658 SCIENCE PROGRESS 



reduced to metal by " pure hydrogen " — whether ordinary pure 

 or chemically pure we are not told. 



Iron so prepared was not visibly oxidised under the conditions 

 arranged by Lambert and Thomson even after several months. 



On the other hand, iron made in precisely the same way from 

 " ordinary pure iron " invariably showed signs of oxidation in 

 two or three hours. In like manner, when platinum vessels 

 were used, particularly when a platinum boat was substituted 

 for one made of iridium to contain the iron oxide (prepared from 

 the most purified materials) while it was submitted to reduction 

 in hydrogen, the iron produced underwent oxidation readily in 

 two or three hours, rusting taking place invariably at those 

 parts of the metal which had been heated in contact with the 

 platinum tube. All kinds of commercial iron rusted readily 

 in their apparatus ; they even go so far as to state that com- 

 mercial electrolytic sheet iron cleaned by Moody's method with 

 chromic acid was readily attacked, thus disposing again of the 

 contention that chromic acid necessarily renders iron passive.^ 



It is clear that Lambert and Thomson unwittingly arranged 

 matters so that iron would rust in their apparatus whenever it 

 was coupled with the necessary electro-negative conductor ; by using 

 iridium vessels, which apparently are not in the least subject 

 to attack even by chlorine and strong acids, they were able 

 to prepare an iron free from electro-negative impurity — as is 

 to be expected on all grounds, such iron did not rust. This 

 result is an interesting verification of the only theory of chemical 

 change that is in accordance with present knowledge but it 

 is nothing more. The work affords no disproof of Moody's 

 argument ; on the contrary, it supports it most strongly. There 

 can be little doubt that although Lambert and Thomson were 

 successful in carrying the purification of iron very far, they 

 were not sufficiently careful to secure the removal of carbon 

 dioxide from their apparatus. In view of the results obtained 

 by others, it is inconceivable that they would have arrived at 

 results such as they describe had they done so. And it is 

 not difficult to see where they went astray. Whilst they took 

 great care to prepare oxygen free from acid impurity by 

 electrolysing a solution of baryta and all water introduced into 

 the apparatus was carefully distilled from an alkaline solution, 

 they evidently were not alive to the difficulty of removing 



' Compare Brereton Baker, Chemical Society'' s Report, 1910, p. 38. 



