58 Coward & Harden, Dal tons Lecture Sheets. 



to the period 1810 to 181 5. The formulae for acetic acid 

 and oxalic acid occur frequently during many years, 

 together with some others suggested but soon discarded. 



Sheet 25. 



Oxalic acid, again represented by symbols equivalent 

 to C0O3. On the back : " 2 atoms with 90 asunder both 

 oxygen and charcoal." " 1 atom oxygen with 1 hole." 



Sheet 26. 



Citric acid, represented as CHO. On the back : 

 * l 6o° asunder." This formulation has been found in the 

 laboratory notes of 1 841, and at the end of the pamphlet 

 "A New and Easy Method of Analysing Sugar," a product 

 of Dalton's last years, date about 1840. 



Sheet 27. 



" Acetic acid " erased. 



" 5 carbone 37 

 4 wat. 48." 



Formula representing this acid by a central carbon 

 atom with four " vegetable atoms " symmetrically disposed 

 around it. This formulation for acetic acid is described 

 at the end of the pamphlet, " A New and Easy Method 

 of Analysing Sugar." 



Sheet 28. 



" Tartaric acid," erased, and replaced by " acetic acid." 

 Formula representing a central carbon atom with five 



"vegetable atoms" symmetrically disposed around it. 



On the back : 



^— =72° asunder." 

 5 



" each peg .... rest is obvious." 

 Tartaric acid is represented in the pamphlet mentioned 



