Manchester Memoirs, Vol. lix. (191 5), No. 12. 61 



The same formulation is found in Laboratory Note- 

 book iv., 57 ( 1 8 1 1 ), with Gay Lussac's figures for com- 

 parison. 



Chemical Reactions represented by Formula. 

 Sheet 34. 

 Plate VII. 



Reduction of a mercuric salt to a mercurous salt. 

 Above the line is represented a mercuric salt ("A" is 

 frequently used in the note-books to designate generically 

 an acid). Below the line are represented two molecules 

 of the corresponding mercurous salt formed from the 

 mercuric compound by interaction with an atom of 

 mercury. 



This sheet may well have been prepared to illustrate 

 the Edinburgh and Glasgow lectures of 1807, in the notes 

 for which appears the following : 



" Muriat Mercury 1 A+i protoxide M (black) 



Oxymuriat M \ A deutojdd M ( d) 

 or Corros. subl. J x ' 



hence the reason why crude Merc. & cor. sub. 



produce calomel or muriate of M." 



Sheet 35. 

 Plate VII. . 



The combustion of methane. Represented by the 

 formula for methane above the line, and below the line 

 formulae for one molecule of carbonic acid and two mole- 

 cules of water. 



These two diagrams are almost chemical equations. 

 Dalton has not employed equations to any great extent ; 

 one of the earliest is in the first laboratory note-book, 

 page 278, August, 1804, and is reproduced in Roscoe and 

 Harden's " New View of the Origin of Dalton's Atomic 

 Theory," p. 63. 



