272 



and LaToisier, 



differed great- 



General con- 

 clusions. 



Red oxide. 



69 iron xo 31 

 oxigen, 



Reason! for 

 taking this 

 pioportion. 



ON THE OXIDES OF IRON. 



Lavoisier imagined, that the iron employed by Gayton 

 was not pure, because, in the experiments he made, he ob- 

 tained an increase of 45 to 100. 



The difference between the results of Guyton and Lavoi- 

 sier is too great to allow us to deduce from these experiments 

 the proportions of oxigen contained in the oxide. 



Conclusionfrom the experiments recited respecting thepropor* 

 tions of oxigen and iro7i contained in the different oxides. 



The numerous experiments on the oxidation of iron, that 

 have been mentioned, and which were made by persons ce- 

 lebrated equally for their talents, sagacity, and precision, 

 may be divided into two classes. The first, executed at a 

 time when the science was not sufficiently advanced, to in- 

 dicate all the causes that might influence the results, are not 

 sufficiently accurate for us to make use of them. The 

 second, made with the care and precision, that the present 

 state of the science admits, ought seemingly to enable us to 

 determine the proportions of oxigen and pure metal in the 

 oxides, if not accurately, at least with so near an approxima- 

 tion to the truth, thai we may employ them with advantage 

 in those chemical analyses in which iron is present. 



The proportion of oxigen in the led oxide of iron exhibits 

 some uncertainty. It was found to be 4(2 to 100 of iron by 

 Bucholz ; 44 by Mr. Gueniveau ; and 45 by Desrochcsand 

 myself. 



Several considerations lead me to adopt the proportion of 

 45 of oxigen to 100 of iron, supposing the three experi- 

 ments, which give these different proportions, to have been 

 made with the same degree of accuracy ; according to which 

 the composition of 100 parts of red oxide would be in round 

 numbers 69 iron, and 31 oxigen. 



Among the considerations that lead to the adoption of 

 this proportion, the following may be distinguished. 1st, 

 The method of oxidation by^lhe air assisted by heat, which 

 is the luost direct and simple. 2d, The difference between 

 the results of Bucholz and Gueniveau, 44 being nearer to 

 45 ihan to 42. 3d, The difference in specimens of iron. 

 Iron rendered impure, either by the union of carbon, by 

 oxidule remaining in it, or by scoriae, would receive a smaller 



addition 



