546 hitelligence and Miscellaneous Articles. 



an unaltered state. On boiling it with a concentrated solution of 

 bichromate of potash it undergoes no change, nor with free chromic 

 acid, i. e. sulphuric acid and chromate of potash, in which solution 

 it floats unaltered even after boiling for several hours. The acetic 

 solution has a strong bitter taste ; however, it does not appear to 

 produce any considerable physiological effects. 60 milligrammes, dis- 

 solved in acetic acid and taken early in the morning before breaking 

 fast, produced no effect ; nothing could be detected in the secretions. 

 25 millegrammes were given to a dog and 10 millegrammes to a bird, 

 but likewise without any effect. 



The elementary composition proved tlie perfect identity of the 

 substance prepared from lemon and orange pips, and gave as the 

 mean of several analyses, in 100 parts — 



Carbon 66*09 42 66-17 



Hydrogen 6'55 25 6'55 



Oxygen 27-36 12 27-32 



The formula is that of phloridzine, dried at 212° + 2 equiv. 

 oxygen. Direct experiments with reducing agents, such as sulphu- 

 rous acid, hydrochloric acid, sulphuretted hydrogen, hydrogen in 

 statu nascenti, and the electric current, afforded however by their 

 negative results the proof that this substance does not belong to the 

 phloridzine series, especially as the characteristic decomposition of 

 salicine by chromic acid was wanting. The combining weight 

 could not be ascertained, since it was impossible to obtain combina- 

 tions of this substance with other bodies. — Gottinger gel. Anz., 

 No. exxi. 1844. 



NEW METHOD OF SILVERING GLASS. 

 At a meeting of the Chemical Society Mr. Warington described 

 a new method of covering glass, by precipitation, with a coating of 

 metallic silver, the invention of Mr. Drayton. It consists in par- 

 tially precipitating, and thus neutralizing, to use the inventor's own 

 words, a solution of nitrate of silver by spirit of hartshorn, and add- 

 ing to the clear solution, after subsidence, oil of cassia previously 

 dissolved in spirits of wine. This compound mixture forms the sil- 

 vering menstruum, and is to be poured on to the surface of the glass, 

 or into the vessel intended to be silvered, the surfaces having been 

 previously rendered perfectly clean. Oil of cloves dissolved in spirit 

 of wine is then to be gradually dropped over the surface of the sil- 

 vering solution, or the two solutions may be rapidly mixed and then 

 applied immediately. In the course of about fifteen minutes a faint 

 purple cloud appears, and this gradually spreads through the whole 

 of the solution, and deepens in tint until it becomes opake, when the 

 operation is complete, and a most beautiful mirror is obtained ; as 

 thus produced, the reflecting surface is darker in its aspect and more 

 similar to the brilliancy of a very highly polished speculum. I'he 

 risk of breakage attendant on the usual process, by means of tin foil 

 and mercury, is also avoided, particularly where very large looking- 

 glasses are being constructed, and the great advantage obtained of 

 being enabled to silver uneven surfaces, as of lenses or cut glass. 



