338 On defiulie Proportions. 



oxide, containing 63'78 of rnetallic iron. Now, 100 parts 

 ot sulphuric acid require, in the base by which they are sa- 

 turated, 20-29 of oxygen, and 68-78 :' 20-29= 100 : 29-5 j 

 a result which agrees very accurately with Bucholz's ex- 

 periments. 



i exposed ten grammes of crystallized sulphate of the 

 protoxide of iron, in a retort, to a heat which was kept be- 

 low ignition, in order to drive off the water of crystalliza- 

 tion : they lost 4-63 gr. They were then kept in a state 

 of ignition, until ihe acid was completely expelled, and they 

 afforded 2*82 gr. of red oxide ; which ]\&<\ consequently 

 been combined with 2'8'12 ar. of sulphuric acid, and which 

 contain \'{)5 gr. of iron. The acid, the iron and the water 

 amount together to 9*422 gr. The remaining •.'>78 must 

 have been ihe oxygen of the protoxide; and \QS -578 = 

 100 : 29-6; so that 100 parts of iron were united to 29"Q 

 of oxygen. 



Since in the dry sulphate of the protoxide of iron 100 

 parts of sulphuric acid are combined witli 68'78 of iron, 

 and the oxygen necessary for its oxidation, this oxygen must 

 either be 29 3, according to the foregoing calculation, or 

 22 i 25, half of that which is contained in the red o.xide, for 

 300 parts of iron. It is easy to show that the latter suppo- 

 sition leads to consequences which do not agree with the 

 experiments ; and the former being supported by two dif- 

 ferent modes of calculation, we mav consider it as suiEcienily 

 established that the protoxide of iron consists of 

 Jron .... l~ri<2 1000 



Oxygen , 22'78 29'5 



The truth of this assertion may be thus demonstrated. 

 If we burn the sulphate of the protoxide in a properly re- 

 gulated temperature, the protoxide becomes converted into 

 an oxide at the exjiense of the acid, a part of which is de- 

 composed, while another part passes over undecomposed, 

 or remains behind, according 10 the degree of heat em- 

 ployed : the salt containing, for 100 parts of sulphuric acid, 

 84 or S9 07 of the protoxide, and requiring for its complete 

 oxidation in the first case I5'22 parts of oxygen, in the se- 

 cond 10-13. Since in this process the sulphuric acid is 

 only reduced to the sulphurous, 13*22 parts of oxygen 

 would imply that three-fourths of the sulphuric acid, or 

 76 1^ parts, but 10-13, that half only was decomposed, and in 

 the latter case we should be able to obtain from the salt oxi- 

 da'ed by ignition more than one-fourth of the sulphuric 

 acid unaltered. In order to determine between these alter- 

 xiativeSj I toojc a portion of sulphate of the protoxide, cry- 

 stallized 



