112 ANNUAL OF SCIENTIFIC DISCOVERY. 



tliroimh the thin covering of asphalt upon the copper surface. When com- 

 pleted, the rollers are placed in dilute acid, which etches into the copper 

 where the paint has been removed, and thus accomplishes the engraving." 



NOVEL COAL SIFTER. 







A novel sifter, only requiring the refuse from the grate or stove to be 

 poured into a hopper, when it does its own sifting by gravity, is constructed 

 with an inverted cone at the bottom, and a direct one over it, both being 

 made of woven wire, and forming the screen. These are surmounted with 

 a hopper, into which the coal and ashes are poured, when they fall upon 

 the apex of the cone, slide down its periphery, discharge round the inside 

 base of the inverted cone, and so on, the ashes falling through an orifice at 

 its lowest point. The screens are so arranged as to be easily removed and 

 cleared, should they become clogged. It might be applied by farmers to 

 assorting such seeds, fruits, potatoes, etc., as are round enough to roll over 

 the cones. For coals it must be of great value, should it not choke too often 

 by filling the meshes with irregular pieces. N. Y. Tribune. 



IMPROVEMENT IN THE MANUFACTURE OF STARCH FROM CORN. 



M. Watt, of London, has obtained a patent for making starch from Indian 

 corn in the following manner : He steeps the corn in w r atcr ranging in tem- 

 perature from 70 to 140 Fah., for about a week changing the Avatcr at 

 least once in every twenty -four hours. A certain amount of acid fermenta- 

 tion is thus produced, causing the starch and refuse of the corn to be easily 

 separated afterwards. The swollen corn is ground in a current of clean soft 

 water, and the pulp passed through sieves, with the water, into vats. In 

 these the starch gradually settles to the bottom; the clear water is then run 

 off by a tap, and the starch gathered and dried in a proper apartment for 

 the purpose. 



FLEXIBLE IVORY. 



According to the process of Geisler, in Switzerland, articles of ivory are 

 placed in a solution of phosphoric acid, of 1'130 specific gravity, and left 

 there until they assume a transparent aspect. After this, they are taken 

 from the acid, washed off in water, and dried with soft linen cloth. The 

 articles arc now as soft as thick leather; they become hard in the open air, 

 and when placed in warm water they assume their former softness. 



The application of such ivory for nipples of nursing-bottles, or for covers 

 of sore breasts, and for similar articles, is of importance. The change evi- 

 dently consists in a solution of a portion of the lime, producing a compo- 

 sition containing a smaller percentage of lime than ivory. 



ON THE OXIDATION OF IRON. 



At a late meeting of the Manchester Philosophical Society, H. M. Ormerod 

 produced two specimens of iron used in buildings, which have become so 

 oxidized as to injure the structures in which they had been used. An iron 

 cramp, taken from a buttress of the Manchester Parish Church, had become 

 treble its own thickness by rust, and had thus split the building in the cen- 

 tre, and lifted about twelve feet of the wall. It was inserted about ninety 

 years ago. The other piece of iron was a small wedge, taken from the 



