Manchester Memoirs, Vol. lix. (191 5), No. 12. 51 



Sheet 6. 



Plate VI 



Formula, inscribed " Nitrous oxide, 13'cj." 

 The atomic weights used were N=4'2, = 5*5. A 

 reference to Table I. shows that these are later than 

 September, 1803, an ^ earlier than August, 1806. They 

 actually appear in 1804 an d 1805. The diagram is there- 

 fore of earlier date than the older of the atomic weight 

 lists. 



Sheet 7. 



Plate VI. 



Formula, inscribed "Carbonic acid, 15*3." 

 The atomic weights used were C = 4"3, = 55. These 

 belong to the same period as the atomic weights of the 

 previous formula. 



Sheet 8. 



A similar formula for carbonic acid. 



Sheet 9. 



Plate VI 



Formula, inscribed " Carburetted hydrogen from' 

 stag, water, 63." 

 This again requires C = 43 and is therefore of the 

 same period as the formulae for nitrous oxide and car- 

 bonic acid. 



Sheet 10. 



Plate VI 



Same formula as above for methane, together 

 with a diagram apparently representing 3 

 atoms of hydrogen around a carbon atom. 



The exact use Dalton made of this sheet is not clear. 



