1885.] A. Pedler — Corrosion of lead in Tea-Chests. 139 



full in the Journal, Part I. The conclusions arrived at by Mr. Pedler 

 may, however, be stated here. They are : 



1. That tea properly manufactured in the ordinary way has no 

 power to corrode lead. 2. That if unseasoned and damp wood is used 

 for the manufacture of tea boxes, corrosion of the tea lead is, under 

 favourable circumstances, almost certain, but that some varieties of 

 wood will act more violently than the others. 3. That even if seasoned 

 wood be used, and if it be allowed to become saturated with water and 

 then placed in favourable circumstances of heat and moisture, corrosion 

 of the tea lead may occur, though not to so great an extent as if un- 

 seasoned wood had been used. 4. That the active agent does not exist 

 ready formed in unseasoned wood, but is produced by a secondary action 

 from the constituents of the wood. 5. That the corrosion is not due 

 to contact action between the lead and the wood, but that a volatile 

 substance is gradually produced from the unseasoned wood. 6. That 

 the corroding agent is usually acetic acid in the presence of moist air 

 and carbonic acid, but that other acids of the same series are sometimes 

 produced and also act on the lead, and in the case of butyric and 

 valeric acids, a greenish yellow incrustation is formed differing entirely 

 from the whitish and yellowish white incrustation produced from the 

 acetic acid. 7. That the acetic and other acids are produced by the 

 decomposition (probably by a kind of fermentation under the influence 

 of heat and moisture and perhaps induced by some of the unstable nitro- 

 genous compounds present) of certain substances which are known to 

 be present in wood. Such bodies are fermentable sugars, starchy 

 matters, malic acid, &c. 8. That the lead linings of the tea chests 

 having been corroded and perforated by the corroding of the acids in 

 the presence of moist air and carbonic acid, the tea can easily take up 

 the disagreeable odour which the wood itself will possess after it has 

 undergone the change in which acetic and butyric acid &c. are formed 

 and thus the quality of the tea will be deteriorated. 



Mr. Waldie said that he considered the communication a very ex- 

 cellent and complete investigation of the subject and that the conclu- 

 sions arrived at were very satisfactory. One point he thought not quite 

 perfectly proved, viz., that volatile acids only were concerned in the 

 action of the wood or the lead, but perhaps a better knowledge of the 

 details, to be had when the paper should be published, would make the 

 matter clearer. It had also occurred to him with reference to the 

 varieties of action of different kinds of wood, whether the presence of 

 oily or resinous matters in some might not possibly have some influence 

 in producing such differences. 



