398 Foreign Literature and Science. 



43. Preservation from rust. — It has been ascertained by 

 Arthur Aikin, secretary to the Society of arts and manuCac- 

 tures, that melted Caoutchouc is an excellent material for 

 the above purpose. Plates of iron and steel, lialf covered 

 with this substance, were exposed six weeks in a laboratory, 

 and at the end of this time the uncovered parts were almost 

 entirely corroded, while the varnished parts were complete- 

 ly preserved. 



Caoutchouc must be melted in a close vessel. It requires 

 about the same temperature for fusion as lead. When 

 melted it must be stirred by a hoi^izontal agitator, the han- 

 dle of which rises through the cover, to prevent its being 

 burnt at the bottom. 



Mr. Perkins has perfected this process, by dissolving the 

 caoutchouc in spirits of turpentine. The varnish thus ob- 

 tained, after being suitably dried, becomes firm and does 

 not change by exposure to moisture. It is laid on with a 

 soft brush, and may be removed at any time by dipping the 

 brush in hot spirits of turpentine. Mr. Perkins uses this 

 varnish to preserve his engraved steel plates. 



44. Geology. — There is found in the northern provinces 

 of Russia, besides the bones of the mammoth and some oth- 

 er remarkable objects of natural history, a kind of fossil 

 wood, in part petrified, and in part decomposed or rotten. 



Professor Kounizin remarks that he formerly entertained 

 the popular opinion that these trees had been blown down 

 and gradually" covered with sand and mud in or near the 

 places where they grew. But he is now convinced that 

 this is an error, and that they must have had an origin, 

 quite remote from their present situation. For 1st. -They 

 are covered to a great depth with earth, in the form of beds 

 parallel to the surface. 2d. All the trees have their tops 

 directed toward the same quarter, and they are only inclin- 

 ed. 3d. Almost all have been broken by an irresistible 

 force, the oaks alone retaining their roots. 4th. The bed 

 of earth under which they are found is so thick that the wa- 

 ters of the rivers do not reach them. This earth is partly 

 sand and partly clay. The trees that are covered with dry 

 sand are quite rotten and moulder speedily into dust. 

 Those under moist sand are still in good preservation. The 

 pines and firs are more decomposed than the others, but 



