106 On Citric Acid. 



an equal quantity vvas taken of that which contained vinegar 

 mixed with it, and both these parcels were accurately saturated 

 with carbonate of lime*, and left 24 hours undisturbed until the 

 citrate of lime thus composed should be deposited. 



On pouring off the supernatant liquors from the two parcels 

 of calcareous citrate, and drying both their precipitates equally, 

 the following results presented themselves. The citrate of lime 

 from the pine juice, when perfectly dried, vveighed 13S grain-, 

 while that from t!ie adulterated parcel weighed only 129 grains. 

 The specific gravity of the supernatant liquor from the former 

 was 1"007G, or 16 ounces and 2 drachms to the wine pint; but 

 that from the latter, in consecjuenee of the lime taken up by the 

 vinegar, was r()135, or IG ounces and 3 drachms and a half to 

 the pint. Bv a similar experiment, the adulteration of lemon- 

 juice with vinegar may at any time inevitably be detected. 



When it has thus been found that the lemon-juice contains no 

 admixture of other acids, the next step ought to be to ascertain 

 how much real citric acid any given quantity of it actually holds 

 in solution. For though it may not have been designedly sophis- 

 ticated by any extraneous matters, it may be very inferior from 

 other causes, the extent of which caa only be accurately disco- 

 vered by the application of another chemical test. 



For instance, the fruit of which it was made may have been 

 gathered in an unfavourable month, after the descent of the 

 heavy rains; or deteriorated by the spontaneous decomposition 

 which is occasioned by age ; or it mav have been diluted with 

 water ; all of which mav be apprehended, when it is not known 

 how many hands the juice has passed through before it comes 

 into the possession of the consumer. 



The mode which naturally suggests itself of ascertaining this 

 point, is by means of an alkali ; for, if it be proved by the fore- 

 going tests that the juice contains no admixture of other acids, 

 the amount of the crystals of citric acid which it will yield will 

 be in exact proportion to the quantity of alkali which it requires 

 for its saturation. 



To adapt this theory to practice, all that is necessary is to se- 

 lect some alkali, such as pearl ash, or the crystals of soda, of 

 which a solution is to be made, something below the point of 

 saturation ; and when this has been filtrated through blotting 

 paper, and its specific gravity noted down, it will be ready for 

 use, and should be carefully laid by, to have recourse to when- 

 ever occasion requires. 



It will be necessary also to procure some of the test-paper 



• The 1200 grains of pure K-mon-juice required 98 grains of carbonate of 

 lime, whereas the same weight of acid previously sophisticated with vinegar took 

 102 grains for its complete saturation. 



which 



