NATURAL PHILOSOPHY. 163 



juring or staining the fabric, but at the same time give to them the re- 

 quired tints, and thus render them in harmony with other portions of 

 dress. 



Titanium. For the best essay upon titanium, with suggestions for 

 extracting and utilizing the metal. 



Smelting Zinc. For an account of the processes now in use for 

 smelting zinc ores, with suggestions for their improvement. 



Emigrants' Dwellings. For the best essay (for the information of 

 emigrants proceeding to new settlements), descriptive of the means of 

 treating existing natural products in any locality, such as earths, shells, 

 chalks, and limestones, woods, barks, grasses, etc., and applying them 

 in the construction of dwellings. Diagrams and illustrations of the 

 methods of applying materials should be given. 



Dutch Prizes for Investigation. The Dutch Society of Sciences have 

 also recently issued a prize-list of subjects for scientific investigation, 

 to which they invite answers to be sent in prior to January, 1865 ; and 

 the following are some of the topics selected : A gold medal is offered for a 

 paper on the Vertebrata (not including fishes) of the Indian Archipelago, 

 particularly those of Borneo, Celebes, and the Moluccas, and above all 

 those of New Guinea. In astronomy, a prize is offered for a deter- 

 mination, as exact as possible, of the errors of Hansen's Lunar Tables, 

 by the occultations of the Pleiades, observed during the last revolution 

 of the node of the lunar orbit. In electricity, the celebrated physicist, 

 Ruhmkorff, has obtained sparks of extraordinary length, by the induct- 

 ive machines which bear his name. Required: a determination, by 

 experimental and theoretical researches, of the laws which govern the 

 length and intensity of these sparks in machines of different sizes and 

 construction. Other questions are, What difference is there between 

 the perception of sounds with one and both ears ? Is fermentation, as 

 indicated by the researches of Pasteur and others, due to the develop- 

 ment of cryptogamia and infusoria ? and, if so, what is the exact de- 

 scription of these plants and animals and their mode of action ? Re- 

 quired : an investigation into the heat-conducting power of certain 

 insulating, or non-conducting substances, as glass, marble, etc. Another 

 is stated as follows : The researches of Gladstone and others have di- 

 rected the attention of physicists to the changes which the indices of 

 refraction of liquids undergo by a change of temperature. The Society 

 attach great importance to a knowledge of the relation between the in- 

 dex of refraction and the temperature, convinced as they are that this 

 knowledge would throw light on other very interesting points of the 

 theory of light. They therefore invite a series of exact researches on 

 these changes, in pure liquids and in solutions. The prizes are a gold 

 medal worth 150 florins, and an equal amount in money. 





