338 On the Construction of Kitchen 



substances cannot communicate oxygen to iron (with 

 which that metal must unite in order that rust may 

 be formed), and as they prevent the approach of other 

 substances which could furnish it (air, water, acids, etc.) 

 as long as the surface of the iron is completely covered 

 by them, it is evident that no rust can be formed. But 

 boiling-hot water, and more especially water heated and 

 actually made to boil in such a vessel, could not fail to 

 dislodge the fat from the surface of the metal, and leave 

 it naked and exposed to every thing that is capable of 

 corroding it. 



Kitchen utensils made of iron may be tinned on the 

 inside to preserve them from rust ; and this is frequently 

 done. But even tin, though it be much less liable to be 

 dissolved by those substances which are used in cookery 

 than iron or copper, yet it is sometimes sensibly corroded 

 by them, and consequently is taken into the stomach 

 with our food. 



What its effects may be on the human body, when 

 taken in very small quantities, I cannot pretend to 

 determine. In large doses it is well known to be a 

 fatal poison. 



That the tin with which the insides of kitchen boilers 

 and stewpans are covered is actually corroded in many 

 of the processes of cookery is rendered highly probable 

 by the very short time that such a coating lasts, when 

 the utensil is in daily use ; but I had, not long since, 

 a still more striking proof of that fact Learning by 

 accident, from my cook, that a dish of which I am very 

 fond (stewed pears, which I frequently eat with bread 

 and milk for my supper), required three hours' boiling, 

 it occurred to me that, as this process was performed in 

 a copper stewpan tinned, and as it lasted so long a time, 



