Contents xxxvii 



PAGE 



13. ON THE OXIDATION OF FERROUS SALTS. [From 



Proc. Roy. Soc. Edin. 1881, Vol. xi. p. 191] . . . 243 



This paper is a study in chemical dynamics and it 

 was suggested by my earlier work in that field, namely, 

 the investigation of the rate of decomposition of 

 Chloracetic Acid at 100 C. in the systems C 2 H 3 C1O 2 + 

 ,,,, H 2 O C t H 2 ClO 2 Na + 159 H 2 O and C 2 H 2 ClO 2 Na + 

 NaHO + 159 H,O. These investigations were made in 

 the Edinburgh University Laboratory in the year 1871 

 and were published in the Berichte of the German 

 Chemical Society (1871) iv. pp. 340, 863. 



It is of great importance, in the study of deep sea 

 muds, to determine both the ferrous and the ferric iron 

 present in them. The most convenient solvent of sub- 



tnces of this kind is moderately strong hydrochloric 

 acid, and the most convenient reagent for the estimation 

 of ferrous salt in a solution is Potassium Permanganate. 

 But, according to the orthodox canon, potassium 

 permanganate must not be used in hydrochloric acid 

 solution I was quite aware of the existence of the 



nnn. but I was not aware of any experimental evi- 

 dence which supported it. Accordingly, my first task 

 was, not to look up the history of the dogma, but to 

 find out for myself the circumstances under which the 

 presence of hydrochloric acid interferes with the 

 quantitative oxidising action of permanganate, and 

 how tin- disability is to be removed. The solution of 

 tins problem is given on page 244. 



Deta rous solutions used .... 



Other oxidising agents us-d besides IVrmar 

 namelv. < hlorate. I'CK hi. .rate and Nitrate ol 1 'tassmiii 244 

 Table 1 shows that, iisin- pi..per pierauti 

 ; d< >es not alle< t adveiselv t he . 



anganate ... 



Tal>l- II Action of (hlorate and IVrrhloiale of 



the ordinal \- " .<>m temperature . ] f> 



.! I I I I tiOfl bv (hi.. i. if ..! I'otas- 



.11) at room temp . r< >ndit ions the 



rate and the N ' -'47 



Tab!.- i\ Rate "i redm ti i hiorate 



tempera' 



on minutes . . M 8 



