sis Mr. Warington on some Sjyecimens of Greeti Glass. 



evolution of its carbonic acid from its weaker affinity, and that 

 then, by the absorption of carbonic acid from the atmosphere 

 it is again deposited as carbonate of magnesia, thus making 

 its affinity stronger ; the second position being directly con- 

 tradictory to the first. 



On trying a repetition of the same experiments with the 

 same materials, but omitting the essential oil, and going 

 through precisely the same routine, I obtained from 0*50 to 

 0*70 gr. of carbonate of magnesia by evaporation as the ave- 

 rage results of many trials ; so that 1 consider from these data 

 we may fairly conclude no combination'of the magnesia and oily 

 acids had taken place, but that it was simply a solution of the 

 earthy carbonate in the distilled water; nevertheless, in many 

 of the experiments, the presence of the different oils evidently 

 affected the solvent power of the water and thus directly in- 

 fluenced the quantity of carbonate of magnesia taken up; and 

 the resin existent in some of the old oils will account for the 

 occasional increase of weight over this quantity, for it has been 

 shown that this resin is soluble to some extent in water. 



There can be no doubt, from the above experiments, that 

 any insoluble substance in a fine state of division will answer 

 the same purpose as the carbonate of magnesia much better, 

 as, for instance, very fine porcelain clay, finely-divided silica, 

 powdered glass, pumice-stone, &c. I am not aware how the 

 use of carbonate of magnesia for the extemporaneous forma- 

 tion of these waters originated, except with the pharmaceutist 

 as being a material generally at hand, and it is well known to 

 have been the substance usually employed for this purpose for 

 a great number of years, and was, I am informed, used by the 

 perfumers to produce the same results long before its intro- 

 duction for medicinal preparations. 



LXXXII. Oti some commercial Specimens of Green Glass. 

 By Robert Warington, Esq.^- 



SOME short time since some green glass wine bottles were 

 put into my hands for examination, the inner surface of 

 which was covered with a thin film, having a dull and slightly 

 opake appearance. The question to be solved was, the pos- 

 sibility of removing this so as to restore the glass to its origi- 

 nal transparency. My first impression, from the general 

 appearance of the bottles, was that this dullness was to he at- 

 tributed to some matter mechanically adherent to the surface, 

 and that it probably arose from their having been washed with 



* Communicated by the Chemical Society ; having been read December 

 16; 1844. 



