PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 423 



woods : Oak (heartwood), of the age of at least forty years; Asli, of the 

 age of at least twenty-five years, the whole of the wood except the liber 

 and the bark; Pine of the same age, and Poplar of the age of twenty years. 

 Analyses of the same trees, five jiears old, are also to be made, with the 

 view of comparing the composition of the wood at different ages. Speci- 

 mens of the wood and of the principles obtained from them must be sent 

 with each paper. 



Mineral Waters. 



Mr. Scoutetten, in a memoir to the French Academy of Sciences, " On 

 Kesearches on mineral waters and the cause of their active properties," says 

 these waters, on coming in contact v\'ith the electro-magnetic currents in 

 the bosom of the earth, undergo a sort of allotropic condition, which does 

 not last, unfortunately, when the water comes to the surface, but is gone 

 in three days at most. 



EXTRACTING AND PRESERVING AROMA. 



Mr. C. R. C. Tichborne states in the Chemical News he has successfully 

 used glycerine, not only for pv6serving flowers but for extracting their 

 aromatic properties. Flowers preserved for two years in glycerine have 

 yielded on distillation perfume equal to the most recent product. In cases 

 where the aroma of the flower is so delicate as to be much injured or 

 entirely destroyed by the application of heat, it may be macerated with 

 glycerine, which should be expressed and again treated with flowers, until 

 the recipient is thoroughly saturated v.ith ottar. The extraction is perfect 

 as evidently the glycerine has a great affinity for volatile oils. Fresh mint 

 suspended over a thin stratum of glycerine imparts its odor in a short tim€> 

 to the fluid. The glycerine saturated with ottaris diluted with water and 

 shaken with a small quantity of choloroform. After well agitating the 

 latter subsides, carrying with it nearly' the whole essential oil ; it should 

 be separated, filtered and allowed to evaporate spontaneously. In working 

 on a large scale evaporation by artificial heat may be resorted to, the boil- 

 ing point of the fluid being very low; the last portion, however, should be 

 separated by spontaneous evaporation. The glycerine to be used should 

 be odorless and have a specific gravity of 1 24 at 60 deg. F. .The same 

 glycerine may be employed over and over again by diluting aad pass- 

 ing it through charcoal, and" afterwards evaporating it to the desired 

 gravity. 



Haloid Salts of Copper. 



Regnault has presented another paper to the French academy on these 

 salts, in which he describes their photographic properties. The bromide 

 of copper is the most sensitive to light, and the picture may be fixed by 

 employing the ordinary hyposulphite with care. Iodide of copper is less 

 sensitive to light, and the fluoride is the least so, of the series. 



Alcohol from Coal Gas. 



Berthelot, in his new work on Organic Synthesis, demolishes the pro- 

 position to make alcohol from coal gas. The process is shown to be very 

 expensive and the arti-f:]e produced very impure. 



