TARTARIC ACID. 285 



The Venetian cream of tartar, however, bears a 

 higher price than the French in the market, the 

 former being about ,3. 16s., and the other 3. 13s. 

 per cwt. It is admitted at a duty of 4s. Sd. per cvvt. 



The average annual import for the five preceding 

 years was 882 casks ; each cask weighing 11 cwt. 



Tartar, both in its crude and its prepared state, 

 was long used in the arts before its component parts 

 were separated and analyzed by chemists. It was 

 then discovered to be a peculiar acid, combined 

 with potash, in a greater proportion, however, than 

 to form a neutral salt ; hence the term acidulous 

 tartrate of potash. The supposition that it was 

 formed during the fermentation of the wine, was 

 disproved by Boerhaave, Newmann, and others, who 

 showed that it existed ready-formed in the juice of 

 the grape. This peculiar acid, distinguished as tar- 

 taric acid, has been likewise found in other fruits, 

 particularly before they are very ripe. It is contained 

 in the tamarind, and also in sumac, balm, carduus- 

 benedictus, and the roots of rest-harrow, germander, 

 and sage. 



The method of separating the tartaric acid from the 

 cream of tartar was among the earliest discoveries of 

 Scheele. He saturated the superfluous acid by adding 

 chalk or carbonate of lime to a solution of this acidu- 

 lous salt in boiling water till effervescence ceased ; or till 

 the carbonate of lime, which is a combination of lirne 

 and carbonic acid gas, had been wholly decomposed, 

 the lime uniting with the tartaric acid and the carbonic 

 acid gas now disengaged, escaping. The acid held 

 in combination with the lime, was thus obtained under 

 the form of tartrate of lime ; this was again made to 

 part with its acid by means of the sulphuric, to which 

 the lime having a greater affinity combined, leaving 

 the tartaric acid free. Thenard recommends another 



