86 Detection of Adulterations. 



For the purpose of detecting these additions, boil the salt in twen- 

 ty times its weight of water, adding pure ammonia to neutralize 

 the excess of acid. If any portion remain undissolved, it may be 



nn 



•Tartar emetic sometimes 



hydrochloric acid, it is carbonate of lime. 



Tartrate of Potash and Antimony* 

 contains an admixture of cream of tartar. To ascertain the pres- 

 ence of this salt, dissolve one part of the tartrate in four of water, 

 and observe whether or not it precipitates a solution of the hydro- 

 chlorate of barytes, the oxalate of ammonia, or the acidulated solu- 

 tion of the bi-acetate of lead. The last, which is a very delicate 

 test, is prepared by dissolving eight parts of crystallized bi-acetale in 

 thirty two parts of hot water, filtering the solution, and adding fifteen 

 parts of acetic acid sp. gr. 1.064. The precipitate does not always 

 occur immediately. Tartar emetic prepared from glass of antimony 

 is apt to contain tartrate of iron ; the presence of which is to be dis- 

 covered by the usual tests of iron. The crystallized tartar is the 

 purest. 



Vinegar. — The strength of this acid varies ; but when of the 

 average strength, one hundred parts dissolve eight parts of carbon- 

 ate of lime. Various acrid substances are sometimes put into weak 

 vinegar, to give intensity to its taste ; but it is observed that when 

 such vinegar is neutralized by carbonate of potash, it still retains its 

 taste ; which is not the case when the vinegar is pure. 



To detect the presence of sulphuric acid, which is one of the 

 worst adulterations, evaporate the vinegar to one eighth its original 

 volume, and observe whether its acidity be not increased. Add to 

 the concentrated liquid five times its volume of alcohol sp. gr. .837, 

 filter, add an equal volume of water, evaporate until most of the al- 

 cohol is removed, and add a very dilute solution of nitrate of bary- 

 tes. This, if sulphuric acid be present, will afford a precipitate in- 

 soluble in nitric acid. 



To determine the presence of hydrochloric acid, distil a portion 

 of the vinegar, and add to the distilled liquid nitrate of silver ; which 

 gives, with hydrochloric acid, a precipitate insoluble in nitric acid, 

 but soluble in ammonia. The nitric acid is detected by neutrali- 



* 1 • 



the vinegar with carbonate of potash, crystallizing, and applying 



- i i • * • . _ _ . « 





potash 



When vinegar contains oxalic or tartaric acid, it yields these sub- 

 stances in crystals when evaporated, and their characters will corre- 

 spond with those detailed in the popular books on chemistry. 



