442 On the Nature and Comb mat ions 



powder, but if obtained from solution in its own acid, it is irt 

 beautiful silvery crystals. Neither of these salts is soluble in 

 500U times its weight of water. The sorbate when heated to 

 redness undergoes a somewhat brilliant combustion. 



The supcr-sorbate never assumes the solid form ; its taste is 

 sweet. Thus the sorbic acid forms three combinations with 

 lead: malic forms but two; the neutral malatc, which is an tm- 

 crystallizal)le soft powder, and the super-malate. Not less di- 

 stinguishable are the two acids by their combinations with the 

 alkalies. 



Sorbate of potash, when there is an exoes? of acid, forms per- 

 manent crystals solul)le in water, but insoluble in alcohol. 



Sorbate of soda, when there is an excess of acid, forms per- 

 manent crystals, which agree in characters with the former. 



Sorbate' of ammonia, when there is an excess of acid, also 

 forms permanent crystals of similar characters with the ])re- 

 ceding. 



These three salts will not crystallize unless there be a tolera- 

 ble excess of acid ; they are to be considered as super- salt?. 

 That of soda even reciu'ires the aid of cold to render it solid. 

 The malates of potash, soda, and ammonia are known to be un- 

 crystallizable and deliquescent. 



In the combinations of these acids with earths, there are also 

 striking differences. Scheele found, tbat when he added car- 

 bonate of lime to malic acid, a great quantity was dissolved, but 

 the solution gave with litmus indications of an abundant acid 

 »,vhich it was inipossible to neutralize with further additions of 

 chalk*. 1 obtained the same result Avith malic acid from the 

 Sempervivnni; I even found that the solution might be boiled to 

 dryness, on a fresh portion of carbonate of lime ; yet when lixi- 

 viated, the filtered solution would still redden litmus, and the 

 salt finally afforded was readily solul)le. These results often ob- 

 tained, prove that it is not possible to form neutral malate from 

 carbonate of lime. 



But with sorbic acid the case was quite different. When it 

 was diluted, and agitated for a little while with carbonate of 

 lime, the solution, before it could be filtered, deposited the 

 principal part of the sorbate in the form of a discrete, gritty 

 powder. The liquor when filtered produced no redness in tinc- 

 ture of litmus, and every thing proved that the fluid by mere 

 agitation over the carbonate had been completely neutralized. 



The same results which Scheele obtained from lime were af- 

 forded by carbonate of barytes: but with sorbic acid I produced 

 9. liquor which showed no" signs of acidity. The best test for 



• Sclieele, Chun. Annul. 1785, ii, 292. 



ascertaining 



