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■Intelligence and Miscellaneous Articles. 



using a large surface of solution so as to get the best effect. A 

 short distance over the surface was placed a sensitive film pro- 

 tected by aluminium-foil -^ of a millimetre in thickness and with 

 a lead star interposed. Two hours' exposure gave no result. The 

 experiment was repeated with acid solution of quinine, with which 

 five hours' exposure gave no result. 



I have also examined the Welsbach light for a'-rays. This light 

 is usually burned under a chimney which increases the brightness 

 but interposos glass between the source of light and the sensitive 

 film. Even without a chimney the light is bright. The experi- 

 ment was therefore made both ways. No a?-rays could be detected. 

 Nothing capable of passing through aluminium-foil t 1 q of a milli- 

 metre in thickness by five hours' exposure to the uncovered flame. 

 — American Journal of Science, May 1896. 



ON A NEW AREOMETER. BY L.-N. VANDEVYVER. 



The instrument is of glass, and consists of a cylinder di- 

 vided in two parts by a horizontal watertight diaphragm C. The 

 part B forms a small reservoir, closed at I) by a ground stopper. 

 To the cylinder is attached a stem carrying a scale 

 which may be graduated in different ways. We shall f^± t 6 

 assume that this scale is graduated for liquids 

 heavier than water, with densities between 1*00 

 (water) and 1*6, for instance. 



The liquid whose specific gravity is to be deter- 

 mined serves as ballast. 



Suppose it desired to verify the initial point of 

 the graduation. For this purpose the instrument 

 is inverted, and the part B is filled with distilled 

 water at a temperature t : the stopper is inserted 

 without allowing air to enter; the apparatus can 

 then be held upright without any fear of the stopper 

 falling out; it is wiped and placed in a cylinder con- 

 taining distilled water at the same temperature t. 

 The point to which it sinks should correspond to 

 the point TOO of graduation on the stem. 



The same process is repeated for the liquid whose 

 density is to be determined, care being taken to clean 

 the apparatus each time it is used ; distilled water 

 being ahvays used for the immersion. The liquid 

 introduced into B being denser than water the total 

 weight of the apparatus is greater, and it sinks to a 

 greater depth, giving a new level which represents 

 the density. 



By taking for extreme limits of the scale densities which are 

 sufficiently near together, the densimeter may be made very 

 sensitive. 



