70 Effect uf Heat and Cooling on the Colour iif the Itubij. 



It consists of two cages of wire, which are suspended the 

 one under the other to a sensitive spiral spring. The lower 

 cage being immersed in water, the weight of the body in air 

 will first be indicated by the tension of the spring when it is 

 2)laced in the upper cage; by then removing it to the lower 

 one its weight in water will be pointed out on the graduated 

 scale: and Mr. Creighton gives a formula for ascertaining the 

 specific gravity from these two observations, without recurrmg 

 to the usual tedious calculations. 



auseniuretted hydrogen gas. 



The following method of preparing this gas is proposed by 

 M. Serrulas: Iwo parts of bitartrate of potash, two parts of 

 antimony, and one part of arsenious acid are to be mixed and 

 well triturated in a mortar, and then strongly heated for two 

 hours in a close crucible. The alloy thus produced, when in 

 contact with water produces hydrogen gas saturated with 

 arsenic, which may be preserved for any length of time in 

 close vessels. The gas is procured by putting, quickly, about 

 150 grains of the alloy, previously reduced to coarse powdei', 

 under a jar filled with water, and inverted in a glass basin 

 containing water. — Journal ele Physique, 



ANALYSIS OF BLACK HELLEBORE. 



A late analysis of the roots of black hellebore by MM. Fe- 

 neuUe and Capron yielded, — 1. a volatile oil; 2. a fatty matter ; 

 3. a resinous matter; i, wax; 5. a volatile acid ; 6. a bitter prin- 

 ciple ; 7. mucus ; 8. alumina ; 9. gallate of potash and aci- 

 dulous gallate of lime; 10. a salt with an ammoniacal base. — 

 Journal de Phar. 



ANALYSIS or THE ROSE. 



From 1000 grammes of the petals of the white Provencal 

 rose lately analysed by M. F. Cartier, he obtained by in- 

 cineration a residuum of 99 gr., containing subcai'bonate of 

 potash, phosphate, and traces of muriate of potash, carbo- 

 nate of lime, phosphate of lime, traces of phosphate of mag- 

 nesia, silica, and oxide of iron. The quantity of the last was 

 ascertained to be 12*5. From 1000 gr. of red roses he pro- 

 cured only 50 of residuum, containing no more than 4' oxide 

 of iron. — Journal de Phar. 



EFFECT OF HEAT AND COOLING ON THE COLOUR OF THE RUBY. 



Dr. Brewster relates the following singular changes in the 

 colour of rubies while cooling after exposure to a high degree 

 of heat. At a high temperature the red ruby becomes green : 



as 



