CHEMISTRY. 



.59 



"Elements colour. When cooled, it concretes into a hard mass, 

 but the nature of the acid is changed. It has now 

 ;rv ' acquired the property of deliquescing when exposed 

 to the air. When distilled, this acid yields an acid 

 liquid formerly called pyrotartarous acid, but now 

 known to be the acetic disguised by means of an em- 

 pyreumatic oil. When combined with a base and 

 distilled, tartaric acid is decomposed, and converted 

 into maler, carbonic acid, heavy inflammable air, and 

 charcoal. 



It dissolves readily in water, and when the solution 

 is diluted, the acid undergoes spontaneous decompo- 

 sition. 



None of the simple substances produce any striking 

 effect upon this acid. It combines with the salifiable 

 bases, and forms a class of salts called tartrates. 

 (fomposi- According to Thenard and Gay-Lussac, it is com- 



* posed of Oxygen, 69.321 



Carbon, 24.050 

 Hydrogen, 6.629 



100 



SECT. X. Of Citric Acid. 



Citric acid. This acid existi in the juice of oranges and lemons, 

 and was first obtained pure by Scheele. Hit process 

 was this : 



TIow ob- Saturate lemon-juice with chalk. A precipitate 



*" Ied - falls. Wash this precipitate, and pour on it as much 

 sulphuric acid as will saturate the chalk employed, 

 previously diluted with six times its weight of water. 

 Digest, filter, and evaporate the liquid. The citric 

 acid crystallize*. 



Its proper- This acid crystallize* in rhomboidal prisms. The 

 crystals are not altered by exposure to the air. The 

 taste is acid, and vegetable blues are reddened by it. 

 It dissolves in less than its weight of water. 



It is not acted on by the simple substances. It 

 oxidizes a few of the metals. It combines with the 

 salifiable bases, and forms a class of salts called ci- 

 tralct. 



Sulphuric acid decomposes it. Nitric acid converts 

 it into oxalic acid, or into acetic acid, if used in excess. 

 Composi- Its constituents, according to Thenard and Gay- 

 llou - Lussac, are a* follows : 



Oxygen, 59-859 

 Cirbon, 33.81 1 

 Hydrogen, 6.330 



100 



SECT. XI. QfKinic Acid. 



Kinic aciJ. This acid was discovered by Vauquelin, in a salt 

 first obtained from Jesuits bark, by Deschamps. This 

 salt is a compound of kinic acid and lime. 



How ob- Vauqui-liii dlMotVed the salt in water, and precipi- 



tained. tated the lime by means of oxalic acid. The liquid 

 was evaporated to the consistence of a syrup, and then 

 set aide. No crystals formed in it at first, but on 

 being touched, it wholly crystallized in diverging 

 plates. 



In proper- Its colour is somewhat brown, its taste very acid 



Element 9 



of 

 Chemistrv. 



and bitter. It was not altered by exposure to the 

 air. It is very soluble in water. It does not preci- 

 pitate silver nor lead from their solutions. When 

 heated, it is decomposed, and charcoal remains behind. 



SECT. XII. OfSacIac/ic Acid. 



This acid was discovered by Sc-heele, who formed f*y ae 

 it by digesting sugar of milk in nitric acid. Fourcroy 

 and Vauquelin ascertained, afterwards, that it is form- How ^' 

 ed when gum is heated with nitric acid and the so- a 

 lution allowed to cool. A white powder precipitates, 

 which is the acid in question. 



Saclactic acid, thus obtained, is in the form of a Its proper- 

 white gritty powder, with a slight acid taste. It is l ' ei> 

 only slightly soluble in boiling water. The solution 

 has an acid taste, and reddens vegetable blues. 



The compounds which this acid forms with the 

 salifiable bases, are called saccolates. 



The constituents, according to Thenard and Gay- Composl- 

 Lussac, are as follows : ' 1<>n * 



Oxygen, 62.69 

 Carbon, 33.09 

 Hydrogen, 3.62 



100 



SECT. XIII. Of Uric Add. 



This acid was discovered by Scheele in urinary Uric aci ^' 

 calculi, and first called lit/tic acid. But this term 

 was afterwards laid aside, and uric acid substituted ; 

 because this acid constitutes one of the ingredients 

 of urine. For the best account of the properties of 

 this acid, we are indebted to Dr Henry. 



It is obtained by dissolving the calculi, composed How ob- 

 chiefly of it, in alkaline ley, and precipitating by talned 

 means of muriatic or acetic acids. The wlu'te pow- 

 der which falls, when well edulcorated, is pure uric 

 acid. 



It is a white powder, without taste or smell. It It pfopfcr. 

 reddens vegetable blues, and requires more than 1700 *'" 

 parts of cold water to dissolve it. 



It dissolves readily in fixed alkaline solutions, but 

 not in alkaline carbonates. It dissolves in nitric 

 acid ; and when the solution is evaporated nearly to 

 dryness, it assumes a fine pink colour, which becomes 

 much deeper when water is added, so as to have a 

 near resemblance to carmine. The watery solution 

 of this matter loses its red colour in a few hours, and 

 it cannot afterwards be restored. 



Oxymunatic acid readily converts the uric into the 

 oxalic acid. 



When distilled, carbonate of ammonia is obtained, 

 and a saline sublimate, which Dr Henry has shown 

 to be a compound of ammonia with a peculiar acid. 



SECT. XIV. Of Malic Acid. 



This acid was discovered by Scheele. It exists in Malic aci3. 

 apples, and in a variety of vegetable substances. It 

 is formed also by the action of nitric acid on sugar. 



Scheele obtained it by saturating the juice of apples H ? w oB * 

 with potash, precipitating by acetite of lead, digest- taiued 



