ON THE OXIDES OF IRON. 



£'67 



that he obtained more or less gas, according to the tempera- 

 ture at which the experiment was made. From some expe- 

 iiinents he inferred, tliat the proportion of oxigen combined 

 with 100 parts of iron must be 32. In one experiment, 

 made between 25- and 30° of R. [88° and lOO** F.], 32*27 

 offtxigen combined with 100 of iron*. Notwithstanding 

 these differences, he conceived the quantity of oxigen com- 

 bined with iron dissolved in nitric acid could be carried only 

 to 29 per cent of iron. 



It is difficult to efitiioate by this method the proportion of objections to 

 oxigen in a constant state of the oxide, because, 1st, the ^his method, 

 proportions of gas obtaine<l vary with the temperature and 

 the degree of concentration of the acid ; 2dly, it is ex- 

 tremely difficult to obtain a uniform nitrous gas; 3dly, the 

 iron IS always oxided in different degrees. 



Bergman f, having dissolved separately more than Bergman vtith 

 forty varieties of iron in sulphuric acid diluted with water, sulphuric and 

 and in hiuriatic acid, obtained with the former from 

 36 to 52 Swedisli cubic inches of hidrogen from the doci» 

 liiastic centner of iron, and with the latter from 15 to 51 

 inches. 



Guj'ton quotes an experiment of Priestley, in which the rriestley. 

 English philosopher obtained 155*5 cubic inches of hidrogen 

 gus with 27*55 [grs.] of iron; which would carry the quantity 

 of oxigen combined as fur as 39 7 parts to 100 of ironlj, 



Lavoisier, haviiig dissolved 100 grs. of iron in dilute sul- Lavoisier, 

 phuric acid, obtained 110 cubic inches of hidrogen gas, 

 which would make the quantity of oxigen combined with 

 100 of iron 27*3. 



Vandermonde, BerthoUet, and Monge, dissolved 21 vari- Vandermon- 

 eties ot" iron in sulphuric acid diluted with water. From the ^^^J Monre^ * 

 purest iron they obtained 78 ounce measures of hidrogen 

 gas, at the temperature of 12° R. [59** F,], and pressure 



• lb. p. 497. t Analysis of Iron. 



II Not being able to turn to the passage in Priestley, as the reference is 

 to the EncycIop6ciie, I car.not verify the numbers here given. Mr. 

 Has>enfratz appears to have taken the numbers as representing Fiench 

 cubic inches, and French grains j but supposing them to be English 

 inches and grains, whicli ib tery probably the case, the proportions will 

 no give more then 2/09 oxigen to 100 iron. C. 



^8 iu. 



