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509 



with the properties that Scheele had assigned to his malic acid. 

 This was the grand question, and conceiving that, until it be 

 determined, the presumed identity of sorbic and malic acids is 

 a premature and unwarrantable assumption, I undertook the 

 inquiry in the following manner : 



" A quantity of unripe apples, sufficient to afford four gal- 

 lons of juice, were crushed to a pulp, and subjected to the ac- 

 tion of a screw-press. The juice, after standing twenty-four 

 hours, was poured off the faeces, boiled, and strained. To this 

 was added solution of acetate of lead while any precipitation 

 ensued ; the precipitate was filtered off, and allowed to drain 

 for several days. It was then boiled, for five minutes, in two 

 gallons of water, and the liquor was filtered while very hot. 

 The remaining mass was again boiled in two gallons of water, 

 and the hot liquor filtered. The boiling and filtration were 

 repeated until both processes were performed in all six times. 

 In the first four waters, crystals appeared after twenty-four or 

 forty hours ; in the last two there were none. The matter 

 which remained undissolved on the filter, now incapable of 

 furnishing crystals, was decomposed by a slight excess of very 

 dilute sulphuric acid ; and, everything soluble beingwashed out 

 of the sulphate of lead, all the washings were collected, filtered, 

 and mixed with a new portion of solution of acetate of lead. 

 The precipitate thus produced was separated by the filter, al- 

 lowed to drain well, and after being boiled in two gallons of 

 the water which had been used in the former processes, the 

 liquor was filtered. The pasty mass remaining on the filter 

 was again boiled in two other gallons of the former water, 

 and the solution filtered. This boiling in new portions of the 

 original water, and filtering, were repeated in all six times. In 

 each of the first four waters, after forty hours, beautiful white 

 crystals were formed ; but little in the fifth, and none in the 

 sixth. These processes of decomposition by sulphuric acid, 

 recomposition by acetate of lead, boiling in divided waters, fil- 

 tering, and crystallizing were repeated until the original preci- 



