26 THE GRAPE. 



wine was Bischof.* He discovered it in Rhine and 

 Moselle wine when precipitated with ammonia ; that 

 phosphate of lime and phosphate of ammonia and mag- 

 nesia were also mixed with it, is of course understood. 



Alumina was formerly believed to exist in many 

 vegetables, but this supposition has been proved to 

 be erroneous, and it appears to be found really in 

 very few plants. It would certainly be very remark- 

 able did it really exist in grape juice. 



"Winkler, some years since, gave us the explanation 

 of this remarkable phenomenon. "When he had the 

 grapes washed in pure water, and afterwards pressed, 

 the alumina was to be found in the juice. Its origin 

 is, therefore, not the plant, but the dust which sticks 

 to the fruit, and adhering to the juice during the 

 process of pressing, is afterwards (in so far as it 

 contains soluble alumina,) taken up by it. 



Alumina may therefore actually exist in wine, but 

 is not to be regarded as a constituent of the plant. 



(running burnt 31*85 raisins and obtained O3 ashes, 

 which taken in conjunction with the stones and skins, 

 gives 0'94 per cent. These were treated with hydro- 

 chloric acid, and the liquid thus obtained was warmed 

 and filtered with a considerable quantity of liquid 

 potash ; to this clearer liquid hydrochloric acid, and 

 after that ammonia were added. A slight thickness 

 ensued, which, however, manifested no trace of alu- 

 mina, and a little phosphate of lime was dissolved, as 



* Die vulcanischen Mineralquellen Deutschlands, s. 61. 





