48 Coward & Harden, Dai ton's Lecture Sheets. 



famous chapter " On chemical synthesis " in the " New 

 System," I., i, 211 — 216 (1808), is found the following rule 

 which led Dalton to choose the binary formulae for these 

 two compounds : " When only one combination of two 

 bodies can be obtained, it must be presumed to be a 

 binary one, unless some cause appear to the contrary." 

 No " cause to the contrary" was ever admitted by Dalton 

 for these formulae. 



Sheet 4. 



Plate VI. 



Alternative formulae for the oxides of carbon, 

 Dalton chose the latter two formulae to represent 

 carbonic oxide and carbonic acid. A discussion of this 

 question is found in the "New System," I., ii, 368 — 371. 



Sheet 5. 



Plate V. 



*' Atoms of Elastic Fluids." 



These are represented as surrounded by atmospheres 

 of heat of different sizes. They express Dalton's con- 

 ception, at one time, of the composition and size of the 

 atom of: 



1. Hydrogen. 



2. Hydrogen sulphide, 

 3 Nitrous oxide. 



4. Carbon dioxide. 



5. Water. 



6. Hydrochloric acid ("Muriatic acid"). 



7. Methane (" Carburetted hydrogen from stagnant water"). 



8. Carbon monoxide. 



9. Nitric oxide (" Nitrous gas "). 



10. Ammonia. 



11. Nitric acid. 



12. Alcohol. 



13. Oxygen. 



14. Nitrogen. 



15. Ether. 



16. Ethylene ("Olefiant gas "). 



