DISOXIDATION OF IRON BY HIDROGEN GAS. 373 



.particle was surrounded with hidrogen, gave up its oxigen^ 

 and formed vapour of water, which was perceived to con- 

 dense in the curved tube at the extremity of the barrel ; 

 and. which, at the close of the operation, when the heat 

 was excessive, traversed all the water in the tube and the 

 bottles, producing wreaths of white vapour, similar to 

 those issuing from rockets. 



Care was taken to keep in the tub a sufficient quantity 

 of water to cover the jar; and also such a quantity of gas 

 in the jar, that the pressure should be always nearly the 

 same, and the passage of the gas consequently uniform* 

 The fire was gradually increased ; but absorption still tak- 

 ing place, it was stopped when it appeared to be at a maxi- 

 mum. I then thought I observed, that the fire was not 

 stronger than might have been produced in a common fur- 

 nace, simply supplied with the current of air passing 

 through the ash. hole, so that the bellows were useless. This 

 however I mention only as a conjecture, more decisive 

 proofs being necessary to ascertain it. 



We were employed in the fatiguing operations of sup- 

 plying fuel, filling the jar with hidrogen, emptying under 

 it the bottles containing the hidrogen that had passed through 

 the apparatus, preparing others to receive that which was 

 constantly issuing from it, and keeping up the level of the 

 water in the two tubs, for four hours aud a half. At the 

 expiration of this time the iron oxides having absorbed the 

 eight bottles of hidrogen gas that had been prepared, it 

 was necessary to put an end to the experiment: and for ray 

 own satisfaction, I dilated the end of the gunbarrel that 

 contained the plate iron stem of the tube, and the curved 

 end of this stem enabled me to draw out the tube with ai) 

 iron wire. I weighed the iron immediately; that of Cogne Their weight 

 weighed 4*19 gr. [64-72 grs.] ; that of Elba, 3-77 gr- ^erTment^''" 

 [58-23 grs.] penmen , 



The oxidule of Cogne had become altogether stony, and which was pep* 

 of a yellowish gray. Many pieces of the oligist iron had pfjjg^^^*^^"** 

 lost their metallic lustre, having turned yellowish, and ac- 

 quired a duller lustre like that of silver: but I was notcer- 

 tain, that this iron was reduced, since no superfluous hi-r 

 ^rogen gas had passed over. 



3 " This 



