C H E M I S T R Y. 



85 



Elements traded from sorrel, and usually sold under the name 



* of the essential salt of lemons. Its crystals are 



2" small opak.' parallelepipeds. It has an acid, pun- 



'"" gent, bitterish taste. It dissolves ic about ten times 



its weight of boiling water, but requires a much 



greater quantity of cold water. It is not altered by 



exposure to the air. It contains exactly double the 



quantity of acid which the oxalate of potash contains. 



Sp. 3. Qiiadroxalate of Potash. This salt was 

 lately discovered by Dr Wollaston, by digesting su- 

 peroxalate of potash in nitric or muriatic acids. One 

 half of the alkali is separated, and there remains be- 

 hind a salt, which may be obtained in crystals, and 

 which contains four times the proportion of acid that 

 exists in oxalate of potash. 



Sp. 4. Ozalate of Soda. This salt crystallizes, 

 and has nearly the same tasts with the oxalate of 

 potash. When heated it falls to powder, being de- 

 prived of its water of crystaUixation. 



Sp. 5. Oxalate of Ammonia. This salt crystal- 

 lizes in four sided prisms, terminated by dihedral 

 summits. Its taste is bitter and unpleasant, some- 

 what similar to that of sal-ammoniac. ICO parts of 

 cold water dissolve 4A of this salt. It is insoluble in 

 alcohol. When distilled, carbonate of ammonia is 

 disengaged, a little acid sublimed, and some charcoal 

 left behind. 



Sp. 6. Oxalate of Alumina. This salt does not 

 crystallise, and has a yellow colour. It has a sweet 

 astringent taste, is soluble in water, and sparingly 

 soluble in alcohol. It deliquesces in the air. 



The remaining species are nearly insoluble in water. 



Sp. 7. Oxalate of Magnesia. This is a tasteless 

 white powder, not sensibly soluble in water ; yet ox- 

 alate of ammonia does not occasion a precipitate when 

 dropt into sulphate of magnesia. 



Sp. 8. Oxalate of Lime. This ii a white powder, 

 insoluble in water, which makes its appearance when 

 oxalate of ammonia is poured into any neutral salt 

 with base of line. It is tasteless, and dissolve* readi- 

 ly in acids. 



Sp. 9. Oxalate of Barytes. This is an insoluble, 

 tasteless, white powder. With an excess of acid, it 

 may be obtained crystallized in needles. 



Sp. 10. Oxalate of Slrontian. This is a white, in- 

 soluble, tasteless powder. 



Sp. 11. OxaJate of Yttria. This is also a white, 

 insoluble, tasteless powder. 



The following Table exhibits the composition of 

 the oxalaU-5, at far as ascertained : 



GESUS VI I. Mellates. 



Elements 



of 

 Chemistry. 



This genus of salts has been but imperfectly exa- Mella'tcT" 

 mined. The alkaline mellates are soluble in water, 

 and crystallize. The earthy do not appear soluble, 

 and therefore are usually in the state of flaky pow- 

 ders. 



GENUS VIII. Tartratet. 



These salts, when exposed to a red heat, are de- Tartrates. 

 composed, and the base remains in the state of a car- 

 bonate, usually mixed with charcoal. The earthy 

 tartratcs arc nearly insoluble in water ; the alkaline 

 are soluble ; but they combine with an excess of 

 acid, and are converted into supertartratesi which are 

 much less soluble than the tartrates. They readily 

 combine with another base, and form triple oults. 



Sp. 1. liartrate of Potash. Of this salt there are 

 two varieties. The first, containing an excess of 

 acid, is usually called tartar. The second, which is 

 neutral, is called tartrale of potash, and formerly it 

 was called soluble tartar, from its greater solubility 

 in water. 



Variety 1. Sitperlartrate of Potash, or Tartar. .. 

 This salt deposites itself on the sides of casks in which 

 wine is kept. It is purified by solution and evapora- 

 tions. It is from it that tartaric acid is usually ob- 

 tained. Its crystals are small and irregular. Its 

 taste is acid, and rather unpleasant. It is brittle, 

 and soluble in about GO. parts of cold water. It it 

 not altered by exposure to the air, but when kept 

 dissolved in water is gradually decomposed. When 

 distilled, it gives out a great deal of heavy inflamma- 

 ble air, and carbonic acid gas ; and an acid liquor is 

 obtained, formerly called pyrotarlarous ac/, but now 

 known to be merely the acetic, contaminated with a 

 little empyreumatic oiL The tartar of commerce 

 contains about 5 per cent, of tartrate of lime. 



Variety 2. Tarlrate of Potash. This salt may be 

 formed by saturating the preceding with potash or 

 its carbonate. Its crystals are flat four-sided rectan- 

 gular prisms, terminated by dihedral summits. It 

 dissolves in about its own weight of cold water. Itt 

 taste is an unpleasant bitter. 



Sp. 2. Tartrate of Soda. This salt crystallizes in 

 needles. It is soluble in its own weight of cold 

 water. It is capable of forming a supertartrate. 



Sp. 3. Tartrate of Ammonia. This salt crystal- 

 lizes in small p >lygonal prisms. It has a cooling 

 bitter taste. It is very soluble in water. It is said 

 also to be capable of lorming a supertartrate. 



Sp. 4. Tartrate of Potash and Soda. This salt 

 may be formed by saturating tartar with carbonate 

 of ?od.'. It was formerly called Rochelle salt, and 

 salt ofSeignelte. It crystallizes in large irregular 

 prisms. It has a bitter taste, is very soluble in wa- 

 ter, and effli/ivhces when exposed to the air. 



Tarta. forms also a triple salt when neutralized by 

 ammonia. 



Sp. 5. Tartrate of Magnesia. Tliis salt is inso- 

 luble in water, unit-Is it contains an excess of acid. 

 In that case it crystallites in six-sided prisms. 



Tartar forms a triple salt when neutralized by 

 magnesia. 



