Preparation of the Citric Acid. 11$ 



In 4 ounces or 32 drams of chalk, then, we have the fol- 

 lowing quantities, a few fractions excepted : 

 Argil 1 



Water I 



Carbonic acid * I2f- 



Lime - - 17^ 



Total 3 % 



It is now evident that the earthy bafe furniflied to 6o\ of 

 citrate by 32 drams of chalk, was 17J drams of lime, or i8~ 

 including the argil. 



It is alfo evident that the citric acid, which affumed the 

 place of the 12J drams of carbonic acid, amounted to 41 ~ 

 drams. If to thefe 58^ drams of pure citrate, i drams of 

 water and argil be added, we (hall have for the whole product 

 60 \ drams. 



From thefe proportions it will be found by calculation 

 that it muft contain about 30 J of lime, mixed with a Tittle 

 argil, in a quintal of citrate; but, having calcined a hundred 

 parts of this citrate, it left §i\ of lime, a proportion very near 

 to the former; and if we deduct from this lime about ii of 

 argil, we fhall have in the quintal of citrate, 

 Lime - - 30 1 

 Citric acid - 7° J 



But the real quantity of acid will be lefs by all the water with 

 Which it may be united in the citrate. This, however, I did 

 not examine. 



The citrate of Chalk, as Scheele has remarked, is very 

 little foluble in water, and the fdlution has no ftriking favour* 

 It is not rendered turbid by fpirit of wine, and it produces 

 no change either on turnfole paper or on the folution of ful- 

 phate of potafh. The fluoric, phofphoric, and boracic acids 

 make no impreffion upon it ; but the oxalate of potafh and 

 the oxalic acid precipitate from it the lime. 



The extractive ley Contains, befides mucilage and extract, 

 malate of lime, which fpirit of wine immediately precipitates 

 from it, if it has been concentrated by evaporation. Extract 

 of this ley has the colour, fmell, and favour, common to the 

 extracts of plants. If it has been concentrated only to the 

 confidence of fyrup, it fpeedily becomes covered with mouldi- 

 rtefs. 



The colour of lemon juice is not changed by a few drops of 

 the nitrate of iron, becaufe excefs of the acids rediflblves the 

 gallate, or combination of iron with the aftringent principle ; 

 but if this excefs be taken away by potafh, the vinous colour, ' 



H % but 



