Society of Pharmacy at Paris. 57 



If the filtered liquor does not contain more free acid, 

 add a little di-nilied vinegar *; then evaporate to dryness ; 

 and if we wish to obtain the acetate of potash well cleaned, 

 we must, at the end of the evaporation, manage the fire 

 properly, and not stir it; but in this case it is not so white 

 as when we separate it with a silver spatula, and throw it 

 on the edges of the basin as fast as it is formed at the sur- 

 face of the liquid : this salt will also be whiter it' dried by 

 small portions. 



On exposing for about 20 davs to the solar rays the 

 liquor filtered over charcoal, the author obtained a salt 

 much whiter: hence he thinks that the same result might 

 be obtained, by exposing la the light an acetate of potash 

 made from distilled vinegar, without being filtered through 

 charcoal. 



He regrets that he has been unable to collect some 

 important facts relative 10 the colouring matter: he re- 

 marked that it was partly ,.recipitated after saturation ; that 

 it is a little soluble in water, and that a portion remains in 

 solution in the liquid acetate of potash; that after having 

 filtered distilled vinegar through very pure charcoal, like 

 that which is produced from crvstallized sugar, we no 

 jonger obtain, on saturating it with crvstallized carbonate 

 of potash, the same precipitate as before filtration. 



The author of the memoir concludes, therefore, — 



1. That the colouring matter of the acetate of potash be- 

 longs to a vegetable substance contained in distilled vinegar. 



2. That this colouring matter is destroyed by charcoal. 



3. That an excess of alkali, when we evaporate the result 

 pf the saturation of distilled vinegar by potash, may in- 

 fluence the whiteness of the acetate'of potash. 



4. That in order to obtain the earth pure white and sa- 

 turated, it is sufficient to filter a concentrated solution of it 

 over a small quantity of charcoal in powder; to keep in it 

 afterwards to the end of the evaporation an excess of acid, 

 by adding from time to time distilled vinegar, and to ex- 

 pose it for some days to the solar li|$ht. 



Jn a note which terminates this" memoir, the author 

 says, that according to the valuable observation of Messrs. 

 Vauquelin, Pou tier and Derosne, he .obtained two hecto- 

 grammes i,f excellent acetic ether, by rectifying over pot- 

 ash the first products of the distillation of 70*litres of distil- 



< * A little acetic acid (radical vinegar) would he preferable ; very little 

 » Decenary when care has been taken to iilter the liquor in the neutral 

 •dates we must also take care that it is not acid, in consequence olfhe H-ne 

 wi^ch is in ;he charcoJ. ^^ c 



