PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 381 



to the next plate below b}' the pipe C, and then flows to the centre of this 

 plate, passini^ throug'h a similar pipe to the next plate and so on to the 

 bottom, and has its exit by a \)\\w (not represented) near the bottom of the 

 heater and connected with the supply pump. 



The lowest, third and tup clKinncl plates are of less diameter than the 

 inside of the encasing- cylinder, to allow the steam to pass around them. 

 The second and fourth chaniud plates fit close so that the steam may pass 

 through the tube in their centres. 



The efficietic}' of this heater is due to the large surface of water exposed 

 which being in rapid motion constantly brings new surfaces to the action 

 of the steam. ( 



Its efficiency, ease of detaching and cleansing, and the sediment and 

 scale b(M'ng deposited in it and saved from injuring the boiler, and economy 

 attending its use, give it very great value. 



It should be placed a foot or more higher than the pump, so that the pres- 

 sure will raise the pump valve. 



The Hermetical Barrel. 



One of Robbins' non-leaking, non-evaporating barrels was exhibited, con- 

 cerning which Dr. AV. H. Dwindle desired to say a few words. It is a well 

 settled fact, that with all our improvements in the arts, we have not before, 

 had a wooden vessel constructed in which fluids could be transmitted from 

 place to place, without a great loss by evaporation through the pores of the 

 wood. The loss of all fluids thus kept is considerable, but of petroleum 

 and naphtha, because of their permeating qualities, the annual loss is esti- 

 mated by millions. There is an absolute leakage, distillation and sweating 

 of these fluids through such barrels, of from eight to thirty per cent. 



The idea of constructing a barrel that would prevent all this loss was 

 suggested to Mr. Robbins by nature. Why is it that the trees, especially 

 those of tropical climates, retain their volatile constituents? It is because 

 the bark and the inner portion of the tree contain oily substances and that 

 one of the constituents of the tree is potash. Mr. Robbins in experiment- 

 ing found a barrel would take up a pint of ordinary- water in twenty-four 

 hours, while in the same time a similar barrel would absorb nineteen pints 

 of a solution of potash. To restore to the wood some of its original power 

 was the aim of Mr. Robbins, which resulted in the discovery and invention 

 which he has patented. His process is to give the exterior of the barrel a 

 coating of hot linseed oil, and the inside an alkaline covering, such as hot 

 soap suds. A barrel thus prepared, forms a complete barrier to all evapo- 

 ration or leakage through the pores of the wood, so that it might be said 

 not a drop of petroleum confined in it can escape. Numerous barrels treated 

 in this manner have been filled at the oil wells in Pennsylvania and trans- 

 ported to this city, where on examination it was found they had not lost 

 the least of their contents, while other barrels filled and brought to the city 

 at the same time had lost from three to four gallons each. 



