ON THE OXIDATION OF IRON. 



flammable. The succinic acid seems to approach nearer to 

 the nature of volatile oils, while the saccholaetic has more 

 analogy to the tartarous acid and sugar. 



The property observed in residuary coals by Proust, that, 

 when treated by nitric acid, they became soluble in fixed 

 alkalis, takes place also with the coal of saccholaetic acid. 



There is a difference between the coal of saccholaetic 

 acid, aud that which is produced by the sublimed acid : the 

 first yields lime on incineration ; the second, potash. 



147 



XII. 



Letter from Mr. Hassenfratz, Chief Engineer and Pro- 

 fessor of Mincralurgy at t/te Practical School of Alining, 

 to Mr. JSerthollet, on the Oxidation of Iron*, 



I 



HAVE long been of opinion, that oxigen combines Oxigen sup- 



with iron in various proportions. The experiments of P? scd to c ? m * 

 Proust f, by which he shows, that only two precipitates are indifferent™" 

 formed in all the solutions of iron, one of green oxide and proportions, 

 the other of red, made me waver in my opinion, and I was b y p r o USt . 

 on the point of giving it up ; but, on comparing the quan- 

 tity of oxigen mentioned by Proust as combined with iron 

 with the quantities deduced from experiments made by 

 other chemists, who enjoy -a well des< >ved reputation, 1 

 found such differences in the proportions, that I resolved to 

 suspend my judgment till fresh facts should confirm or re- 

 fute this doctrine. 



In fact Proust says, that the green oxide is composed of Different pro- 



28 parts of oxigen to 100 of iron, and the red oxide of 48 P ortk ' ns as * 



. _, . .. . . signed to the 



of oxigen. 1 he experiments or Lavoisier, those which you oxigen. 



uudertook in conjunction with Messrs. Monge and Vander- ,9n$% 



monde, those of Vauquelin, and lastly those of Bucholz J, 



prove, that iron oxided at a minimum contains 30 of oxigen 



to 100 of iron. As to the red oxide, chemists are not 



* Annales de Chimie, vol. LXVII, p. 309. 



t Memoir read to the Institute in the year 5. r • • 



% Annates de Chimie, vol. LXV, p, 202 j or Journal, vol. XXV, 

 p 333. 



L 2 vet 



