48 Van Beek on the Supposed Property of Tin 



8. A plate of tin, 65™ *" square, on which was fixed a small 

 piece of iron plate of 23'" "" square, being in the same manner 

 exposed to the action of sea-water, the iron was in a very short 

 time oxidated, whilst the tin remained perfectly bright, with- 

 out any trace of oxide of tin in the A'essel. The quantity of 

 oxide derived from this small piece of iron, was more than the 

 double of that produced in the same time from the much larger 

 iron plate of the first experiment. 



4. By exposing a perfectly similar combination of tin and 

 iron to the action of sea-water, the immediate contact of the two 

 metals being only prevented by a thin plate of mica placed be- 

 tween both ; in eight days the iron was but slightly oxidat- 

 ed, whilst the oxidation of the tin plate was evident. 



5. A similar combination of tin, mica, and iron (but by which 

 the two metals were brought in conjunction by a thin platina 

 wire round the mica), being exposed in sea-water, the iron was 

 again soon oxidated, though, as it seemed, in a smaller degree 

 than that of the third experiment. In eight days, there was 

 already much oxide of iron deposited on the sides and the bot- 

 tom of the glass, whilst the tin did not shew any oxidation. 



6. A plate of tin, in the same manner placed in sea-water, 

 very soon produced traces of oxidation, principally on the up- 

 per side of the plate, which was placed obliquely against the 

 .-ades of the glass-vessel ; and the oxidation was chiefly perceived 

 on the points where the surface of the tin-plate shewed some 

 irregularities. The quantity of oxide obtained in this manner 

 ill forty-two days, was but small compared to the quantity of 

 the oxide of iron of the preceding experiments. 



7. A plate of iron, as in the first experiment, on whose surface 

 was fixed a small piece of zinc-plate, on exposure to sea-water, 

 remained constantly bright at the expense of the zinc, which 

 uas strongly oxidated. 



The results of these experiments are in perfect accordance 

 with those former'y obtained. The 2d experiment shewed that 

 iron which, when exposed alone to sea-water, is speedily and 

 strongly corroded, was by no means preserved from oxidation by 

 tin ; whilst by the 3d experiment it is proved that, on the con- 

 trary, tin which, when exposed alone to sea-water, as was shewn 

 bv the 6th experiment, is easily corroded, was preserved from 



