T reparation of the Citric Acid. liy 



wanting to complete the thirty, which, according to the pro- 

 portion before eftablifhed, ought to be produced by fix ounces 

 of citrate, remained in the mother water. But, as it ap- 

 peared to me that there could not be more than half a dram 

 in this refiduum, it is evident that the citric acid will be, as 

 I have before indicated, from two to three below 70 percent. 



VIII. Though the citrate of lime be white and well wafhed, 

 it always retains fixed in it a little extractive matter, the co- 

 lour of which is found again, after its decomposition, in the 

 liquors. It thence happens that it is difficult to obtain the 

 cryrtals white without two new cryftallizations at leaft. The 

 citrate of lime, in this refpedi, exhibits the fame phenomena 

 as the other earths and earthy falts, which readily adhere and 

 fix themfclves to the colouring parts. The citrate, which 

 may be feparated from the juice of verjuice by chalk, is, in 

 particular, attended with this inconvenience : — if it be not 

 immediately feparated from the liquor, it aflumes a violet 

 colour, which cannot be taken from it by repeated warnings* 



Four ounces of lemon juice employed in the fucceeding 

 experiments, evaporated in the fun, left 48 grains of dry re- 

 fiduum. But the citric acid, having been found to be 34, 

 the extract, gum, and a little malic acid, formed together 14 

 grains. Thefe 48 grains, of different principles, were then 

 diluted in 3 ounces 7 drams and 24 grains of water; that is. 

 to fay, they formed a ninety-fourth oFthe lemon juice. 



IX. Confequences . 



It follows, from thefe refearches, that mucilage and ex- 

 tractive matter, as Schcele difcovered, are the corruptible or 

 fermentable principles of the lemon juice; and as none of 

 the recipes propofed for its concentration are capable of de- 

 priving it of thefe principles, it is necefiary to have recourfe 

 to the method of that author. This method will be very 

 practicable on a large fcale, but it will require bafons of filver 

 or fine tin. It will be abfolutely necefTary to profcribe from 

 the laboratory earthen veffels varnifhed with lead, but not 

 (tone ware, becaufe the lead which enters into their coating 

 is fo far vitrified as to be proof againft any attack. One can 

 hardly believe that the fyrup of lemons commonly fold in the 

 fhops does not contain oxide of lead. Hepatic water gives 

 to thefe fyrups a dark brown colour. This is fufficient to 

 convince us that either lead or copper is prefent. 



Let us now confider feparateiy each of the principles of 

 our lemon juice in regard to fermentation. 



Strictly fpeaking, none of them is capable feparateiy of 

 palling to fpiritous fermentation, and not even to the acetous. 



H 3 The. 



