250 ANNUAL OF SCIENTIFIC DISCOVERY. 



formed the common oxide of lead into a compound of that base with 

 peroxide of lead, &c. As far as his experiments go, they prove be- 

 yond a doubt that in a number of cases isolated oxygen produces the 

 same oxidizing effects as ozonized air or oxygen, He is, therefore, 

 inclined to think that light independent of heat exalts the chemical 

 affinities of oxygen, and that the slow oxidations which a variety of or- 

 ganic and inorganic matters undergo in the open air are, in part at least, 

 due to the exciting influence excited by solar light upon atmospheric 

 oxygen. Common bleaching is, of course, an instance of that sort of 

 oxidation. But Professor Schonbein goes still farther in his conjec- 

 tures as to the part which isolated atmospheric oxygen acts in the 

 economy of nature. He entertains the notion that the production of 

 electricity by clouds is intimately connected with the chemical powers 

 developed in atmospheric oxygen by solar light ; i. e. he presumes 

 that electricity has a voltaic origin resulting from an electro-motive 

 action of isolated oxygen on atmospheric moisture. Athenaum, 

 Nov. 



DISCOLORATION OF SILVER BY BOILED EGGS. 



IT is well known that silver, when brought in contact with eggs 

 which have been heated, is blackened, and that this discoloration is 

 owing to sulphuret of silver. It is usually admitted that this sul- 

 phuret is formed by the action of the sulphuretted oils supposed to 

 exist in the yolk of the egg. M. Gobley, not having found in this 

 body any thing of this nature, proceeded to examine into the causes 

 of the phenomenon. He found that the yolk of an egg at the common 

 temperature, and also when heated, does not discolor silver, even by 

 contact of several hours 1 duration. He farther found that albumen, as 

 procured from the egg, does not tarnish silver, but when heated it 

 gives it a brown tint, which is stronger as the heat is greater. He 

 therefore concludes that the discoloration of the silver is due to the 

 sulphur contained in the albumen, and not to that supposed to exist in 

 the yolk. By other experiments, he has ascertained that the sul- 

 phuret thus formed is not the result of the immediate action of the 

 sulphur upon the silver, but by the application of heat the sulphur 

 and the alkali of the albuminous matter react upon each other so as to 

 form a substance which is afterwards decomposed by this metal. 



