96 ANNUAL OF SCIENTIFIC DISCOVERY. 



large cocks. The reciprocating motion is attained by one cylinder operating 

 upon the cock of the other; and the blast of air obtained by these feeders is 

 continuous, but varied by a steam equilibrium throttle-valve, which the res- 

 ervoir of the bellows closes as it becomes thoroughly inflated. The engine 

 is under the immediate control of the organist by suitable gearing leading to 

 valves in the cistern. 



RESTORATION OF TARNISHED SILVER. 



Sometimes silver instruments become so completely tarnished and discol- 

 ored, that by no ordinary means can they be cleansed. Professor Bottger 

 states that by electrolysis their color can be restored in an incredibly short 

 period. To effect this a saturated solution of borax in water, or a moderately 

 strong solution of caustic potassa, is brought into a state of active ebullition ; 

 and with this the discolored object, laid in a zinc sieve-like vessel, is moist- 

 ened. If a zinc sieve be not at hand, we may attain the same end by touch- 

 ing the object, when it has been dipped in the boiling fluid, with a zinc rod. 



ON THE DURABILITY OF ZINC WHITE. 



A curious lawsuit has been tried in Paris during the past year. M. Gudin, 

 the well-known French marine painter, demanded 8001. damages from a 

 tradesman, for having sold his canvasses prepared with white of zinc, which 

 is a substance so injurious to oil colors, that several of his paintings became, 

 in a comparatively short time, cracked and spoiled. In support of his de- 

 mand, he stated that one of his paintings, a View on the Coast of Asia, had been 

 returned to him, and he had had to restore 3201. , the amount received for it; 

 and that after painting three others, for which he was to have received 700?., 

 he had not been able to deliver them. The court awarded M. Gudin an in- 

 demnity of 480Z. 



RAZOR PAPER. 



This article supersedes the use of the ordinary strop; by merely wiping the 

 razor on the paper, to remove the lather after shaving, a keen edge is always 

 maintained without further trouble; only one caution is necessary, that is, 

 to begin with a sharp razor, and then the paper will keep it in that state for 

 years. It may be prepared thus : 



First procure oxyd of iron (by the addition of carbonate of soda to a solu- 

 tion of persulphate of iron), well wash the precipitate, and finally leave it of 

 the consistency of cream. Secondly, procure some good paper, soft, and a 

 little thinner than ordinary printing paper; then, with a soft brush, spread 

 over the paper (on one side only), very thinly, the moist oxyd of iron; dry it, 

 and cut into pieces two inches square. It is then fit for use. 



ASSYRIAN CIVILIZATION. 



Sir Henry Rawlinson, the eminent oriental scholar, in a recently published 

 communication, thus concludes a sketch of the range of Assyrian civilization : 



"Among them (the ornaments) are some which anticipate inventions be- 

 lieved till lately to have been modern. Transparent glass (which, however, 

 was known also in ancient Egypt) is one of these; but the most remarkable 

 of all is the lens discovered at Nhnrud, of the use of which as a magnifying 



