Manchester Memoirs, Vol. lix. (191 5), No. \% 55 



Sheet 22. 



Same formula as on sheet 21. 

 This representation of acetic acid first appeared in 

 1806, in Note-book ii., 262. It appeared also in 181 1 and 

 in 1823 ; other formulae were also used during this period. 



Sheet 23. 



On one side of this sheet are formulae for ether and 

 alcohol, which with modern symbols become 

 C 4 H 5 and G>H 3 0. They are inscribed : 



Ether, wt. 34. 



Oxy. 45-5 



Carb. 35 



Hyd»- i 9 '5 



100 



Alcohol, wt. 21. 



Oxy. 337 



Carb. 52 



Hyd n - 143 



j 00 



These formulae are evidently more recent than those 

 on sheet 5, where these compounds are represented as 

 C H and C 3 H respectively. Dalton considered quite a 

 number of different formulae for these compounds between 

 1805 an d 1810 ; they were mostly deduced from explosion 

 experiments with the vapours of these substances. It is 

 not until 18 19 that some formulae nearly like those of this 

 sheet are found in the note-books (Note-book vii., 447). 

 In lecture note-books dated 1824 and 1827 the molecular 

 compositions are recognised as equivalent to C 4 H r ,0 and 

 C,H O, and expressed as 



1 atom water and ./ atoms olcfiant gas, for ether, 

 and / atom water and 2 atoms olcfiant gas, for alcohol. 

 These formulae would have contained the same numbers 



