222 



appeared unchanged, whilst in the case of the iron, they had 

 a dark blue-black appearance, owing to the formation of 

 gallate and tannate of iron. 



In order to ascertain the comparative action of soft and 

 salt water upon iron and galvanized iron when in contact 

 with oak under identical circumstances, he made the following 

 series of experiments. 



Plates of galvanized iron having 18 inches of surface lost 

 during three months the following weights: — 



SOFT WATER. SEA WATER. 



Plate No. 1 . . . . 0.10 grains. 



„ No. 2.... 0.11 „ 



„ No. 3 0.095 grains. 



„ No. 4 0.090 „ 



Similar plates of iron lost during the same time : — 



SOFT WATER. SEA WATER. 



Plate No. 1 1.28 grains. 



No. 2.... 1.52 „ 



99 



„ No. 3 2.40 grains. 



„ No. 4 2.38 „ 



There can therefore be no doubt that galvanized iron offers 

 great advantages, the action of water on it being less than a 

 tenth of the same action on ordinary iron. As there is no 

 doubt that iron when galvanized is in the most favourable 

 electrical condition to resist the action of oxygen, being in 

 an electro-negative condition, it follows that in all probability 

 the use of galvanized iron would be very advantageous in 

 armour-plated and other iron ships. The Author hoped 

 that Government and other large ship builders would avail 

 themselves of this suggestion, and make experiments on a 

 large scale to verify the results he had obtained. 



