366 Miscellanies. 



2. Iodine and bromine in mineral waters; by Professor Datt- 

 BENY. — The proportion of iodine to chlorine varies in every possible 

 degree, and even springs that are most strongly impregnated with 

 common salt, are those in which the smallest trace of iodine could 

 not be detected. The same remark applies to bromine ; whence 

 he concludes, that although those two principles may, perhaps, never 

 be entirely absent where the muriates occur, yet their relative distri- 

 bution is exceedingly unequal. The author conceives that these 

 analyses will tend to throw some light on the connection between the 

 chemical constitution of mineral waters and their medicinal virtues. 

 Almost the only two brine springs, properly so called, which have 

 acquired any reputation as medicinal agents, namely, that of Kreutz- 

 nach in the Palatinate, and that of Ashby de la Zouche, in Leicester- 

 shire, contained a much larger proportion than usual of bromine ; a 

 substance, the poisonous quality of which was ascertained by its dis- 

 coverer, Balard. The author conceives that iodine and bromine ex- 

 ist in mineral waters in combination with hydrogen, forming hydriodic 

 and hydro-bromic acids, neutralized, in all probability, by magnesia, 

 and constituting salts which are decomposable at a low temperature. 

 He has no doubt that a sufficient supply of bromine might be procured 

 from English brine springs, should a demand for this new substance 

 ever arise. — Id. p. 337. 



3. Illumination of Light Houses. — (Lieutenant Drummond.) — 

 A small ball of lime only three eighths of an inch in diameter, ignited 

 by the combustion of oxygen and hydrogen, emitted a light so bril- 

 liant as to be equal in quantity to about thirteen Argand lamps, or 

 one hundred and twenty wax candles ; while in intensity or intrinsic 

 brightness, it cannot be less than two hundred and sixty times that 

 of an Argand lamp. In the best of the British revolving lights, as 

 that of Beachy Head, there are no less than thirty reflectors, ten on 

 each side. If, then, a single reflector, illuminated by a lime ball, be 

 substituted for each of these ten, the effect of the three would be 

 twenty six times greater than that of the thirty. On account of the 

 smaller divergence of the former, it would be necessary to double 

 their number, placing them in a hexagon, instead of a triangle. In 

 this case the expense is estimated at nearly the same. This method 

 was lately tried at Purfleet, in a temporary light house, erected for 

 the purpose of experiments by the corporation of the Trinity house, 

 and its superiority over all the other lights, with which it was com- 



