Scien/ifJr Jn(Migence — Mi.^cf7hi?ieo>/s. IHl 



to tlie scheererite of Uznach, in Switzerland, that they wore at first 

 taken for that mineral suhstance. M. Forchhanimer, who has 

 studied these crystals, has found that they are composed of two 

 substances, to one of which he gives the name of Terov tine, on ac- 

 count of the facility with which it enters into a state of fusion ; 

 to the other, that of PlivlJorctinc, hGCuuse it crystallizes in fine 

 leaflets. These two substances may be separated, by dissolving 

 the crystals in boiling alcohol.— Froin VInstitut., June 16, 1642, 



p. 217. 



30. On the Preservation of Flowers.— To preserve flowers fresh. It 

 is now, alas ! a long eighteen years ago since we first saw, in 

 the drawing-room of a gentleman now no more, in the hot, dry 

 weather of the dog-days, flowers preserved day after day in all 

 their freshness by the following simple contrivance :— A flat dish 

 of porcelain had water poured into it ; in the water a vase of 

 flowers was set ; over the whole a bell-glass was placed, with its 

 rim in the water. This was a "Ward's case" in principle, 

 although different in its construction. The air that surrounded the 

 flowers, being confined beneath the bell-glass, was constantly 

 moist with the water that rose into it in the form of vapour. As 

 fast as the water was condensed, it ran down the sides of the 

 bell-glass into the dish ; and if means had been taken to enclose 

 the water on the outside of the bell glass, so as to prevent its 

 evaporating into the air of the sitting-room, the atmosphere 

 around the flowers would have remained continually damp. 

 What is the explanation of this ? Do the flowers feed on the 

 viewless vapour that surrounds them ? Perhaps they do ; but the 

 great cause of their preserving their freshness, is to be sought in 

 another fact. When flowers are brought into a sitting-room they 

 fade, because of the dryness of the air. The air of a sitting-room 

 is usually something drier than that of the garden, and always 

 much more so than that of a good green-house or stove. Flowers, 

 when gathered, are cut off from the supply of moisture collected 

 for them by their roots, and their mutilated stems are far from 

 having so great a power of sucking up fluids as the roots have. 

 If, then, with diminished powers of feeding, they are exposed to 

 augmented perspiration, as is the case in a dry sitting-room, it is 

 evident tiiat the balance of gain on the one hand by the roots, 

 and of loss on the other hand by their whole surface, cannot be 

 maintained. The result can only be their destruction. Now, fo 

 place them in a damp atmosphere, is to restore this balance ; 

 because, if their power of sucking by their wounded ends is 

 diminished, so is their power of perspiring ; for a damp atmos- 



