VIII. ACIDS.— OxALiA. 299 



strain and evaporate by a water bath, that it may crystallize : the 

 mother water yields by evaporation and crystallization tartrate of 

 potash. Tartaric acid is used as a substitute for lemon juice and 

 citric acid. 



Spirit of tartar, Spirihis tartari. Distil argol and separate 

 the acid spirit from the oil by a funnel : the residuum yields, by 

 burning in the open air, very pure subcarb. of potash. It may 

 be used for distilled vinegar. 



Lactic acid. This may be extracted both from milk and 

 from the juice of beet root. If from the latter it should be left 

 in a stove of a fixed temperature, between 25° and 30°. After a 

 few days, fermentation takes place, and hydrogen mixed with 

 carburctted hydrogen is abundantly evolved. The fermentation 

 ended, and the liquid restored to its former fluidity — which gene- 

 rally occupies two months — it is evaporated to a syrupy consis- 

 tence: crystals of mannete then appear, and with them a sugar. 

 The product of the evaporation is treated with alcohol, which 

 dissolves the lactic acid, leaving a quantity of precipitate. The 

 alcoholic extract is taken up by the water, wherefrom a fresh 

 deposit is made; the fluid is then saturated with carbonate of 

 zinc, and a copious precipitation again takes place. The lactate 

 of zinc, when concentrated, cr^'stallizes, is collected and heated 

 with water, to which some animal charcoal previously washed 

 ith iiydrochloric acid is added ; the whole is then Altered, and 

 le lactate of zinc, perfectly white, crystallizes : these crystals are 

 ^ain washed with boiling alcohol, in which they are insoluble. 

 \y successive treatment with baryta and sulphuric acid the lactic 

 ;id is separated and concentrated in vacuo. Finally, on shaking 

 with sulphuric a?ther which dissolves it, a flaky matter is sepa- 

 ited — when concentrated in vacuo, lactic acid is a colourless 

 luid of a syrupy consistence ; it is inodorous, and intensely acid 

 to the taste — very soluble in water and alcohol, rapidly dissolves 

 phosphate of lime. Has been found of use in dyspepsia or mere 

 debility of the digestive organs, may be given in the form of 

 lemonade or lozenges. 



Oxalic Acin, Acid nf siu/ar, Acidum oxalicum. Starch 25 oz., 

 put it into a retort, add first common nitric acid 75 oz., and when 

 the action is over add nitric acid 24 oz. ; heat, decant, leave it to 

 crystallize, decant the mother water. Add fresh nitric acid to the 

 mother water, and crystallize again 3 or 4 times until 200 oz. or 

 more nitric acid has been used. Produces about 12{ oz. of crystal- 

 lized oxalic acid ; the crystals are purified by solution in water and 



crystallization. From its resemblance to Kpsoni salts it has 

 occasioned several accidents, but it has a strong acid taste. Used 

 for cleaning l)oot-top8, and as a precipitant for lime, either free 

 or in combination. The nitrous gas which is disengaged is used 



