580 Transactions of the American Institute. 



It is never attacked by white ants, nor by the teredo navalis, which 

 abound in tropical and semi-tropical seas. It is therefore of great 

 value in hot climates for ship-building, pier and railway construction, 

 as Avell as for the interior of buildings and for furniture. The immu- 

 nity of this wood from the attack of insects, whether land or marine, 

 has been proved by analysis to be due to the presence of tannic acid. 

 The other variety is the Tooart wood. It has a very close grain, and 

 is so extremely hard that it cannot be split, and will endure great 

 heat without rending. On account of its non-liability to split, it has 

 been suggested for use in gun-carriages. 



Mr. J. K. Fisher — Might not other kinds of wood' be made imper- 

 vious to the ants by the use of tannic acid in some way ? 



The President — Various attempts have been made to protect com- 

 mon woods from the ants, but they have not been completely 

 successful ; and the w x ood prepared by nature is cheaper than anything 

 else. I do not myself believe that tannic acid has the power of pro- 

 tecting wood. 



Prof. J. Phin — The great difficulty is that the ants do not eat the 

 wood ; they merely burrow into it. They gnaw it and throw the dust 

 out. Poisoning the wood, therefore, does not affect them. 



Mr. Fisher — This is a matter of much importance in the fine arts. 

 Many of the finest pictures, painted upon panels, have been entirely 

 destroyed by worms. The experience of 350 years shows that pic- 

 tures upon canvas are not as durable as those upon panels, provided 

 we can get good panels. They are frequently made of cracke/1 and 

 knotty wood. What is wanted is wood impervious to worms, imper- 

 vious to rotting, and not liable to crack or split. And as to the 

 additional cost of half a dollar per square foot, half an inch thick, 

 would not be an objection ; chemists are' not limited in their use of 

 means in preparing the wood. 



Mr. Robert "Weir — Is not the millboard very durable ? 



Mr. Fisher — Yes, but it bends and gets out of shape. 



Mr. "Weir — Boards are also made of paper — of papier-mache. 



Mr. Fisher — I think the best substance will probably be found to 

 be prepared wood. 



III. Waterproofs. 



The "Lounger" of the Illustrated Times says: By the way, 

 touching water-proofs, I think I can give travelers a valuable hint or 

 two. For many years I have worn india-rubber waterproofs, but I 

 will buy no more, for I have learned that good Scottish tweed can be 



