Manchester Memoirs, Vol. lix. (191 5), No. 12. 47 



Sheet. 



5 



14 



5 6 — 6 3 

 167 



56 

 2SP-57? 

 25 ? 3 2? 39? 46? 



Not represented. 



Symbol only, 

 no weight. 



" New System," II. 

 Azote 5±,orio? 



Sulphur 13, or 14 



Gold 60 + 



Mercury... ... 167, or 84? 



Copper 56, or 28? 



Tellurium ... 29, or 58? 



Chromium ... 32 



Calcium 17? 



Strontium ... 39 



Barium ... 61 



^ . ( Neither name 



Osmium ... < • , , 



( nor weight. 



It appears that the doubts entertained about the atomic 

 weights of azote, sulphur, mercury and copper, at the time 

 of compilation of the " New System," did not exist when 

 the sheet was compiled ; but on the other hand that the 

 reverse is the case for chromium. The comparison of 

 these figures therefore gives no clue as to which of the 

 two lists is the earlier. It seems probable however that 

 the sheet was made earlier than 1827, since calcium, 

 strontium and barium find their place as elements in the 

 book. The only apparent indication to the contrary is 

 the presence of the element osmium on the sheet and not 

 in the list in the book ; but Dalton was quite aware of the 

 existence of this element long before 1827, for an account 

 of it appears in the " New System," I., p. 255. The reason 

 that it did not appear in the list of elements in the book is 

 that Dalton had no data for determining its atomic weight. 



Sheet 3. 



Plate VI. 



Alternative formulae for (a) water, (b) ammonia. 



In the Edinburgh and Glasgow lecture notes (1807) 



Dalton refers to this or a similar diagram immediately 



after a discussion of the composition of water and 



ammonia: " See small scheme of three modes." In the 



