introduced as cer- 

 tainties into the conception of compounds. Transformations 

 were explainable, and the materia prima — the abstract — has 

 ceased to appear in books on the science. Lest any one 

 should mistake the meaning of this, it may be said that 

 there is no wish to deny the existence of a materia pri7na ; 

 on the contrary, we have held it from very early years to 

 be a sound thought. Dalton had evidently the idea, and 

 every chemist must hold it to be a probable source of our 

 elements. 



Before we attempt to give Dalton's position it may be 

 well to give a short account of the theories before him as 



