?8 ANNUAL RECOKD OF SCIENCE AND INDUSTRY. 



tacked by sodium amalgam. Two series of salts of acridine 

 have already been prepared by the authors, and numerous 

 compounds with other substances examined by them. 21^4, 

 August, 1871, V 08. 



ACTION OF LIGHT OX PETROLEUM. 



According to recent investigations, when petroleum oils 

 are exposed under certain conditions to the sunlight, they 

 absorb from the air oxygen, which is converted into ozone. 

 "No chemical combination takes place between the oil and the 

 ozone, but the latter remains free, and oxydizes any substance 

 with which it comes in contact. In oils containing ozone the 

 smell is materially modified ; they burn w T ith difficulty, and 

 attack rapidly the stoppers of the vessels containing them, 

 especially if the stoppers be composed of cork. When glass 

 vessels are used it has been found that the color of the glass 

 exercises a great influence over the absorption of oxygen. 

 Decolorized oils exposed in white glass vessels to the action 

 of sunlight turn yellow, become charged strongly with ozone, 

 and burn with difficulty. This is principally the case with 

 the American petroleums. They should, therefore, be kept 

 in metallic vessels, or, if glass be used, it should be shaded as 

 much as possible from the sun. 13 (7, August 11,1870,1151. 



BRITTLE SILVER. 



Attention has lately been directed to the change which 

 alloys of silver experience by long burial in the earth, and 

 several articles have appeared in scientific journals on the 

 subject ; one based upon the examination of ancient Roman 

 vases found buried in the Black Forest of Germany ; and 

 another, by Professor Church, in reference to the specimens 

 lately exhumed in the island of Cyprus by Mr. Di Cessnola, 

 the resident American consul. These latter were found upon 

 the site of the ancient city of Idalium, and lay % claim to an 

 antiquity of at least 1500 years, during which time they have 

 become covered externally, to the depth of about one thirti- 

 eth of an inch, with a crust, which proved, upon analysis, to 

 be composed principally of finely divided silver, mixed with 

 the chloride and sulphide of that metal, and a little basic car- 

 bonate of copper. Beneath this layer the substance of the 

 metal appears white, metallic, and uniform, but very brittle, 



