THE ACTION OF SEA-WATER UPON CAST-IRON, _ 153 
Mallet found that the approximate depth of corrosion fi clear 
the low: 
sea-water at end of one century would be as follow: 
Welsh cast-iron. Hot and cold blast Gril ol 300 i inch. 
Trish Cold ‘306 _,, 
Mixed cast irons; sen arid Welsh, Trish and } 
Wel uty nl 
Scotch eabit0N. Chiefly hot blast. . 879 4, 
Staffordshire, Shropshire, and Gloucestershire ) 385 
cast-iron. Hot and cold blasts % 
rey cast-iron, mixed. Skin removed by olanin “S59. 5 
Derbyshire and Yorkshire cast-iron. Hotandcold -431_ 
Wrought-iron. Standard bar, No. 2 Dowlais ... 543 , 
In another table + he gives the approximate depth of corrosion 
for the following wrought-irons and steels at the end of one cen- 
tury in clear sea-water, foul sea-water, in ag Ciesla and 
when freely exposed s the weather in Dublin 
Exposed to 
1 sea- | Clear fresh- 
parece iret water. - com 
Red short bar, Staffordshire..| -276 inch. | -644 inch. | 032 inch. | °335 inch, 
Common bar, Shropsh he a Sel =. “484 5, 081"; 540, 
Best bar, Staffordshire......... 316 4, | 423 ,, 039 ,, 361 4, 
Best Welsh bar, Dowlais...... 278 ,, | 638 » | 353 4, 
Low Moor boil ia es “S15. 35 ‘ 035, 332 4 
mmon boiler plate ......... ‘Sing tt DON 1 ee on | ee 
Swedish bar, Danemora o77 | 96 7 1-080 |, || “470° =, 
agote p ectepeeel “ORK 6b BIO tp ORK ay 24 209 ow 
Blister steel bar, soft... | -298 of SR | DIG yy | WL sw 
Sheer steel bar, POG seces 313 ” 676 ” 025 2” 389 » 
Cast s tilted bar, soft 441 ” 559 ” 026 ” ” 
eae 5; ” ” 156 
sciia, t e 
As in the former table the results were obtained from speci- 
mens which had been immersed for 732 days. 
Mallet found that the corrosion of cast-iron, which has had its 
re one, when the coat of plumbago and rust 
cat is removed prior to a second immersion. When the 
and less porous, thus to a greater or less extent it mechani- 
cally defends from co TTOSsion. 
oo 
+ Pitish Association Re 
ports, 1840, vol. at 299, 
Brit. Association Reports, vol. xiii, 1843, p. 53. 
