1885.] A. Pedlcn' — Corrosion of Lead Linings of Indian, Tea Chests. IGl 



reiterates the position he had previously taken up. His conclusions 

 may be fairly well summed up in the following statement : " The 

 chest is full of tea which has been fermented, its fermentation arrested 

 rapidly, and the tea is rapidly enclosed in a case and shipped to 

 Europe. Is it improbable that the acetification of the fermented tea 

 may not be the primary agent in the decomposition of the wood and 

 the consequent corrosion of the lead ? Having arrived at this conclusion 

 I had little difficulty in producing from tea an acetous organic acid 

 which rapidly corroded lead ; so I have no doubt this volatile acid on 

 escaping through the lead lining would soon establish in certain timbers, 

 especially green and unseasoned ones, corresponding acetification, bat I 

 am convinced that we have to look to the tea itself and to some imper- 

 fection in its manufacture, as the primary exciting agent in the corro- 

 sion of the lead and the damage of the commercial article." 



In view, then, of these centradictory statements as to the cause of 

 the corrosion of the tea-leads, Dr. Wigner and Dr. Voelcker being of 

 opinion that the cause was the wood, though of course their proof was 

 incomplete, and Dr. Watt holding that the cause was to be found in the 

 tea, I commenced the following experiments. 



From a practical point of view the first thing which it was desirable 

 to settle was whether the tea or the wood of the chests was the active 

 agent in inducing the corrosion of the lead. To test this view, certain 

 boxes of tea were specially prepared, and they were then handed over 

 to me by the Indian Tea Association. 



Three boxes represent the matter typically. 



No. 1 was a half chest containing 40 lbs. of pekoe souchong tea of 

 ordinary manufacture. The half box was made entirely of wild mango 

 wood (Mangifera indica), damp and unseasoned- 

 After being kept in the ordinary way for several weeks this box was 

 examined. On being opened the upper surface of the lead next the wood 

 was found to be almost entirely covered with a white powder, which on 

 examination was found to be principally " white lead." The lead was 

 largely corroded over the whole surface, and in fact eaten through in cer- 

 tain places. There were several clear cases of perforation, and, examined 

 under a magnifying glass, the perforations were surrounded on the upper 

 surface with very extensive corrosion. The lead was then cut off from 

 the chest, and the surface next the tea examined ; over the greater part it 

 was quite bright and free from corrosion, though in certain parts it was 

 slightly tarnished. The perforations were also examined from the under 

 surface, and there was no trace of corrosion round the edges. E\^en in 

 this, which should be the most favourable position for corrosion if the 

 corrosion is caused by the tea, no corrosion was seen. 



